Feeds:
Posts
Comments

Archive for the ‘MicroEngineering Cell-Tissue & Systems’ Category


Use of 3D Bioprinting for Development of Toxicity Prediction Models

Curator: Stephen J. Williams, PhD

SOT FDA Colloquium on 3D Bioprinted Tissue Models: Tuesday, April 9, 2019

The Society of Toxicology (SOT) and the U.S. Food and Drug Administration (FDA) will hold a workshop on “Alternative Methods for Predictive Safety Testing: 3D Bioprinted Tissue Models” on Tuesday, April 9, at the FDA Center for Food Safety and Applied Nutrition in College Park, Maryland. This workshop is the latest in the series, “SOT FDA Colloquia on Emerging Toxicological Science: Challenges in Food and Ingredient Safety.”

Human 3D bioprinted tissues represent a valuable in vitro approach for chemical, personal care product, cosmetic, and preclinical toxicity/safety testing. Bioprinting of skin, liver, and kidney is already appearing in toxicity testing applications for chemical exposures and disease modeling. The use of 3D bioprinted tissues and organs may provide future alternative approaches for testing that may more closely resemble and simulate intact human tissues to more accurately predict human responses to chemical and drug exposures.

A synopsis of the schedule and related works from the speakers is given below:

 

8:40 AM–9:20 AM Overview and Challenges of Bioprinting
Sharon Presnell, Amnion Foundation, Winston-Salem, NC
9:20 AM–10:00 AM Putting 3D Bioprinting to the Use of Tissue Model Fabrication
Y. Shrike Zhang, Brigham and Women’s Hospital, Harvard Medical School and Harvard-MIT Division of Health Sciences and Technology, Boston, MA
10:00 AM–10:20 AM Break
10:20 AM–11:00 AM Uses of Bioprinted Liver Tissue in Drug Development
Jean-Louis Klein, GlaxoSmithKline, Collegeville, PA
11:00 AM–11:40 AM Biofabrication of 3D Tissue Models for Disease Modeling and Chemical Screening
Marc Ferrer, National Center for Advancing Translational Sciences, NIH, Rockville, MD

Sharon Presnell, Ph.D. President, Amnion Foundation

Dr. Sharon Presnell was most recently the Chief Scientific Officer at Organovo, Inc., and the President of their wholly-owned subsidiary, Samsara Sciences. She received a Ph.D. in Cell & Molecular Pathology from the Medical College of Virginia and completed her undergraduate degree in biology at NC State. In addition to her most recent roles, Presnell has served as the director of cell biology R&D at Becton Dickinson’s corporate research center in RTP, and as the SVP of R&D at Tengion. Her roles have always involved the commercial and clinical translation of basic research and early development in the cell biology space. She serves on the board of the Coulter Foundation at the University of Virginia and is a member of the College of Life Sciences Foundation Board at NC State. In January 2019, Dr. Presnell will begin a new role as President of the Amnion Foundation, a non-profit organization in Winston-Salem.

A few of her relevant publications:

Bioprinted liver provides early insight into the role of Kupffer cells in TGF-β1 and methotrexate-induced fibrogenesis

Integrating Kupffer cells into a 3D bioprinted model of human liver recapitulates fibrotic responses of certain toxicants in a time and context dependent manner.  This work establishes that the presence of Kupffer cells or macrophages are important mediators in fibrotic responses to certain hepatotoxins and both should be incorporated into bioprinted human liver models for toxicology testing.

Bioprinted 3D Primary Liver Tissues Allow Assessment of Organ-Level Response to Clinical Drug Induced Toxicity In Vitro

Abstract: Modeling clinically relevant tissue responses using cell models poses a significant challenge for drug development, in particular for drug induced liver injury (DILI). This is mainly because existing liver models lack longevity and tissue-level complexity which limits their utility in predictive toxicology. In this study, we established and characterized novel bioprinted human liver tissue mimetics comprised of patient-derived hepatocytes and non-parenchymal cells in a defined architecture. Scaffold-free assembly of different cell types in an in vivo-relevant architecture allowed for histologic analysis that revealed distinct intercellular hepatocyte junctions, CD31+ endothelial networks, and desmin positive, smooth muscle actin negative quiescent stellates. Unlike what was seen in 2D hepatocyte cultures, the tissues maintained levels of ATP, Albumin as well as expression and drug-induced enzyme activity of Cytochrome P450s over 4 weeks in culture. To assess the ability of the 3D liver cultures to model tissue-level DILI, dose responses of Trovafloxacin, a drug whose hepatotoxic potential could not be assessed by standard pre-clinical models, were compared to the structurally related non-toxic drug Levofloxacin. Trovafloxacin induced significant, dose-dependent toxicity at clinically relevant doses (≤ 4uM). Interestingly, Trovafloxacin toxicity was observed without lipopolysaccharide stimulation and in the absence of resident macrophages in contrast to earlier reports. Together, these results demonstrate that 3D bioprinted liver tissues can both effectively model DILI and distinguish between highly related compounds with differential profile. Thus, the combination of patient-derived primary cells with bioprinting technology here for the first time demonstrates superior performance in terms of mimicking human drug response in a known target organ at the tissue level.

A great interview with Dr. Presnell and the 3D Models 2017 Symposium is located here:

Please click here for Web based and PDF version of interview

Some highlights of the interview include

  • Exciting advances in field showing we can model complex tissue-level disease-state phenotypes that develop in response to chronic long term injury or exposure
  • Sees the field developing a means to converge both the biology and physiology of tissues, namely modeling the connectivity between tissues such as fluid flow
  • Future work will need to be dedicated to develop comprehensive analytics for 3D tissue analysis. As she states “we are very conditioned to get information in a simple way from biochemical readouts in two dimension, monocellular systems”  however how we address the complexity of various cellular responses in a 3D multicellular environment will be pertinent.
  • Additional challenges include the scalability of such systems and making such system accessible in a larger way
  1. Shrike Zhang, Brigham and Women’s Hospital, Harvard Medical School and Harvard-MIT Division of Health Sciences and Technology

Dr. Zhang currently holds an Assistant Professor position at Harvard Medical School and is an Associate Bioengineer at Brigham and Women’s Hospital. His research interests include organ-on-a-chip, 3D bioprinting, biomaterials, regenerative engineering, biomedical imaging, biosensing, nanomedicine, and developmental biology. His scientific contributions have been recognized by >40 international, national, and regional awards. He has been invited to deliver >70 lectures worldwide, and has served as reviewer for >400 manuscripts for >30 journals. He is serving as Editor-in-Chief for Microphysiological Systems, and Associate Editor for Bio-Design and Manufacturing. He is also on Editorial Board of BioprintingHeliyonBMC Materials, and Essays in Biochemistry, and on Advisory Panel of Nanotechnology.

Some relevant references from Dr. Zhang

Multi-tissue interactions in an integrated three-tissue organ-on-a-chip platform.

Skardal A, Murphy SV, Devarasetty M, Mead I, Kang HW, Seol YJ, Shrike Zhang Y, Shin SR, Zhao L, Aleman J, Hall AR, Shupe TD, Kleensang A, Dokmeci MR, Jin Lee S, Jackson JD, Yoo JJ, Hartung T, Khademhosseini A, Soker S, Bishop CE, Atala A.

Sci Rep. 2017 Aug 18;7(1):8837. doi: 10.1038/s41598-017-08879-x.

 

Reconstruction of Large-scale Defects with a Novel Hybrid Scaffold Made from Poly(L-lactic acid)/Nanohydroxyapatite/Alendronate-loaded Chitosan Microsphere: in vitro and in vivo Studies.

Wu H, Lei P, Liu G, Shrike Zhang Y, Yang J, Zhang L, Xie J, Niu W, Liu H, Ruan J, Hu Y, Zhang C.

Sci Rep. 2017 Mar 23;7(1):359. doi: 10.1038/s41598-017-00506-z.

 

 

A liver-on-a-chip platform with bioprinted hepatic spheroids.

Bhise NS, Manoharan V, Massa S, Tamayol A, Ghaderi M, Miscuglio M, Lang Q, Shrike Zhang Y, Shin SR, Calzone G, Annabi N, Shupe TD, Bishop CE, Atala A, Dokmeci MR, Khademhosseini A.

Biofabrication. 2016 Jan 12;8(1):014101. doi: 10.1088/1758-5090/8/1/014101.

 

Marc Ferrer, National Center for Advancing Translational Sciences, NIH

Marc Ferrer is a team leader in the NCATS Chemical Genomics Center, which was part of the National Human Genome Research Institute when Ferrer began working there in 2010. He has extensive experience in drug discovery, both in the pharmaceutical industry and academic research. Before joining NIH, he was director of assay development and screening at Merck Research Laboratories. For 10 years at Merck, Ferrer led the development of assays for high-throughput screening of small molecules and small interfering RNA (siRNA) to support programs for lead and target identification across all disease areas.

At NCATS, Ferrer leads the implementation of probe development programs, discovery of drug combinations and development of innovative assay paradigms for more effective drug discovery. He advises collaborators on strategies for discovering small molecule therapeutics, including assays for screening and lead identification and optimization. Ferrer has experience implementing high-throughput screens for a broad range of disease areas with a wide array of assay technologies. He has led and managed highly productive teams by setting clear research strategies and goals and by establishing effective collaborations between scientists from diverse disciplines within industry, academia and technology providers.

Ferrer has a Ph.D. in biological chemistry from the University of Minnesota, Twin Cities, and completed postdoctoral training at Harvard University’s Department of Molecular and Cellular Biology. He received a B.Sc. degree in organic chemistry from the University of Barcelona in Spain.

 

Some relevant references for Dr. Ferrer

Fully 3D Bioprinted Skin Equivalent Constructs with Validated Morphology and Barrier Function.

Derr K, Zou J, Luo K, Song MJ, Sittampalam GS, Zhou C, Michael S, Ferrer M, Derr P.

Tissue Eng Part C Methods. 2019 Apr 22. doi: 10.1089/ten.TEC.2018.0318. [Epub ahead of print]

 

Determination of the Elasticity Modulus of 3D-Printed Octet-Truss Structures for Use in Porous Prosthesis Implants.

Bagheri A, Buj-Corral I, Ferrer M, Pastor MM, Roure F.

Materials (Basel). 2018 Nov 29;11(12). pii: E2420. doi: 10.3390/ma11122420.

 

Mutation Profiles in Glioblastoma 3D Oncospheres Modulate Drug Efficacy.

Wilson KM, Mathews-Griner LA, Williamson T, Guha R, Chen L, Shinn P, McKnight C, Michael S, Klumpp-Thomas C, Binder ZA, Ferrer M, Gallia GL, Thomas CJ, Riggins GJ.

SLAS Technol. 2019 Feb;24(1):28-40. doi: 10.1177/2472630318803749. Epub 2018 Oct 5.

 

A high-throughput imaging and nuclear segmentation analysis protocol for cleared 3D culture models.

Boutin ME, Voss TC, Titus SA, Cruz-Gutierrez K, Michael S, Ferrer M.

Sci Rep. 2018 Jul 24;8(1):11135. doi: 10.1038/s41598-018-29169-0.

A High-Throughput Screening Model of the Tumor Microenvironment for Ovarian Cancer Cell Growth.

Lal-Nag M, McGee L, Guha R, Lengyel E, Kenny HA, Ferrer M.

SLAS Discov. 2017 Jun;22(5):494-506. doi: 10.1177/2472555216687082. Epub 2017 Jan 31.

 

Exploring Drug Dosing Regimens In Vitro Using Real-Time 3D Spheroid Tumor Growth Assays.

Lal-Nag M, McGee L, Titus SA, Brimacombe K, Michael S, Sittampalam G, Ferrer M.

SLAS Discov. 2017 Jun;22(5):537-546. doi: 10.1177/2472555217698818. Epub 2017 Mar 15.

 

RNAi High-Throughput Screening of Single- and Multi-Cell-Type Tumor Spheroids: A Comprehensive Analysis in Two and Three Dimensions.

Fu J, Fernandez D, Ferrer M, Titus SA, Buehler E, Lal-Nag MA.

SLAS Discov. 2017 Jun;22(5):525-536. doi: 10.1177/2472555217696796. Epub 2017 Mar 9.

 

Other Articles on 3D Bioprinting on this Open Access Journal include:

Global Technology Conferences on 3D BioPrinting 2015 – 2016

3D Medical BioPrinting Technology Reporting by Irina Robu, PhD – a forthcoming Article in “Medical 3D BioPrinting – The Revolution in Medicine, Technologies for Patient-centered Medicine: From R&D in Biologics to New Medical Devices”

Bio-Inks and 3D BioPrinting

New Scaffold-Free 3D Bioprinting Method Available to Researchers

Gene Editing for Gene Therapies with 3D BioPrinting

 

Read Full Post »

Immunoediting can be a constant defense in the cancer landscape


Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

There are many considerations in the cancer immunoediting landscape of defense and regulation in the cancer hallmark biology. The cancer hallmark biology in concert with key controls of the HLA compatibility affinity mechanisms are pivotal in architecting a unique patient-centric therapeutic application. Selection of random immune products including neoantigens, antigens, antibodies and other vital immune elements creates a high level of uncertainty and risk of undesirable immune reactions. Immunoediting is a constant process. The human innate and adaptive forces can either trigger favorable or unfavorable immunoediting features. Cancer is a multi-disease entity. There are multi-factorial initiators in a certain disease process. Namely, environmental exposures, viral and / or microbiome exposure disequilibrium, direct harm to DNA, poor immune adaptability, inherent risk and an individual’s own vibration rhythm in life.

 

When a human single cell is crippled (Deranged DNA) with mixed up molecular behavior that is the initiator of the problem. A once normal cell now transitioned into full threatening molecular time bomb. In the modeling and creation of a tumor it all begins with the singular molecular crisis and crippling of a normal human cell. At this point it is either chop suey (mixed bit responses) or a productive defensive and regulation response and posture of the immune system. Mixed bits of normal DNA, cancer-laden DNA, circulating tumor DNA, circulating normal cells, circulating tumor cells, circulating immune defense cells, circulating immune inflammatory cells forming a moiety of normal and a moiety of mess. The challenge is to scavenge the mess and amplify the normal.

 

Immunoediting is a primary push-button feature that is definitely required to be hit when it comes to initiating immune defenses against cancer and an adaptation in favor of regression. As mentioned before that the tumor microenvironment is a “mixed bit” moiety, which includes elements of the immune system that can defend against circulating cancer cells and tumor growth. Personalized (Precision-Based) cancer vaccines must become the primary form of treatment in this case. Current treatment regimens in conventional therapy destroy immune defenses and regulation and create more serious complications observed in tumor progression, metastasis and survival. Commonly resistance to chemotherapeutic agents is observed. These personalized treatments will be developed in concert with cancer hallmark analytics and immunocentrics affinity and selection mapping. This mapping will demonstrate molecular pathway interface and HLA compatibility and adaptation with patientcentricity.

References:

 

https://www.linkedin.com/pulse/immunoediting-cancer-landscape-john-catanzaro/

 

https://www.cell.com/cell/fulltext/S0092-8674(16)31609-9

 

https://www.researchgate.net/publication/309432057_Circulating_tumor_cell_clusters_What_we_know_and_what_we_expect_Review

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4190561/

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5840207/

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5593672/

 

https://www.frontiersin.org/articles/10.3389/fimmu.2018.00414/full

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5593672/

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4190561/

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4388310/

 

https://www.linkedin.com/pulse/cancer-hallmark-analytics-omics-data-pathway-studio-review-catanzaro/

 

Read Full Post »


Nanostraws Developed at Stanford Sample a Cell’s Contents without Damage

Reporter: Irina Robu, PhD

Cells within our bodies change over time and divide, with thousands of chemical reactions happening within cell daily. Nicholas Melosh, Associate Professor of Materials Science and Engineering, developed a new, non-destructive system for sampling cells with nanoscale straws which could help uncover mysteries about how cells function.

Currently, cells are sampled via lysing which ruptures the cell membrane which means that it can’t ever be sampled again. The sample system that Dr. Melosh invented banks on, on tiny tubes 600 times smaller than a strand of hair that allow researchers to sample a single cell at a time. The nanostraws penetrate a cell’s outer membrane, without damaging it, and draw out proteins and genetic material from the cell’s salty interior.

The Nanostraw sampling technique, according to Melosh, will knowingly impact our understanding of cell development and could result to much safer and operational medical therapies because the technique allows for long term, non-destructive monitoring. The sampling technique could also inform cancer treatments and answer questions about why some cancer cells are resistant to chemotherapy while others are not. The sampling platform on which the nanostraws are grown is tiny, similar to the size of a gumball. It’s called the Nanostraw Extraction (NEX) sampling system, and it was designed to mimic biology itself.

The goal of developing this technology was to make an impact in medical biology by providing a platform that any lab could build.

SOURCE

http://news.stanford.edu/2017/02/20/minuscule-nanostraws-sample-cells-contents-without-damage

Read Full Post »


Topical Solution for Combination Oncology Drug Therapy: Patch that delivers Drug, Gene, and Light-based Therapy to Tumor

Reporter: Aviva Lev-Ari, PhD, RN

 

Self-assembled RNA-triple-helix hydrogel scaffold for microRNA modulation in the tumour microenvironment

Affiliations

  1. Massachusetts Institute of Technology, Institute for Medical Engineering and Science, Harvard-MIT Division for Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
    • João Conde,
    • Nuria Oliva,
    • Mariana Atilano,
    • Hyun Seok Song &
    • Natalie Artzi
  2. School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
    • João Conde
  3. Grup dEnginyeria de Materials, Institut Químic de Sarrià-Universitat Ramon Llull, Barcelona 08017, Spain
    • Mariana Atilano
  4. Division of Bioconvergence Analysis, Korea Basic Science Institute, Yuseong, Daejeon 169-148, Republic of Korea
    • Hyun Seok Song
  5. Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
    • Natalie Artzi
  6. Department of Medicine, Biomedical Engineering Division, Brigham and Womens Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
    • Natalie Artzi

Contributions

J.C. and N.A. conceived the project and designed the experiments. J.C., N.O., H.S.S. and M.A. performed the experiments, collected and analysed the data. J.C. and N.A. co-wrote the manuscript. All authors discussed the results and reviewed the manuscript.

Nature Materials
15,
353–363
(2016)
doi:10.1038/nmat4497
Received
22 April 2015
Accepted
26 October 2015
Published online
07 December 2015

The therapeutic potential of miRNA (miR) in cancer is limited by the lack of efficient delivery vehicles. Here, we show that a self-assembled dual-colour RNA-triple-helix structure comprising two miRNAs—a miR mimic (tumour suppressor miRNA) and an antagomiR (oncomiR inhibitor)—provides outstanding capability to synergistically abrogate tumours. Conjugation of RNA triple helices to dendrimers allows the formation of stable triplex nanoparticles, which form an RNA-triple-helix adhesive scaffold upon interaction with dextran aldehyde, the latter able to chemically interact and adhere to natural tissue amines in the tumour. We also show that the self-assembled RNA-triple-helix conjugates remain functional in vitro and in vivo, and that they lead to nearly 90% levels of tumour shrinkage two weeks post-gel implantation in a triple-negative breast cancer mouse model. Our findings suggest that the RNA-triple-helix hydrogels can be used as an efficient anticancer platform to locally modulate the expression of endogenous miRs in cancer.

SOURCE

http://www.nature.com/nmat/journal/v15/n3/abs/nmat4497.html#author-information

 

 

Patch that delivers drug, gene, and light-based therapy to tumor sites shows promising results

In mice, device destroyed colorectal tumors and prevented remission after surgery.

Helen Knight | MIT News Office
July 25, 2016

Approximately one in 20 people will develop colorectal cancer in their lifetime, making it the third-most prevalent form of the disease in the U.S. In Europe, it is the second-most common form of cancer.

The most widely used first line of treatment is surgery, but this can result in incomplete removal of the tumor. Cancer cells can be left behind, potentially leading to recurrence and increased risk of metastasis. Indeed, while many patients remain cancer-free for months or even years after surgery, tumors are known to recur in up to 50 percent of cases.

Conventional therapies used to prevent tumors recurring after surgery do not sufficiently differentiate between healthy and cancerous cells, leading to serious side effects.

In a paper published today in the journal Nature Materials, researchers at MIT describe an adhesive patch that can stick to the tumor site, either before or after surgery, to deliver a triple-combination of drug, gene, and photo (light-based) therapy.

Releasing this triple combination therapy locally, at the tumor site, may increase the efficacy of the treatment, according to Natalie Artzi, a principal research scientist at MIT’s Institute for Medical Engineering and Science (IMES) and an assistant professor of medicine at Brigham and Women’s Hospital, who led the research.

The general approach to cancer treatment today is the use of systemic, or whole-body, therapies such as chemotherapy drugs. But the lack of specificity of anticancer drugs means they produce undesired side effects when systemically administered.

What’s more, only a small portion of the drug reaches the tumor site itself, meaning the primary tumor is not treated as effectively as it should be.

Indeed, recent research in mice has found that only 0.7 percent of nanoparticles administered systemically actually found their way to the target tumor.

“This means that we are treating both the source of the cancer — the tumor — and the metastases resulting from that source, in a suboptimal manner,” Artzi says. “That is what prompted us to think a little bit differently, to look at how we can leverage advancements in materials science, and in particular nanotechnology, to treat the primary tumor in a local and sustained manner.”

The researchers have developed a triple-therapy hydrogel patch, which can be used to treat tumors locally. This is particularly effective as it can treat not only the tumor itself but any cells left at the site after surgery, preventing the cancer from recurring or metastasizing in the future.

Firstly, the patch contains gold nanorods, which heat up when near-infrared radiation is applied to the local area. This is used to thermally ablate, or destroy, the tumor.

These nanorods are also equipped with a chemotherapy drug, which is released when they are heated, to target the tumor and its surrounding cells.

Finally, gold nanospheres that do not heat up in response to the near-infrared radiation are used to deliver RNA, or gene therapy to the site, in order to silence an important oncogene in colorectal cancer. Oncogenes are genes that can cause healthy cells to transform into tumor cells.

The researchers envision that a clinician could remove the tumor, and then apply the patch to the inner surface of the colon, to ensure that no cells that are likely to cause cancer recurrence remain at the site. As the patch degrades, it will gradually release the various therapies.

The patch can also serve as a neoadjuvant, a therapy designed to shrink tumors prior to their resection, Artzi says.

When the researchers tested the treatment in mice, they found that in 40 percent of cases where the patch was not applied after tumor removal, the cancer returned.

But when the patch was applied after surgery, the treatment resulted in complete remission.

Indeed, even when the tumor was not removed, the triple-combination therapy alone was enough to destroy it.

The technology is an extraordinary and unprecedented synergy of three concurrent modalities of treatment, according to Mauro Ferrari, president and CEO of the Houston Methodist Research Institute, who was not involved in the research.

“What is particularly intriguing is that by delivering the treatment locally, multimodal therapy may be better than systemic therapy, at least in certain clinical situations,” Ferrari says.

Unlike existing colorectal cancer surgery, this treatment can also be applied in a minimally invasive manner. In the next phase of their work, the researchers hope to move to experiments in larger models, in order to use colonoscopy equipment not only for cancer diagnosis but also to inject the patch to the site of a tumor, when detected.

“This administration modality would enable, at least in early-stage cancer patients, the avoidance of open field surgery and colon resection,” Artzi says. “Local application of the triple therapy could thus improve patients’ quality of life and therapeutic outcome.”

Artzi is joined on the paper by João Conde, Nuria Oliva, and Yi Zhang, of IMES. Conde is also at Queen Mary University in London.

SOURCE

http://news.mit.edu/2016/patch-delivers-drug-gene-light-based-therapy-tumor-0725

Other related articles published in thie Open Access Online Scientific Journal include the following:

The Development of siRNA-Based Therapies for Cancer

Author: Ziv Raviv, PhD

https://pharmaceuticalintelligence.com/2013/05/09/the-development-of-sirna-based-therapies-for-cancer/

 

Targeted Liposome Based Delivery System to Present HLA Class I Antigens to Tumor Cells: Two papers

Reporter: Stephen J. Williams, Ph.D.

https://pharmaceuticalintelligence.com/2016/07/20/targeted-liposome-based-delivery-system-to-present-hla-class-i-antigens-to-tumor-cells-two-papers/

 

Blast Crisis in Myeloid Leukemia and the Activation of a microRNA-editing Enzyme called ADAR1

Curator: Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2016/06/10/blast-crisis-in-myeloid-leukemia-and-the-activation-of-a-microrna-editing-enzyme-called-adar1/

 

First challenge to make use of the new NCI Cloud Pilots – Somatic Mutation Challenge – RNA: Best algorithms for detecting all of the abnormal RNA molecules in a cancer cell

Reporter: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2016/07/17/first-challenge-to-make-use-of-the-new-nci-cloud-pilots-somatic-mutation-challenge-rna-best-algorithms-for-detecting-all-of-the-abnormal-rna-molecules-in-a-cancer-cell/

 

miRNA Therapeutic Promise

Curator: Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2016/05/01/mirna-therapeutic-promise/

Read Full Post »


New method for 3D imaging of brain tumors

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

Third-Harmonic Generation Microscopy Provides In Situ Brain Tumor Imaging

AMSTERDAM, Netherlands, April 25, 2015 — A technique involving third-harmonic generation microscopy could allow neurosurgeons to image and assess brain tumor boundaries during surgery, providing optical biopsies in near-real time and increasing the accuracy of tissue removal.

Pathologists typically use staining methods, in which chemicals like hematoxylin and eosin turn different tissue components blue and red, revealing its structure and whether there are any tumor cells. A definitive diagnosis can take up to 24 hours, meaning surgeons may not realize some cancerous tissue has escaped from their attention until after surgery — requiring a second operation and more risk.

Tissue from a patient diagnosed with low-grade glioma.

Tissue from a patient diagnosed with low-grade glioma. The green image is taken with the new method, while the pink uses conventional hematoxylin and eosin staining. From the upper left to the lower right, both images show increasing cell density due to more tumor tissue. The insets reveal the high density of tumor cells. Courtesy of N.V. Kuzmin et al./VU University Amsterdam.

Brain tumors — specifically glial brain tumors — are often spread out and mixed in with the healthy tissue, presenting a particular challenge. Surgery, irradiation and chemotherapy often cause substantial collateral damage to the surrounding brain tissue.

Now researchers from VU University Amsterdam, led by professor Marloes Groot, have demonstrated a label-free optical method for imaging cancerous brain tissue. They were able to produce most images in under a minute; smaller ones took <1 s, while larger images of a few square millimeters took 5 min.

The study involved firing short, 200-fs, 1200-nm laser pulses into the tissue. When three photons converged at the same time and place, the photons interacted with the nonlinear optical properties of the tissue. Through the phenomena of third harmonic generation, the interactions produced a single 400- or 600-nm photon (in the case of third or second harmonic generation, respectively).

The shorter-wavelength photon scatters in the tissue, and when it reaches a detector — in this case a high-sensitivity GaAsP photomultiplier tube — it reveals what the tissue looks like inside. The resulting images enabled clear recognition of cellularity, nuclear pleomorphism and rarefaction of neuropil in the tissue.

While this technique has been used in other applications — to image insects and fish embryos, for example — the researchers said this is the first time it’s been used to analyze glial brain tumors.

Groot and her team are now developing a handheld device for tumor border detection during surgery. The incoming laser pulses can only reach a depth of about 100 μm into the tissue currently; to reach further, Groot envisions attaching a needle that can pierce the tissue and deliver photons deeper.

The research was published in Biomedical Optics Express, a publication of The Optical Society (OSA) (doi: 10.1364/boe.7.001889).

 

Third harmonic generation imaging for fast, label-free pathology of human brain tumors

Biomedical Optics Express 2016  7(5):1889-1904    doi: 10.1364/BOE.7.001889

In brain tumor surgery, recognition of tumor boundaries is key. However, intraoperative assessment of tumor boundaries by the neurosurgeon is difficult. Therefore, there is an urgent need for tools that provide the neurosurgeon with pathological information during the operation. We show that third harmonic generation (THG) microscopy provides label-free, real-time images of histopathological quality; increased cellularity, nuclear pleomorphism, and rarefaction of neuropil in fresh, unstained human brain tissue could be clearly recognized. We further demonstrate THG images taken with a GRIN objective, as a step toward in situ THG microendoscopy of tumor boundaries. THG imaging is thus a promising tool for optical biopsies.

 

Glial tumors (gliomas) account for almost 80% of the tumors originating from brain tissue. The vast majority of these tumors are so-called ‘diffuse gliomas’ as they show very extensive (‘diffuse’) growth into the surrounding brain parenchyma. With surgical resection, irradiation, and/or chemotherapy it is impossible to eliminate all glioma cells without serious damage to the brain tissue. As a consequence, until now, patients with a diffuse glioma have had a poor prognosis, a situation which strongly contributes to the fact that brain tumor patients experience more years of life lost than patients with any other type of cancer [1,2].

Meanwhile it has also been demonstrated that the prognosis of patients with a diffuse glioma correlates with the extent of resection [3–5]. During brain surgery, however, it is extremely difficult for the neurosurgeon to determine the boundary of the tumor, i.e. whether a brain area contains tumor cells or not. If the neurosurgeon could have histopathological information on the tumor boundaries during brain surgery, then recognition of these tumor boundaries and with that, the surgical resection, could be significantly improved.

Occasionally, intra-operative analysis using hematoxylin-and-eosin (H&E) stained sections of snap-frozen material or smear preparations is performed by the pathologist to help establish brain tumor boundaries, but this procedure only allows analysis of small, selected regions, can only be performed on tissue fragments that are already resected, and is rather time consuming (frozen section diagnosis) or does not allow analysis of tumor in the histological context (smear preparations). Fluorescence imaging techniques are increasingly used during surgery [6,7] but are associated with several drawbacks, such as heterogeneous delivery and nonspecific staining [8,9]. In particular, low-grade gliomas and normal brain tissue have an intact blood-brain barrier and take up little circulating dye [10–12]. Alternative techniques are therefore required, that can detect the presence of tumor cells in tissue without fluorescent labels and with a speed that enables ‘live’ feedback to the surgeon while he/she operates.

The past year has seen exciting new developments in which optical coherence tomography [13] and stimulated Raman microscopy [14,15] were reported to reliably detect tumor tissue in the brain of human glioma patients, and a handheld Raman spectroscopy device was even implemented intra-surgical to assess brain tissue prior to excision [16]. These techniques are especially sensitive in densely tumor-infiltrated areas, and for the Raman spectroscopy device study a sensitivity limit of 17 tumor cells in an area of 150 × 150 μm2 was reported. The discriminating power of the Raman techniques is based on subtle differences in the vibrational spectra of tumor tissue and healthy tissue, and they require extensive comparison of experimental spectra against libraries of reference spectra. A technique capable of directly visualizing the classical histopathological hallmark criteria currently used by pathologists for classification of tumor tissue could potentially be even more reliable and make the transition from the current practice—histopathological analysis of fixated tissue—to in situ optical biopsy easier. Diffuse gliomas are histopathologically characterized by variably increased cellularity, nuclear pleomorphism and—especially in higher-grade neoplasms—brisk mitotic activity, microvascular proliferation, and necrosis. To visualize these features in live tissue, a technique that elucidates the morphology of tissue is required. In this context, third harmonic generation (THG) microscopy is a promising tool because of its capacity to visualize almost the full morphology of tissue. THG is a nonlinear optical process that relies on spatial variations of the third-order non-linear susceptibility χ(3) intrinsic to the tissue and (in the case of brain tissue) mainly arises from interfaces with lipid-rich molecules [17–27]. SHG signals arise from an optical nonlinear process involving non-centrosymmetric molecules present in, for example, microtubules and collagen. THG has been successfully applied to image unstained samples such as insect embryos, plant seeds and intact mammalian tissue [28], epithelial tissues [29–31], zebra fish embryos [32], and the zebra fish nervous system [33]. In brain tissue of mice, augmented by co-recording of SHG signals, THG was shown to visualize cells, nuclei, the inner and outer contours of axons, blood cells, and vessels, resulting in the visualization of both gray and white matter (GM and WM) as well as vascularization, up to a depth of 350 μm [24,26]. Here, we explore the potential of THG and SHG imaging for real time analysis of ex-vivo human brain tissue in the challenging cases of diffuse tumor invasion in low-grade brain tumors as well as of high-grade gliomas and structurally normal brain tissues.

 

Multiphoton imaging

THG and SHG are nonlinear optical processes that may occur in tissue depending on the nonlinear susceptibility coefficients χ(3) and χ(2) of the tissue and upon satisfying phase matching conditions [17–19,21,23–27]. In the THG process, three incident photons are converted into one photon with triple energy and one third of the wavelength (Fig. 1(A)). In the SHG process, signals result from the conversion of an incident photon pair into one photon with twice the energy and half the wavelength. Two- and three photon excited fluorescence signals (2PF, 3PF) may simultaneously be generated by intrinsic proteins (Fig. 1(B)). As a result, a set of distinct (harmonic) and broadband (autofluorescence) spectral peaks is generated in the visible range. The imaging setup (Fig. 1(C)) to generate and collect these signals consisted of a commercial two-photon laser-scanning microscope (TriMScope I, LaVision BioTec GmbH) and a femtosecond laser source. The laser source was an optical parametric oscillator (Mira-OPO, APE) pumped at 810 nm by a Ti-sapphire oscillator (Coherent Chameleon Ultra II). The OPO generates 200 fs pulses at 1200 nm with a repetition rate of 80 MHz. We selected this wavelength as it falls in the tissue transparency window, providing deeper penetration and reduced photodamage compared to the 700–1000 nm range, as well as harmonic signals generated in the visible wavelength range, facilitating their collection and detection with conventional objectives and detectors. We focused the OPO beam on the sample using a 25 × /1.10 (Nikon APO LWD) water-dipping objective (MO). The 1200 nm beam focal spot size on the sample was dlateral ~0.7 μm and daxial ~4.1 μm. It was measured with 0.175 μm fluorescent microspheres (see Section 3.4) yielding two- and three-photon resolution values Δ2P,lateral ~0.5 μm, Δ2P,axial ~2.9 μm, Δ3P,lateral ~0.4 μm, and Δ3P,axial ~2.4 μm. Two high-sensitivity GaAsP photomultiplier tubes (PMT, Hamamatsu H7422-40) equipped with narrowband filters at 400 nm and 600 nm were used to collect the THG and SHG signals, respectively, as a function of position of the focus in the sample. The signals were filtered from the 1200 nm fundamental photons by a dichroic mirror (Chroma T800LPXRXT, DM1), split into SHG and THG channels by a dichroic mirror (Chroma T425LPXR, DM2), and passed through narrow-band interference filters (F) for SHG (Chroma D600/10X) and THG (Chroma Z400/10X) detection. The efficient back-scattering of the harmonic signals allowed for their detection in epi-direction. The laser beam was transversely scanned over the sample by a pair of galvo mirrors (GM). THG and SHG modalities are intrinsically confocal and therefore provide direct depth sectioning. We obtained a full 3D image of the tissue volume by scanning the microscope objective with a stepper motor in the vertical (z) direction. The mosaic imaging of the sample was performed by transverse (xy) scanning of the motorized translation stage. Imaging data was acquired with the TriMScope I software (“Imspector Pro”); image stacks were stored in 16-bit tiff-format and further processed and analyzed with “ImageJ” software (ver. 1.49m, NIH, USA). All images were processed with logarithmic contrast enhancement.

Fig. 1 THG/SHG microscopy for brain tissue imaging. (A) Energy level diagram of the second (SHG) and third (THG) harmonic generation process. (B) Energy level diagram of the two- (2PF) and three-photon (3PF) excited auto-fluorescence process. (C) Multiphoton microscope setup: Laser producing 200 fs pulses at 1200 nm; GM – X-Y galvo-scanner mirrors; SL – scan lens; TL – tube lens; MO – microscope objective; DM1 – dichroic mirror reflecting back-scattered THG/SHG photons to the PMT detectors; DM2 – dichroic mirror splitting SHG and THG channels; F – narrow-band SHG and THG interference filters; L – focusing lenses; PMT – photomultiplier tube detectors. (D) Infrared photons (white arrow) are focused deep in the brain tissue, converted to THG (green) and SHG (red) photons, scattered back (green/red arrows) and epi-detected. The nonlinear optical processes result in label-free contrast images with sub-cellular resolution and intrinsic depth sectioning. (E and F) Freshly-excised low-grade (E) and high-grade (F) glioma tissue samples in artificial cerebrospinal fluid (ACSF) in a Petri dish with a millimeter paper underneath for scale. (G) An agar-embedded tumor tissue sample under 0.17 mm glass cover slip with the microscope objective (MO) on top.   Download Full Size | PPT Slide

Endomicroscopy imaging

For endomicroscopic imaging we used a commercial high-numerical-aperture (NA) multi-element micro-objective lens (GT-MO-080-018-810, GRINTECH) composed of a plano-convex lens and two GRaded INdex (GRIN) lenses with aberration compensation, object NA = 0.80 and object working distance 200 µm (in water), image NA = 0.18 and image working distance 200 µm (in air), magnification × 4.8 and field-of-view diameter of 200 μm. The GRIN lenses and the plano-convex lens were mounted in a waterproof stainless steel housing with an outer diameter of 1.4 mm and a total length of 7.5 mm. Originally designed for a wavelength range of 800–900 nm [36–41], this micro-objective lens was used for focusing of 1200 nm femtosecond pulses and collection of back-scattered harmonic and fluorescence photons. A coupling lens with f = 40 mm (NA = 0.19, Qioptiq, ARB2 NIR, dia. 25 mm) focused the scanned laser beam in the image plane of the micro-objective lens and forwarded the epi-detected harmonic and fluorescence photons to the PMTs.

We characterized the lateral (x) and axial (z) resolution of the micro-objective lens by 3D imaging of fluorescence microspheres (PS-Speck Microscope Point Source Kit, P7220, Molecular Probes). We used “blue” and “deep red” microspheres, 0.175 ± 0.005 μm in diameter, with excitation/emission maxima at 360/440 nm and 630/660 nm to obtain three-photon (3P) and two-photon (2P) point spread function (PSF) profiles. The excitation wavelength was 1200 nm, and fluorescence signals were detected in the 400 ± 5 nm (3P) and 600 ± 5 nm (2P) spectral windows, just as in the brain tissue imaging experiments. 1 μL of “blue” and “deep red” sphere suspensions were applied to a propanol-cleaned 75 × 26 × 1 mm3 glass slide. The mixed microsphere suspension was left to dry for 20 min and was then imaged with the micro-objective lens via a water immersion layer. The assembly of the coupling lens and the micro-objective lens was vertically (z) scanned with a step of 0.5 μm, and stacks of two-/three-photon images were recorded. The line profiles were then taken over the lateral (xy) images of the fluorescent spheres with maximal intensity (in focus), and fluorescence counts were plotted as function of the lateral coordinate (x). The axial (z) scan values of the two- and three-photon fluorescence signals were acquired by averaging of the total fluorescence counts of the corresponding spheres and were plotted as function of the axial coordinate (z). Lateral (x) and axial (z) 2P/3P points were then fitted with Gaussian functions and full width at half-maximum (FWHM) values were measured.

……. Results….  Conclusions

The results shown here provide the first evidence that—by applying the same microscopic criteria that are used by the pathologist, i.e. increased cellularity, nuclear pleomorphism, and rarefaction of neuropil—THG/SHG ex-vivo microscopy can be used to recognize the presence of diffuse infiltrative glioma in fresh, unstained human brain tissue. Images and a first diagnosis can be provided in seconds, with the ‘inspection mode’, by moving the sample under the scanning microscope (see Visualization 4 and Visualization 5), or in about 5 minutes if an area has to be inspected with sub-cellular detail. The sensitivity of THG to interfaces provides images with excellent contrast in which cell-by-cell variations are visualized. The quality of the images and the speed with which they can be recorded make THG a promising tool for quick assessment of the nature of excised tissue. Importantly, because THG/SHG images are very close to those of histological slides, we expect that the surgeon (or pathologist) will need very little additional training for adequate interpretation of the images. We are planning to construct a THG/SHG ex-vivo tabletop device consisting of a compact laser source and a laser-scanning microscope requiring a physical footprint of only 1 m2, to be placed in an operating room, enabling immediate feedback to the surgeon on the nature of excised tissue, during the operation. With this device, we will perform a quantitative study of the added value of rapid THG/SHG pathological feedback during surgery for the final success of the neurosurgery. Finally, we note that THG/SHG imaging does not induce artifacts associated with fixation, freezing, and staining; therefore, tissue fragments examined ex-vivo can still be used for subsequent immunochemical and/or molecular analysis.

The microendoscopy THG/SHG imaging results represent an important step toward the development of a THG/SHG-based bioptic needle, and show that the use of such a needle for in situ optical sampling for optimal resection of gliomas is indeed a viable prospect, as has been demonstrated also before for multi-photon microscopies [38,49–54]. Although there are several issues associated with the operation of a needle-like optical device, such as the fact that blood in the surgical cavity may obscure the view, and the fact that only small areas can be biopsied with a needle, it may be a valuable tool in cases where sparing healthy tissue is of such vital importance as in brain surgery. Therefore, the reasonably good quality of the THG images taken with the GRIN micro-objective shown here, together with the developments in the field of microendoscopy, warrant further development of THG/SHG into a true handheld device. This next step, a true handheld bioptic needle, requires an optical fiber to transport the light from a small footprint laser to the GRIN micro-objective, and a small 2D scanner unit, to enable placing the laser at a sufficient distance from the patient. Patient-safe irradiation levels for THG imaging will have to be determined but are expected to lie in the 10–50 mW range [55–58]. This implies that only minor optimization of signal collection efficiency needs to be achieved, because the images of Fig. 10 were measured with 50 mW incident power.

THG/SHG imaging thus holds great promise for improving surgical procedures, thereby reducing the need for second surgeries and the loss of function by excising non-infiltrated brain tissue, as well as improving survival and quality of life of the patients. In addition, the success in the challenging case of diffuse gliomas promises great potential of THG/SHG-based histological analysis for a much wider spectrum of diagnostic applications.

References and links

1. N. G. Burnet, S. J. Jefferies, R. J. Benson, D. P. Hunt, and F. P. Treasure, “Years of life lost (YLL) from cancer is an important measure of population burden–and should be considered when allocating research funds,” Br. J. Cancer 92(2), 241–245 (2005). [PubMed]  

2. J. A. Schwartzbaum, J. L. Fisher, K. D. Aldape, and M. Wrensch, “Epidemiology and molecular pathology of glioma,” Nat. Clin. Pract. Neurol. 2(9), 494–516 (2006). [CrossRef]   [PubMed]  

3. J. S. Smith, E. F. Chang, K. R. Lamborn, S. M. Chang, M. D. Prados, S. Cha, T. Tihan, S. Vandenberg, M. W. McDermott, and M. S. Berger, “Role of extent of resection in the long-term outcome of low-grade hemispheric gliomas,” J. Clin. Oncol. 26(8), 1338–1345 (2008). [CrossRef]   [PubMed]  

4. N. Sanai and M. S. Berger, “Glioma extent of resection and its impact on patient outcome,” Neurosurgery 62(4), 753–766 (2008). [CrossRef]   [PubMed]  

5. I. Y. Eyüpoglu, M. Buchfelder, and N. E. Savaskan, “Surgical resection of malignant gliomas-role in optimizing patient outcome,” Nat. Rev. Neurol. 9(3), 141–151 (2013). [CrossRef]  [PubMed]  

6. U. Pichlmeier, A. Bink, G. Schackert, and W. Stummer, “Resection and survival in glioblastoma multiforme: An RTOG recursive partitioning analysis of ALA study patients,” Neuro-oncol. 10(6), 1025–1034 (2008). [CrossRef]   [PubMed]  

7. W. Stummer, J. C. Tonn, C. Goetz, W. Ullrich, H. Stepp, A. Bink, T. Pietsch, and U. Pichlmeier, “5-Aminolevulinic Acid-Derived Tumor Fluorescence: The Diagnostic Accuracy of Visible Fluorescence Qualities as Corroborated by Spectrometry and Histology and Postoperative Imaging,” Neurosurgery 74(3), 310–320 (2014). [CrossRef]   [PubMed]  

….. more

Tables (1)

Tables Icon

Table 1 Pre-operative diagnoses and cell densities observed in the studied brain tissue samples by THG imaging and corresponding H&E histopathology.

Read Full Post »


Colon cancer and organoids

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

 

Guts and Glory

An open mind and collaborative spirit have taken Hans Clevers on a journey from medicine to developmental biology, gastroenterology, cancer, and stem cells.

By Anna Azvolinsky    http://www.the-scientist.com/?articles.view/articleNo/45580/title/Guts-and-Glory

Ihave had to talk a lot about my science recently and it’s made me think about how science works,” says Hans Clevers. “Scientists are trained to think science is driven by hypotheses, but for [my lab], hypothesis-driven research has never worked. Instead, it has been about trying to be as open-minded as possible—which is not natural for our brains,” adds the Utrecht University molecular genetics professor. “The human mind is such that it tries to prove it’s right, so pursuing a hypothesis can result in disaster. My advice to my own team and others is to not preformulate an answer to a scientific question, but just observe and never be afraid of the unknown. What has worked well for us is to keep an open mind and do the experiments. And find a collaborator if it is outside our niche.”

“One thing I have learned is that hypothesis-driven research tends not to be productive when you are in an unknown territory.”

Clevers entered medical school at Utrecht University in The Netherlands in 1978 while simultaneously pursuing a master’s degree in biology. Drawn to working with people in the clinic, Clevers had a training position in pediatrics lined up after medical school, but then mentors persuaded him to spend an additional year converting the master’s degree to a PhD in immunology. “At the end of that year, looking back, I got more satisfaction from the research than from seeing patients.” Clevers also had an aptitude for benchwork, publishing four papers from his PhD year. “They were all projects I had made up myself. The department didn’t do the kind of research I was doing,” he says. “Now that I look back, it’s surprising that an inexperienced PhD student could come up with a project and publish independently.”

Clevers studied T- and B-cell signaling; he set up assays to visualize calcium ion flux and demonstrated that the ions act as messengers to activate human B cells, signaling through antibodies on the cell surface. “As soon as the experiment worked, I got T cells from the lab next door and did the same experiment. That was my strategy: as soon as something worked, I would apply it elsewhere and didn’t stop just because I was a B-cell biologist and not a T-cell biologist. What I learned then, that I have continued to benefit from, is that a lot of scientists tend to adhere to a niche. They cling to these niches and are not that flexible. You think scientists are, but really most are not.”

Here, Clevers talks about promoting a collaborative spirit in research, the art of doing a pilot experiment, and growing miniature organs in a dish.

Clevers Creates

Re-search? Clevers was born in Eindhoven, in the south of The Netherlands. The town was headquarters to Philips Electronics, where his father worked as a businessman, and his mother took care of Clevers and his three brothers. Clevers did well in school but his passion was sports, especially tennis and field hockey, “a big thing in Holland.” Then in 1975, at age 18, he moved to Utrecht University, where he entered an intensive, biology-focused program. “I knew I wanted to be a biology researcher since I was young. In Dutch, the word for research is ‘onderzoek’ and I knew the English word ‘research’ and had wondered why there was the ‘re’ in the word, because I wanted to search but I didn’t want to do re-search—to find what someone else had already found.”

Opportunity to travel. “I was very disappointed in my biology studies, which were old-fashioned and descriptive,” says Clevers. He thought medicine might be more interesting and enrolled in medical school while still pursuing a master’s degree in biology at Utrecht. For the master’s, Clevers had to do three rotations. He spent a year at the International Laboratory for Research on Animal Diseases (ILRAD) in Nairobi, Kenya, and six months in Bethesda, Maryland, at the National Institutes of Health. “Holland is really small, so everyone travels.” Clevers saw those two rotations more as travel explorations. In Nairobi, he went on safaris and explored the country in Land Rovers borrowed from the institute. While in Maryland in 1980, Clevers—with the consent of his advisor, who thought it was a good idea for him to get a feel for the U.S.—flew to Portland, Oregon, and drove back to Boston with a musician friend along the Canadian border. He met the fiancé of political activist and academic Angela Davis in New York City and even stayed in their empty apartment there.

Life and lab lessons. Back in Holland, Clevers joined Rudolf Eugène Ballieux’s lab at Utrecht University to pursue his PhD, for which he studied immune cell signaling. “I didn’t learn much science from him, but I learned that you always have to create trust and to trust people around you. This became a major theme in my own lab. We don’t distrust journals or reviewers or collaborators. We trust everyone and we share. There will be people who take advantage, but there have only been a few of those. So I learned from Ballieux to give everyone maximum trust and then change this strategy only if they fail that trust. We collaborate easily because we give out everything and we also easily get reagents and tools that we may need. It’s been valuable to me in my career. And it is fun!”

Clevers Concentrates

On a mission. “Once I decided to become a scientist, I knew I needed to train seriously. Up to that point, I was totally self-trained.” From an extensive reading of the immunology literature, Clevers became interested in how T cells recognize antigens, and headed off to spend a postdoc studying the problem in Cox Terhorst’s lab at Dana-Farber Cancer Institute in Boston. “Immunology was young, but it was very exciting and there was a lot to discover. I became a professional scientist there and experienced how tough science is.” In 1988, Clevers cloned and characterized the gene for a component of the T-cell receptor (TCR) called CD3-epsilon, which binds antigen and activates intracellular signaling pathways.

On the fast track in Holland. Clevers returned to Utrecht University in 1989 as a professor of immunology. Within one month of setting up his lab, he had two graduate students and a technician, and the lab had cloned the first T cell–specific transcription factor, which they called TCF-1, in human T cells. When his former thesis advisor retired, Clevers was asked, at age 33, to become head of the immunology department. While the appointment was high-risk for him and for the department, Clevers says, he was chosen because he was good at multitasking and because he got along well with everyone.

Problem-solving strategy. “My strategy in research has always been opportunistic. One thing I have learned is that hypothesis-driven research tends not to be productive when you are in an unknown territory. I think there is an art to doing pilot experiments. So we have always just set up systems in which something happens and then you try and try things until a pattern appears and maybe you formulate a small hypothesis. But as soon as it turns out not to be exactly right, you abandon it. It’s a very open-minded type of research where you question whether what you are seeing is a real phenomenon without spending a year on doing all of the proper controls.”

Trial and error. Clevers’s lab found that while TCF-1 bound to DNA, it did not alter gene expression, despite the researchers’ tinkering with promoter and enhancer assays. “For about five years this was a problem. My first PhD students were leaving and they thought the whole TCF project was a failure,” says Clevers. His lab meanwhile cloned TCF homologs from several model organisms and made many reagents including antibodies against these homologs. To try to figure out the function of TCF-1, the lab performed a two-hybrid screen and identified components of the Wnt signaling pathway as binding partners of TCF-1. “We started to read about Wnt and realized that you study Wnt not in T cells but in frogs and flies, so we rapidly transformed into a developmental biology lab. We showed that we held the key for a major issue in developmental biology, the final protein in the Wnt cascade: TCF-1 binds b-catenin when b-catenin becomes available and activates transcription.” In 1996, Clevers published the mechanism of how the TCF-1 homolog in Xenopus embryos, called XTcf-3, is integrated into the Wnt signaling pathway.

Clevers Catapults

COURTESY OF HANS CLEVERS AND JEROEN HUIJBEN, NYMUS

3DCrypt building and colon cancer.

Clevers next collaborated with Bert Vogelstein’s lab at Johns Hopkins, linking TCF to Wnt signaling in colon cancer. In colon cancer cell lines with mutated forms of the tumor suppressor gene APC, the APC protein can’t rein in b-catenin, which accumulates in the cytoplasm, forms a complex with TCF-4 (later renamed TCF7L2) in the nucleus, and caninitiate colon cancer by changing gene expression. Then, the lab showed that Wnt signaling is necessary for self-renewal of adult stem cells, as mice missing TCF-4 do not have intestinal crypts, the site in the gut where stem cells reside. “This was the first time Wnt was shown to play a role in adults, not just during development, and to be crucial for adult stem cell maintenance,” says Clevers. “Then, when I started thinking about studying the gut, I realized it was by far the best way to study stem cells. And I also realized that almost no one in the world was studying the healthy gut. Almost everyone who researched the gut was studying a disease.” The main advantages of the murine model are rapid cell turnover and the presence of millions of stereotypic crypts throughout the entire intestine.

Against the grain. In 2007, Nick Barker, a senior scientist in the Clevers lab, identified the Wnt target gene Lgr5 as a unique marker of adult stem cells in several epithelial organs, including the intestine, hair follicle, and stomach. In the intestine, the gene codes for a plasma membrane protein on crypt stem cells that enable the intestinal epithelium to self-renew, but can also give rise to adenomas of the gut. Upon making mice with adult stem cell populations tagged with a fluorescent Lgr5-binding marker, the lab helped to overturn assumptions that “stem cells are rare, impossible to find, quiescent, and divide asymmetrically.”

On to organoids. Once the lab could identify adult stem cells within the crypts of the gut, postdoc Toshiro Sato discovered that a single stem cell, in the presence of Matrigel and just three growth factors, could generate a miniature crypt structure—what is now called an organoid. “Toshi is very Japanese and doesn’t always talk much,” says Clevers. “One day I had asked him, while he was at the microscope, if the gut stem cells were growing, and he said, ‘Yes.’ Then I looked under the microscope and saw the beautiful structures and said, ‘Why didn’t you tell me?’ and he said, ‘You didn’t ask.’ For three months he had been growing them!” The lab has since also grown mini-pancreases, -livers, -stomachs, and many other mini-organs.

Tumor Organoids. Clevers showed that organoids can be grown from diseased patients’ samples, a technique that could be used in the future to screen drugs. The lab is also building biobanks of organoidsderived from tumor samples and adjacent normal tissue, which could be especially useful for monitoring responses to chemotherapies. “It’s a similar approach to getting a bacterium cultured to identify which antibiotic to take. The most basic goal is not to give a toxic chemotherapy to a patient who will not respond anyway,” says Clevers. “Tumor organoids grow slower than healthy organoids, which seems counterintuitive, but with cancer cells, often they try to divide and often things go wrong because they don’t have normal numbers of chromosomes and [have] lots of mutations. So, I am not yet convinced that this approach will work for every patient. Sometimes, the tumor organoids may just grow too slowly.”

Selective memory. “When I received the Breakthrough Prize in 2013, I invited everyone who has ever worked with me to Amsterdam, about 100 people, and the lab organized a symposium where many of the researchers gave an account of what they had done in the lab,” says Clevers. “In my experience, my lab has been a straight line from cloning TCF-1 to where we are now. But when you hear them talk it was ‘Hans told me to try this and stop this’ and ‘Half of our knockout mice were never published,’ and I realized that the lab is an endless list of failures,” Clevers recalls. “The one thing we did well is that we would start something and, as soon as it didn’t look very good, we would stop it and try something else. And the few times when we seemed to hit gold, I would regroup my entire lab. We just tried a lot of things, and the 10 percent of what worked, those are the things I remember.”

Greatest Hits

  • Cloned the first T cell–specific transcription factor, TCF-1, and identified homologous genes in model organisms including the fruit fly, frog, and worm
  • Found that transcriptional activation by the abundant β-catenin/TCF-4 [TCF7L2] complex drives cancer initiation in colon cells missing the tumor suppressor protein APC
  • First to extend the role of Wnt signaling from developmental biology to adult stem cells by showing that the two Wnt pathway transcription factors, TCF-1 and TCF-4, are necessary for maintaining the stem cell compartments in the thymus and in the crypt structures of the small intestine, respectively
  • Identified Lgr5 as an adult stem cell marker of many epithelial stem cells including those of the colon, small intestine, hair follicle, and stomach, and found that Lgr5-expressing crypt cells in the small intestine divide constantly and symmetrically, disproving the common belief that stem cell division is asymmetrical and uncommon
  • Established a three-dimensional, stable model, the “organoid,” grown from adult stem cells, to study diseased patients’ tissues from the gut, stomach, liver, and prostate
 Regenerative Medicine Comes of Age   
“Anti-Aging Medicine” Sounds Vaguely Disreputable, So Serious Scientists Prefer to Speak of “Regenerative Medicine”
  • Induced pluripotent stem cells (iPSCs) and genome-editing techniques have facilitated manipulation of living organisms in innumerable ways at the cellular and genetic levels, respectively, and will underpin many aspects of regenerative medicine as it continues to evolve.

    An attitudinal change is also occurring. Experts in regenerative medicine have increasingly begun to embrace the view that comprehensively repairing the damage of aging is a practical and feasible goal.

    A notable proponent of this view is Aubrey de Grey, Ph.D., a biomedical gerontologist who has pioneered an regenerative medicine approach called Strategies for Engineered Negligible Senescence (SENS). He works to “develop, promote, and ensure widespread access to regenerative medicine solutions to the disabilities and diseases of aging” as CSO and co-founder of the SENS Research Foundation. He is also the editor-in-chief of Rejuvenation Research, published by Mary Ann Liebert.

    Dr. de Grey points out that stem cell treatments for age-related conditions such as Parkinson’s are already in clinical trials, and immune therapies to remove molecular waste products in the extracellular space, such as amyloid in Alzheimer’s, have succeeded in such trials. Recently, there has been progress in animal models in removing toxic cells that the body is failing to kill. The most encouraging work is in cancer immunotherapy, which is rapidly advancing after decades in the doldrums.

    Many damage-repair strategies are at an  early stage of research. Although these strategies look promising, they are handicapped by a lack of funding. If that does not change soon, the scientific community is at risk of failing to capitalize on the relevant technological advances.

    Regenerative medicine has moved beyond boutique applications. In degenerative disease, cells lose their function or suffer elimination because they harbor genetic defects. iPSC therapies have the potential to be curative, replacing the defective cells and eliminating symptoms in their entirety. One of the biggest hurdles to commercialization of iPSC therapies is manufacturing.

  • Building Stem Cell Factories

    Cellular Dynamics International (CDI) has been developing clinically compatible induced pluripotent stem cells (iPSCs) and iPSC-derived human retinal pigment epithelial (RPE) cells. CDI’s MyCell Retinal Pigment Epithelial Cells are part of a possible therapy for macular degeneration. They can be grown on bioengineered, nanofibrous scaffolds, and then the RPE cell–enriched scaffolds can be transplanted into patients’ eyes. In this pseudo-colored image, RPE cells are shown growing over the nanofibers. Each cell has thousands of “tongue” and “rod” protrusions that could naturally support rod and cone cells in the eye.

    “Now that an infrastructure is being developed to make unlimited cells for the tools business, new opportunities are being created. These cells can be employed in a therapeutic context, and they can be used to understand the efficacy and safety of drugs,” asserts Chris Parker, executive vice president and CBO, Cellular Dynamics International (CDI). “CDI has the capability to make a lot of cells from a single iPSC line that represents one person (a capability termed scale-up) as well as the capability to do it in parallel for multiple individuals (a capability termed scale-out).”

    Minimally manipulated adult stem cells have progressed relatively quickly to the clinic. In this scenario, cells are taken out of the body, expanded unchanged, then reintroduced. More preclinical rigor applies to potential iPSC therapy. In this case, hematopoietic blood cells are used to make stem cells, which are manufactured into the cell type of interest before reintroduction. Preclinical tests must demonstrate that iPSC-derived cells perform as intended, are safe, and possess little or no off-target activity.

    For example, CDI developed a Parkinsonian model in which iPSC-derived dopaminergic neurons were introduced to primates. The model showed engraftment and enervation, and it appeared to be free of proliferative stem cells.

    • “You will see iPSCs first used in clinical trials as a surrogate to understand efficacy and safety,” notes Mr. Parker. “In an ongoing drug-repurposing trial with GlaxoSmithKline and Harvard University, iPSC-derived motor neurons will be produced from patients with amyotrophic lateral sclerosis and tested in parallel with the drug.” CDI has three cell-therapy programs in their commercialization pipeline focusing on macular degeneration, Parkinson’s disease, and postmyocardial infarction.

    • Keeping an Eye on Aging Eyes

      The California Project to Cure Blindness is evaluating a stem cell–based treatment strategy for age-related macular degeneration. The strategy involves growing retinal pigment epithelium (RPE) cells on a biostable, synthetic scaffold, then implanting the RPE cell–enriched scaffold to replace RPE cells that are dying or dysfunctional. One of the project’s directors, Dennis Clegg, Ph.D., a researcher at the University of California, Santa Barbara, provided this image, which shows stem cell–derived RPE cells. Cell borders are green, and nuclei are red.

      The eye has multiple advantages over other organ systems for regenerative medicine. Advanced surgical methods can access the back of the eye, noninvasive imaging methods can follow the transplanted cells, good outcome parameters exist, and relatively few cells are needed.

      These advantages have attracted many groups to tackle ocular disease, in particular age-related macular degeneration, the leading cause of blindness in the elderly in the United States. Most cases of age-related macular degeneration are thought to be due to the death or dysfunction of cells in the retinal pigment epithelium (RPE). RPE cells are crucial support cells for the rods, cones, and photoreceptors. When RPE cells stop working or die, the photoreceptors die and a vision deficit results.

      A regenerated and restored RPE might prevent the irreversible loss of photoreceptors, possibly via the the transplantation of functionally polarized RPE monolayers derived from human embryonic stem cells. This approach is being explored by the California Project to Cure Blindness, a collaborative effort involving the University of Southern California (USC), the University of California, Santa Barbara (UCSB), the California Institute of Technology, City of Hope, and Regenerative Patch Technologies.

      The project, which is funded by the California Institute of Regenerative Medicine (CIRM), started in 2010, and an IND was filed early 2015. Clinical trial recruitment has begun.

      One of the project’s leaders is Dennis Clegg, Ph.D., Wilcox Family Chair in BioMedicine, UCSB. His laboratory developed the protocol to turn undifferentiated H9 embryonic stem cells into a homogenous population of RPE cells.

      “These are not easy experiments,” remarks Dr. Clegg. “Figuring out the biology and how to make the cell of interest is a challenge that everyone in regenerative medicine faces. About 100,000 RPE cells will be grown as a sheet on a 3 × 5 mm biostable, synthetic scaffold, and then implanted in the patients to replace the cells that are dying or dysfunctional. The idea is to preserve the photoreceptors and to halt disease progression.”

      Moving therapies such as this RPE treatment from concept to clinic is a huge team effort and requires various kinds of expertise. Besides benefitting from Dr. Clegg’s contribution, the RPE project incorporates the work of Mark Humayun, M.D., Ph.D., co-director of the USC Eye Institute and director of the USC Institute for Biomedical Therapeutics and recipient of the National Medal of Technology and Innovation, and David Hinton, Ph.D., a researcher at USC who has studied how actvated RPE cells can alter the local retinal microenvironment.

Read Full Post »


Curbing Cancer Cell Growth & Metastasis-on-a-Chip’ Models Cancer’s Spread

Curator: Larry H. Bernstein, MD, FCAP

 

New Approach to Curbing Cancer Cell Growth

http://www.technologynetworks.com/Metabolomics/news.aspx?ID=189342

Using a new approach, scientists at The Scripps Research Institute (TSRI) and collaborating institutions have discovered a novel drug candidate that could be used to treat certain types of breast cancer, lung cancer and melanoma.

The new study focused on serine, one of the 20 amino acids (protein building blocks) found in nature. Many types of cancer require synthesis of serine to sustain rapid, constant and unregulated growth.

To find a drug candidate that interfered with this pathway, the team screened a large library of compounds from a variety of sources, searching for molecules that inhibited a specific enzyme known as 3-phosphoglycerate dehydrogenase (PHGDH), which is responsible for the first committed step in serine biosynthesis.

“In addition to discovering an inhibitor that targets cancer metabolism, we also now have a tool to help answer interesting questions about serine metabolism,” said Luke L. Lairson, assistant professor of chemistry at TSRI and principal investigator of cell biology at the California Institute for Biomedical Research (CALIBR).

Lairson was senior author of the study, published recently in the Proceedings of the National Academy of Sciences (PNAS), with Lewis Cantley of Weill Cornell Medical College and Costas Lyssiotis of the University of Michigan.

Addicted to Serine

Serine is necessary for nucleotide, protein and lipid biosynthesis in all cells. Cells use two main routes for acquiring serine: through import from the extracellular environment or through conversion of 3-phosphoglycerate (a glycolytic intermediate) by PHGDH.

“Since the late 1950s, it has been known that cancer cells use the process of aerobic glycolysis to generate metabolites needed for proliferative growth,” said Lairson.

This process can lead to an overproduction of serine. The genetic basis for this abundance had remained mysterious until recently, when it was demonstrated that some cancers acquire mutations that increased the expression of PHGDH; reducing PHGDH in these “serine-addicted” cancer cells also inhibited their growth.

The labs of Lewis C. Cantley at Weill Cornell Medical College (in work published in Nature Genetics) and David Sabatini at the Whitehead Institute (in work published in Nature) suggested PHGDH as a potential drug target for cancer types that overexpress the enzyme.

Lairson and colleagues hypothesized that a small molecule drug candidate that inhibited PHGDH could interfere with cancer metabolism and point the way to the development of an effective cancer therapeutic. Importantly, this drug candidate would be inactive against normal cells because they would be able to import enough serine to support ordinary growth.

As Easy as 1-2-800,000

Lairson, in collaboration with colleagues including Cantley, Lyssiotis, Edouard Mullarky of Weill Cornell and Harvard Medical School and Natasha Lucki of CALIBR, screened through a library of 800,000 small molecules using a high-throughput in vitro enzyme assay to detect inhibition of PHGDH. The group identified 408 candidates and further narrowed this list down based on cell-type specific anti-proliferative activity and by eliminating those inhibitors that broadly targeted other dehydrogenases.

With the successful identification of seven candidate inhibitors, the team sought to determine if these molecules could inhibit PHGDH in the complex cellular environment. To do so, the team used a mass spectrometry-based assay (test) to measure newly synthesized serine in a cell in the presence of the drug candidates.

One of the seven small molecules tested, named CBR-5884, was able to specifically inhibit serine synthesis by 30 percent, suggesting that the molecule specifically targeted PHGDH. The group went on to show that CBR-5884 was able to inhibit cell proliferation of breast cancer and melanoma cells lines that overexpress PHGDH.

As expected, CBR-5884 did not inhibit cancer cells that did not overexpress PHGDH, as they can import serine; however, when incubated in media lacking serine, the presence of CBR-5884 decreased growth in these cells.

The group anticipates much optimization work before this drug candidate can become an effective therapeutic. In pursuit of this goal, the researchers plan to take a medicinal chemistry approach to improve potency and metabolic stability.

 

How Cancer Stem Cells Thrive When Oxygen Is Scarce

(Image: Shutterstock)
image: Shutterstock

Working with human breast cancer cells and mice, scientists at The Johns Hopkins University say new experiments explain how certain cancer stem cells thrive in low oxygen conditions. Proliferation of such cells, which tend to resist chemotherapy and help tumors spread, are considered a major roadblock to successful cancer treatment.

The new research, suggesting that low-oxygen conditions spur growth through the same chain of biochemical events in both embryonic stem cells and breast cancer stem cells, could offer a path through that roadblock, the investigators say.

“There are still many questions left to answer but we now know that oxygen poor environments, like those often found in advanced human breast cancers serve as nurseries for the birth of cancer stem cells,” said Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Medicine and a member of the Johns Hopkins Kimmel Cancer Center. “That gives us a few more possible targets for drugs that diminish their threat in human cancer.”

A summary of the findings was published online March 21 in the Proceedings of the National Academy of Sciences.

“Aggressive cancers contain regions where the cancer cells are starved for oxygen and die off, yet patients with these tumors generally have the worst outcome. Our new findings tell us that low oxygen conditions actually encourage certain cancer stem cells to multiply through the same mechanism used by embryonic stem cells.”

All stem cells are immature cells known for their ability to multiply indefinitely and give rise to progenitor cells that mature into specific cell types that populate the body’s tissues during embryonic development. They also replenish tissues throughout the life of an organism. But stem cells found in tumors use those same attributes and twist them to maintain and enhance the survival of cancers.

Recent studies showed that low oxygen conditions increase levels of a family of proteins known as HIFs, or hypoxia-inducible factors, that turn on hundreds of genes, including one called NANOG that instructs cells to become stem cells.

Studies of embryonic stem cells revealed that NANOG protein levels can be lowered by a chemical process known as methylation, which involves putting a methyl group chemical tag on a protein’s messenger RNA (mRNA) precursor. Semenza said methylation leads to the destruction of NANOG’s mRNA so that no protein is made, which in turn causes the embryonic stem cells to abandon their stem cell state and mature into different cell types.

Zeroing in on NANOG, the scientists found that low oxygen conditions increased NANOG’s mRNA levels through the action of HIF proteins, which turned on the gene for ALKBH5, which decreased the methylation and subsequent destruction of NANOG’s mRNA. When they prevented the cells from making ALKBH5, NANOG levels and the number of cancer stem cells decreased. When the researchers manipulated the cell’s genetics to increase levels of ALKBH5 without exposing them to low oxygen, they found this also decreased methylation of NANOG mRNA and increased the numbers of breast cancer stem cells.

Finally, using live mice, the scientists injected 1,000 triple-negative breast cancer cells into their mammary fat pads, where the mouse version of breast cancer forms. Unaltered cells created tumors in all seven mice injected with such cells, but when cells missing ALKBH5 were used, they caused tumors in only 43 percent (six out of 14) of mice. “That confirmed for us that ALKBH5 helps preserve cancer stem cells and their tumor-forming abilities,” Semenza said.

How cancer stem cells thrive when oxygen is scarce    https://www.sciencedaily.com/releases/2016/03/160328100159.htm

The new research, suggesting that low-oxygen conditions spur growth through the same chain of biochemical events in both embryonic stem cells and breast cancer stem cells, could offer a path through that roadblock, the investigators say.

“There are still many questions left to answer but we now know that oxygen poor environments, like those often found in advanced human breast cancers serve as nurseries for the birth of cancer stem cells,” says Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Medicine and a member of the Johns Hopkins Kimmel Cancer Center.

Chuanzhao Zhang, Debangshu Samanta, Haiquan Lu, John W. Bullen, Huimin Zhang, Ivan Chen, Xiaoshun He, Gregg L. Semenza.
Hypoxia induces the breast cancer stem cell phenotype by HIF-dependent and ALKBH5-mediated m6A-demethylation of NANOG mRNA.
Proceedings of the National Academy of Sciences, 2016; 201602883     DOI: 10.1073/pnas.1602883113

Significance

Pluripotency factors, such as NANOG, play a critical role in the maintenance and specification of cancer stem cells, which are required for primary tumor formation and metastasis. In this study, we report that exposure of breast cancer cells to hypoxia (i.e., reduced O2 availability), which is a critical feature of the tumor microenvironment, induces N6-methyladenosine (m6A) demethylation and stabilization of NANOG mRNA, thereby promoting the breast cancer stem cell (BCSC) phenotype. We show that inhibiting the expression of AlkB homolog 5 (ALKBH5), which demethylates m6A, or the hypoxia-inducible factors (HIFs) HIF-1α and HIF-2α, which activate ALKBH5 gene transcription in hypoxic breast cancer cells, is an effective strategy to decrease NANOG expression and target BCSCs in vivo.

N6-methyladenosine (m6A) modification of mRNA plays a role in regulating embryonic stem cell pluripotency. However, the physiological signals that determine the balance between methylation and demethylation have not been described, nor have studies addressed the role of m6A in cancer stem cells. We report that exposure of breast cancer cells to hypoxia stimulated hypoxia-inducible factor (HIF)-1α- and HIF-2α–dependent expression of AlkB homolog 5 (ALKBH5), an m6A demethylase, which demethylated NANOG mRNA, which encodes a pluripotency factor, at an m6A residue in the 3′-UTR. Increased NANOG mRNA and protein expression, and the breast cancer stem cell (BCSC) phenotype, were induced by hypoxia in an HIF- and ALKBH5-dependent manner. Insertion of the NANOG 3′-UTR into a luciferase reporter gene led to regulation of luciferase activity by O2, HIFs, and ALKBH5, which was lost upon mutation of the methylated residue. ALKBH5 overexpression decreased NANOG mRNA methylation, increased NANOG levels, and increased the percentage of BCSCs, phenocopying the effect of hypoxia. Knockdown of ALKBH5 expression in MDA-MB-231 human breast cancer cells significantly reduced their capacity for tumor initiation as a result of reduced numbers of BCSCs. Thus, HIF-dependent ALKBH5 expression mediates enrichment of BCSCs in the hypoxic tumor microenvironment.

Specific Proteins Found to Jump Start Spread of Cancer Cells

http://www.genengnews.com/gen-news-highlights/specific-proteins-found-to-jump-start-spread-of-cancer-cells/81252417/

Metastatic breast cancer cells. [National Cancer Institute]
http://www.genengnews.com/Media/images/GENHighlight/thumb_Feb29_2016_NCI_MetastaticBreastCancerCells1797514764.jpg

Scientists at the University of California, San Diego School of Medicine and Moores Cancer Center, with colleagues in Spain and Germany, have discovered how elevated levels of particular proteins in cancer cells trigger hyperactivity in other proteins, fueling the growth and spread of a variety of cancers. Their study (“Prognostic Impact of Modulators of G Proteins in Circulating Tumor Cells from Patients with Metastatic Colorectal Cancer”) is published in Scientific Reports.

Specifically, the international team, led by senior author Pradipta Ghosh, M.D., associate professor at the University of California San Diego School of Medicine, found that increased levels of expression of some members of a protein family called guanine nucleotide exchange factors (GEFs) triggered unsuspected hyperactivation of G proteins and subsequent progression or metastasis of cancer.

The discovery suggests GEFs offer a new and more precise indicator of disease state and prognosis. “We found that elevated expression of each GEF is associated with a shorter, progression-free survival in patients with metastatic colorectal cancer,” said Dr. Ghosh. “The GEFs fared better as prognostic markers than two well-known markers of cancer progression, and the clustering of all GEFs together improved the predictive accuracy of each individual family member.”

In recent years, circulating tumor cells (CTCs), which are shed from primary tumors into the bloodstream and act as seeds for new tumors taking root in other parts of the body, have become a prognostic and predictive biomarker. The presence of CTCs is used to monitor the efficacy of therapies and detect early signs of metastasis.

But counting CTCs in the bloodstream has limited utility, said Dr. Ghosh. “Enumeration alone does not capture the particular characteristics of CTCs that are actually tumorigenic and most likely to cause additional malignancies.”

Numerous efforts are underway to improve the value and precision of CTC analysis. According to Dr. Ghosh the new findings are a step in that direction. First, GEFs activate trimeric G proteins, and second, G protein signaling is involved in CTCs. G proteins are ubiquitous and essential molecular switches involved in transmitting external signals from stimuli into cells’ interiors. They have been a subject of heightened scientific interest for many years.

Dr. Ghosh and colleagues found that elevated expression of nonreceptor GEFs activates Gαi proteins, fueling CTCs and ultimately impacting the disease course and survival of cancer patients.

“Our work shows the prognostic impact of elevated expression of individual and clustered GEFs on survival and the benefit of transcriptome analysis of G protein regulatory proteins in cancer biology,” said Dr. Ghosh. “The next step will be to carry this technology into the clinic where it can be applied directly to deciphering a patient’s state of cancer and how best to treat.”

Metastasis-on-a-Chip’ Models Cancer’s Spread

http://www.mdtmag.com/news/2016/03/metastasis-chip-models-cancers-spread?et_cid=5200644&et_rid=461755519

In the journal Biotechnology Bioengineering, the team reports on its “metastasis-on-a-chip” system believed to be one of the first laboratory models of cancer spreading from one 3D tissue to another.

The current version of the system models a colorectal tumor spreading from the colon to the liver, the most common site of metastasis. Skardal said future versions could include additional organs, such as the lung and bone marrow, which are also potential sites of metastasis. The team also plans to model other types of cancer, such as the deadly brain tumor glioblastoma

To create the system, researchers encapsulated human intestine and colorectal cancer cells inside a biocompatible gel-like material to make a mini-organ. A mini-liver composed of human liver cells was made in the same way. These organoids were placed in a “chip” system made up of a set of micro-channels and chambers etched into the chip’s surface to mimic a simplified version of the body’s circulatory system. The tumor cells were tagged with fluorescent molecules so their activity could be viewed under a microscope.

To test whether the system could model metastasis, the researchers first used highly aggressive cancer cells in the colon organoid. Under the microscope, they saw the tumor grow in the colon organoid until the cells broke free, entered the circulatory system and then invaded the liver tissue, where another tumor formed and grew. When a less aggressive form of colon cancer was used in the system, the tumor did not metastasize, but continued to grow in the colon.

To test the system’s potential for screening drugs, the team introduced Marimastat, a drug used to inhibit metastasis in human patients, into the system and found that it significantly prevented the migration of metastatic cells over a 10-day period. Likewise, the team also tested 5-fluorouracil, a common colorectal cancer drug, which reduced the metabolic activity of the tumor cells.

“We are currently exploring whether other established anti-cancer drugs have the same effects in the system as they do in patients,” said Skardal. “If this link can be validated and expanded, we believe the system can be used to screen drug candidates for patients as a tool in personalized medicine. If we can create the same model systems, only with tumor cells from an actual patient, then we believe we can use this platform to determine the best therapy for any individual patient.”

The scientists are currently working to refine their system. They plan to use 3D printing to create organoids more similar in function to natural organs. And they aim to make the process of metastasis more realistic. When cancer spreads in the human body, the tumor cells must break through blood vessels to enter the blood steam and reach other organs. The scientists plan to add a barrier of endothelial cells, the cells that line blood vessels, to the model.

This concept of modeling the body’s processes on a miniature level is made possible because of advances in micro-tissue engineering and micro-fluidics technologies. It is similar to advances in the electronics industry made possible by miniaturizing electronics on a chip.

Scientists Synthesize Anti-Cancer Agent

A schematic shows a trioxacarcin C molecule, whose structure was revealed for the first time through a new process developed by the Rice lab of synthetic organic chemist K.C. Nicolaou. Trioxacarcins are found in bacteria but synthetic versions are needed to study them for their potential as medications. Trioxacarcins have anti-cancer properties. Source: Nicolaou Group/Rice University
A schematic shows a trioxacarcin C molecule, whose structure was revealed for the first time through a new process developed by the Rice lab of synthetic organic chemist K.C. Nicolaou. Trioxacarcins are found in bacteria but synthetic versions are needed to study them for their potential as medications. Trioxacarcins have anti-cancer properties. Source: Nicolaou Group/Rice University  http://www.dddmag.com/sites/dddmag.com/files/ddd1603_rice-anticancer.jpg

A team led by Rice University synthetic organic chemist K.C. Nicolaou has developed a new process for the synthesis of a series of potent anti-cancer agents originally found in bacteria.

The Nicolaou lab finds ways to replicate rare, naturally occurring compounds in larger amounts so they can be studied by biologists and clinicians as potential new medications. It also seeks to fine-tune the molecular structures of these compounds through analog design and synthesis to improve their disease-fighting properties and lessen their side effects.

Such is the case with their synthesis of trioxacarcins, reported this month in the Journal of the American Chemical Society.

“Not only does this synthesis render these valuable molecules readily available for biological investigation, but it also allows the previously unknown full structural elucidation of one of them,” Nicolaou said. “The newly developed synthetic technologies will allow us to construct variations for biological evaluation as part of a program to optimize their pharmacological profiles.”

At present, there are no drugs based on trioxacarcins, which damage DNA through a novel mechanism, Nicolaou said.

Trioxacarcins were discovered in the fermentation broth of the bacterial strain Streptomyces bottropensis. They disrupt the replication of cancer cells by binding and chemically modifying their genetic material.

“These molecules are endowed with powerful anti-tumor properties,” Nicolaou said. “They are not as potent as shishijimicin, which we also synthesized recently, but they are more powerful than taxol, the widely used anti-cancer drug. Our objective is to make it more powerful through fine-tuning its structure.”

He said his lab is working with a biotechnology partner to pair these cytotoxic compounds (called payloads) to cancer cell-targeting antibodies through chemical linkers. The process produces so-called antibody-drug conjugates as drugs to treat cancer patients. “It’s one of the latest frontiers in personalized targeting chemotherapies,” said Nicolaou, who earlier this year won the prestigious Wolf Prize in Chemistry.

Fluorescent Nanoparticle Tracks Cancer Treatment’s Effectiveness in Hours

Bevin Fletcher, Associate Editor    http://www.biosciencetechnology.com/news/2016/03/fluorescent-nanoparticle-tracks-cancer-treatments-effectiveness-hours

Using reporter nanoparticles loaded with either a chemotherapy or immunotherapy, researchers could distinguish between drug-sensitive and drug-resistant tumors in a pre-clinical model of prostate cancer. (Source: Brigham and Women's Hospital)

Using reporter nanoparticles loaded with either a chemotherapy or immunotherapy, researchers could distinguish between drug-sensitive and drug-resistant tumors in a pre-clinical model of prostate cancer. (Source: Brigham and Women’s Hospital)

Bioengineers at Brigham and Women’s Hospital have developed a new technique to help determine if chemotherapy is working in as few as eight hours after treatment. The new approach, which can also be used for monitoring the effectiveness of immunotherapy, has shown success in pre-clinical models.

The technology utilizes a nanoparticle, carrying anti-cancer drugs, that glows green when cancer cells begin dying. Researchers, using  the “reporter nanoparticles” that responds to a particular enzyme known as caspase, which is activated when cells die, were able to distinguish between a tumor that is drug-sensitive or drug-resistant much faster than conventional detection methods such as PET scans, CT and MRI.  The findings were published online March 28 in the Proceedings of the National Academy of Sciences.

“Using this approach, the cells light up the moment a cancer drug starts working,” co-corresponding author Shiladitya Sengupta, Ph.D., principal investigator in BWH’s Division of Bioengineering, said in a prepared statement.  “We can determine if a cancer therapy is effective within hours of treatment.  Our long-term goal is to find a way to monitor outcomes very early so that we don’t give a chemotherapy drug to patients who are not responding to it.”

Cancer killers send signal of success

Nanoparticles deliver drug, then give real-time feedback when tumor cells die   BY   SARAH SCHWARTZ

New lab-made nanoparticles deliver cancer drugs into tumors, then report their effects in real time by lighting up in response to proteins produced by dying cells. More light (right, green) indicates a tumor is responding to chemotherapy.

Tiny biochemical bundles carry chemotherapy drugs into tumors and light up when surrounding cancer cells start dying. Future iterations of these lab-made particles could allow doctors to monitor the effects of cancer treatment in real time, researchers report the week of March 28 in theProceedings of the National Academy of Sciences.

“This is the first system that allows you to read out whether your drug is working or not,” says study coauthor Shiladitya Sengupta, a bioengineer at Brigham and Women’s Hospital in Boston.

Each roughly 100-nanometer-wide particle consists of a drug and a fluorescent dye linked to a coiled molecular chain. Before the particles enter cells, the dye is tethered to a “quencher” molecule that prevents it from lighting up. When injected into the bloodstream of a mouse with cancer, the nanoparticles accumulate in tumor cells and release the drug, which activates a protein that tears a cancer cell apart. This cell-splitting protein not only kills the tumor cell, but also severs the link between the dye and the quencher, allowing the nanoparticles to glow under infrared light.

Reporter nanoparticle that monitors its anticancer efficacy in real time

Ashish Kulkarnia,b,1,Poornima Raoa,b,Siva Natarajana,b,Aaron Goldman, et al.
http://www.pnas.org/content/early/2016/03/28/1603455113.abstract

The ability to identify responders and nonresponders very early during chemotherapy by direct visualization of the activity of the anticancer treatment and to switch, if necessary, to a regimen that is effective can have a significant effect on the outcome as well as quality of life. Current approaches to quantify response rely on imaging techniques that fail to detect very early responses. In the case of immunotherapy, the early anatomical readout is often discordant with the biological response. This study describes a self-reporting nanomedicine that not only delivers chemotherapy or immunotherapy to the tumor but also reports back on its efficacy in real time, thereby identifying responders and nonresponders early on

The ability to monitor the efficacy of an anticancer treatment in real time can have a critical effect on the outcome. Currently, clinical readouts of efficacy rely on indirect or anatomic measurements, which occur over prolonged time scales postchemotherapy or postimmunotherapy and may not be concordant with the actual effect. Here we describe the biology-inspired engineering of a simple 2-in-1 reporter nanoparticle that not only delivers a cytotoxic or an immunotherapy payload to the tumor but also reports back on the efficacy in real time. The reporter nanoparticles are engineered from a novel two-staged stimuli-responsive polymeric material with an optimal ratio of an enzyme-cleavable drug or immunotherapy (effector elements) and a drug function-activatable reporter element. The spatiotemporally constrained delivery of the effector and the reporter elements in a single nanoparticle produces maximum signal enhancement due to the availability of the reporter element in the same cell as the drug, thereby effectively capturing the temporal apoptosis process. Using chemotherapy-sensitive and chemotherapy-resistant tumors in vivo, we show that the reporter nanoparticles can provide a real-time noninvasive readout of tumor response to chemotherapy. The reporter nanoparticle can also monitor the efficacy of immune checkpoint inhibition in melanoma. The self-reporting capability, for the first time to our knowledge, captures an anticancer nanoparticle in action in vivo.

 

Cancer Treatment’s New Direction  
Genetic testing helps oncologists target tumors and tailor treatments
http://www.wsj.com/articles/cancer-treatments-new-direction-1459193085

Evan Johnson had battled a cold for weeks, endured occasional nosebleeds and felt so fatigued he struggled to finish his workouts at the gym. But it was the unexplained bruises and chest pain that ultimately sent the then 23-year-old senior at the University of North Dakota to the Mayo Clinic. There a genetic test revealed a particularly aggressive form of acute myeloid leukemia. That was two years ago.

The harrowing roller-coaster that followed for Mr. Johnson and his family highlights new directions oncologists are taking with genetic testing to find and attack cancer. Tumors can evolve to resist treatments, and doctors are beginning to turn such setbacks into possible advantages by identifying new targets to attack as the tumors change.

His course involved a failed stem cell transplant, a half-dozen different drug regimens, four relapses and life-threatening side effects related to his treatment.

Nine months in, his leukemia had evolved to develop a surprising new mutation. The change meant the cancer escaped one treatment, but the new anomaly provided doctors with a fresh target, one susceptible to drugs approved for other cancers. Doctors adjusted Mr. Johnson’s treatment accordingly, knocked out the disease and paved the way for a second, more successful stem cell transplant. He has now been free of leukemia for a year.

Now patients with advanced cancer who are treated at major centers can expect to have their tumors sequenced, in hopes of finding a match in a growing medicine chest of drugs that precisely target mutations that drive cancer’s growth. When they work, such matches can have a dramatic effect on tumors. But these “precision medicines” aren’t cures. They are often foiled when tumors evolve, pushing doctors to take the next step to identify new mutations in hopes of attacking them with an effective treatment.

Dr. Kasi and his Mayo colleagues—Naseema Gangat, a hematologist, and Shahrukh Hashmi, a transplant specialist—are among the authors of an account of Mr. Johnson’s case published in January in the journal Leukemia Research Reports.

Before qualifying for a transplant, a patient’s blasts need to be under 5%.

To get under 5%, he started on a standard chemotherapy regimen and almost immediately, things went south. His blast cells plummeted, but “the chemo just wiped out my immune system,”

Then as mysteriously as it began, a serious mycotic throat infection stopped. But Mr. Johnson couldn’t tolerate the chemo, and his blast cells were on the rise. A two-drug combination that included the liver cancer drug Nexavar, which targets the FLT3 mutation, knocked back the blast cells. But the stem cell transplant in May, which came from one of his brothers, failed to take, and he relapsed after 67 days, around late July.

He was put into a clinical trial of an experimental AML drug being developed by Astellas Pharma of Japan. He started to regain weight. In November 2014, doctors spotted the initial signs in blood tests that Mr. Johnson’s cancer was evolving to acquire a new mutation. By late January, he relapsed again , but there was a Philadelphia chromosome mutation,  a well-known genetic alteration associated with chronic myeloid leukemia. It also is a target of the blockbuster cancer drug Gleevec and several other medicines.

Clonal evolution of AML on novel FMS-like tyrosine kinase-3 (FLT3) inhibitor therapy with evolving actionable targets

Naseema GangatMark R. LitzowMrinal M. PatnaikShahrukh K. HashmiNaseema Gangat

Highlights
•   The article reports on a case of AML that underwent clonal evolution.
•   We report on novel acquisition of the Philadelphia t(9;22) translocation in AML.
•   Next generation sequencing maybe helpful in these refractory/relapse cases.
•   Novel FLT3-inhibitor targeted therapies are another option in patients with AML.
•   Personalizing cancer treatment based on evolving targets is a viable option.

For acute myeloid leukemia (AML), identification of activating mutations in the FMS-like tyrosine kinase-3 (FLT3) has led to the development of several FLT3-inhibitors. Here we present clinical and next generation sequencing data at the time of progression of a patient on a novel FLT3-inhibitor clinical trial (ASP2215) to show that employing therapeutic interventions with these novel targeted therapies can lead to consequences secondary to selective pressure and clonal evolution of cancer. We describe novel findings alongside data on treatment directed towards actionable aberrations acquired during the process. (Clinical Trial: NCT02014558; registered at: 〈https://clinicaltrials.gov/ct2/show/NCT02014558〉)

The development of kinase inhibitors for the treatment of leukemia has revolutionized the care of these patients. Since the introduction of imatinib for the treatment of chronic myeloid leukemia, multiple other tyrosine kinase inhibitors (TKIs) have become available[1]. Additionally, for acute myeloid leukemia (AML), identification of activating mutations in the FMS-like tyrosine kinase-3 (FLT3) has led to the development of several FLT3-inhibitors [2], [3], [4] and [5]. The article herein reports a unique case of AML that underwent clonal evolution while on a novel FLT3-inhibitor clinical trial.

Our work herein presents clinical and next generation sequencing data at the time of progression to illustrate these important concepts stemming from Darwinian evolution [6]. We describe novel findings alongside data on treatment directed towards actionable aberrations acquired during the process.

Our work focuses on a 23-year-old male who presented with 3 months history of fatigue and easy bruising, a white blood count of 22.0×109/L with 51% circulating blasts, hemoglobin 7.6 g/dL, and a platelet count of 43×109/L. A bone marrow biopsy confirmed a diagnosis of AML. Initial cytogenetic studies identified trisomy 8 in all the twenty metaphases examined. Mutational analysis revealed an internal tandem duplication of the FLT3 gene (FLT3-ITD).

He received standard induction chemotherapy (7+3) with cytarabine (ARA-C; 100 mg/m2for 7 days) and daunorubicin (DNM; 60 mg/m2 for 3 days). His induction chemotherapy was complicated by severe palatine and uvular necrosis of indeterminate etiology (possible mucormycosis).

Bone marrow biopsy at day 28 demonstrated persistent disease with 10% bone marrow blasts (Fig. 1). Due to his complicated clinical course and the presence of a FLT3-ITD, salvage therapy with 5-azacitidine (5-AZA) and sorafenib (SFN) was instituted. Table 1.
The highlighted therapies were employed in this particular case at various time points as shown in Fig. 1.

http://ars.els-cdn.com/content/image/1-s2.0-S221304891530025X-gr1.jpg

References

    • [1]
    • J.E. Cortes, D.W. Kim, J. Pinilla-Ibarz, et al.
    • A phase 2 trial of ponatinib in Philadelphia chromosome-positive leukemias
    • New Engl. J. Med., 369 (19) (2013), pp. 1783–1796
    • [2]
    • F. Ravandi, M.L. Alattar, M.R. Grunwald, et al.
    • Phase 2 study of azacytidine plus sorafenib in patients with acute myeloid leukemia and FLT-3 internal tandem duplication mutation
    • Blood, 121 (23) (2013), pp. 4655–4662
    • [3]
    • N.P. Shah, M. Talpaz, M.W. Deininger, et al.
    • Ponatinib in patients with refractory acute myeloid leukaemia: findings from a phase 1 study
    • Br. J. Haematol., 162 (4) (2013), pp. 548–552
    • [4]
    • Y. Alvarado, H.M. Kantarjian, R. Luthra, et al.
    • Treatment with FLT3 inhibitor in patients with FLT3-mutated acute myeloid leukemia is associated with development of secondary FLT3-tyrosine kinase domain mutations
    • Cancer, 120 (14) (2014), pp. 2142–2149
    • [5]
    • C.C. Smith, C. Zhang, K.C. Lin, et al.
    • Characterizing and overriding the structural mechanism of the Quizartinib-Resistant FLT3 “Gatekeeper” F691L mutation with PLX3397
    • Cancer Discov. (2015)
    • [6]
    • M. Greaves, C.C. Maley
    • Clonal evolution in cancer
    • Nature, 481 (7381) (2012), pp. 306–313

 

 

 

Read Full Post »

Older Posts »