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Archive for the ‘hNPCs’ Category


Writer and curator: Larry H. Bernstein, MD, FCAP and
Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013-01-23/larryhbern/Regulation-of-somatic-stem-cell-function/

There is an explosion of work-in-progress in applications to regenerative medicine using inducible pluripotent stem cells in both endothelial and cardiomyocyte postischemic repair, and also in post bone marrow radiation restoration, with benefits and hazards.  The following article is quite novel in that it deals with stem cell regulation by DNA methylation.  Therefore, it deals with the essentiality of methylation of DNA in epigenetic regulation.

This is the fourth discussion of a several part series leading from the genome, to protein synthesis (1), posttranslational modification of proteins (2), examples of protein effects on metabolism and signaling pathways (3), and leading to disruption of signaling pathways in disease (4), and effects leading to mutagenesis.

1.  A Primer on DNAand DNA Replication

2.  Overview of translational medicine

3.  Genes, proteomes, and their interaction

4. Regulation of somatic stem cell Function

5.  Proteomics – The Pathway to Understanding and Decision-making in Medicine

6.  Genomics, Proteomics and standards

7.  Long Non-coding RNAs Can Encode Proteins After All

8.  Proteins and cellular adaptation to stress

9.  Loss of normal growth regulation

 

Posttranslational modification is a step in protein biosynthesis. Proteins are created by ribosomes translating mRNA into polypeptide chains. These polypeptide chains undergo
PTM before becoming the mature protein product.

Regulation of somatic stem cell Function by DNA Methylation and Genomic Imprinting

Mo Li1, Na Young Kim1, Shigeo Masuda1 and Juan Carlos izpisua Belmonte1,2 1Salk institute for Biological Studies, 10010 N Torrey Pines Rd, La Jolla, CA 92037, USA. 2Center of Regenerative Medicine in Barcelona, Dr Aiguader, 88, 08003 Barcelona, Spain. Corresponding author email: mli@salk.edu

Cell & Tissue Transplantation & Therapy 2013:5 19–23
http://dx.doi.org/10.4137/CTTT.S12142
This article is available from http://www.la-press.com

Abstract:

Epigenetic regulation is essential for self-renewal and differentiation of somatic stem cells, including

  • hematopoietic stem cells (HSCs) and
  • neural stem cells (NSCs).

The role of DNA methylation, a key epigenetic pathway,

  • in regulating somatic stem cell function
    • under physiological conditions and during aging

has been intensively investigated.

Accumulating evidence highlights the dynamic nature of

  • the DNAmethylome
    • during lineage commitment of somatic stem cells and
  • the pivotal role of DNAmethyltransferases in
    • stem cell self-renewal and differentiation.

Recent studies on genomic imprinting have shed light on

  • the imprinted gene network (IGN) in somatic stem cells,
  1. where a subset of imprinted genes remain expressed and
  2. are important for maintaining self-renewal of these cells.

Together with emerging technologies, elucidation of the epigenetic mechanisms regulating somatic stem cells with normal or pathological functions may contribute to the development of regenerative medicine.

Keywords: somatic stem cells, epigenetics, DNA methylation, genomic imprinting, hematopoietic stem cells, neural stem cells

Introduction

In adult animals, somatic stem cells (also known as adult stem cells) are responsible for maintaining tissue homeostasis and participate in tissue regeneration under injury conditions. Self-renewal and differentiation are two important aspects of somatic stem cell function. Epigenetic mechanisms underlying these processes have been intensively investigated. With the increasing ability

  • to identify and manipulate somatic stem cell populations from diverse tissues,
  • it is possible to dissect the epigenetic pathways that are
  1. either unique for a specific tissue or
  2. universally important in regulating stemness and differentiation.

Epigenetic control of somatic stem cell function exists at various levels, including

  • DNA methylation,
  • histone modification, and
  • higher-order chromatin structure dynamics.

Here, we focus on recent progress in our understanding of how

  • DNA methylation regulates somatic stem cell function.

DNA Methylation and stem cell Function

The role of DNA methylation in somatic stem cell compartments has gained increasing attention. Recent  evidence has shown that

  • DNA methylation is dynamically regulated during somatic stem cell differentiation and aging.1

A study of methylomes of human hematopoietic stem cells (HSCs) and two mature hematopoietic lineages,

  • including B cells and neutrophils, showed that
    • hypomethylated regions of lineage-specific genes often become methylated in opposing lineages, and that
    • progenitors display an intermediate methylation pattern

that is poised for lineage-specific resolution.2

Another study compared genome-wide promoter DNA methylation in human cord blood hematopoietic progenitor cells (HPCs) with

  • that in mobilized peripheral blood HPCs from aged individuals.

It was found that aged HPCs lose DNA methylation in a subset of genes that are hypomethylated in differentiated myeloid cells and

  • gain de novo DNA methylation at polycomb repressive complex 2 (PRC2) target sites.3

It was hypothesized that such epigenetic changes contribute to age-related loss of HSC function, such as a bias toward myeloid lineages. Recently, Beerman et al. studied the global DNA methylation landscape of HSCs in the context of

  • age-associated decline of HSC function.4

Over- all, the DNA methylation landscape remains stable during HSC ontogeny. However, HSCs isolated from old mice display higher global DNA methylation. Interestingly, they observed

  • localized DNA methylation changes in genomic regions associated with hematopoietic lineage differentiation.

These methylation changes preferentially map to genes

  • that are expressed in downstream progenitor and effector cells.

For example, genes that are important for the lymphoid and erythroid lineages

  • become methylated in “old” HSCs,

which is consistent with

  • the decline of lymphopoiesis and erythropoiesis during aging.

Additionally, inducing HSC proliferation by 5-fluorouracil treatment or

  • by limiting the number of transplantedHSCs
    • recapitulates the functional decline and DNA methylation changes during physiological aging.

A closer examination of the overlapping genes with significant DNA methylation changes during aging or enforced proliferation showed

  • an enrichment of DNA hypermethylation at PRC2 target loci,

echoing the observation by Bocker et al. in human HSCs.

Interestingly, a recent report showed that epigenetic alterations such as DNA hypermethylation that are accrued during aging,

  • can be fully reset by somatic reprogramming,

raising an interesting possibility that these aging-related epigenetic defects may be reserved by small molecules.5

Methylation of cytosines at CpG dinucleotides is catalyzed by three key enzymes.

DNA (cytosine-5)- methyltransferase 1 (DNMT1) is responsible for maintaining DNA methylation patterns during DNA replication

  • by methylating the newly synthesized hemi-methylated DNA.

The other two DNA methyltransferases, DNMT3a and DNMT3b,

  • are not DNA replication-dependent and can methylate fully unmethylated DNA de novo.

They are responsible for establishing new DNA methylation patterns during development.

DNMT3a, a gene required for neurogenesis,

  • is expressed in postnatal neural stem cells (NSCs).

In NSCs, DNMT3a methylates non-proximal promoter regions, such as gene bodies and intergenic regions. Surprisingly, rather than silencing gene expression,

DNMT3a-mediated DNA methylation in gene bodies antagonizes Polycomb-dependent repression and

  • facilitates the expression of neurogenic genes.6

The role of DNMT3a in HSCs has also been investigated. Both Dnmt3a and Dnmt3b are expressed in HSCs. An earlier study did not identify any defects in HSC function when Dnmt3a or Dnmt3b was removed.  However,

  • HSCs lackingboth of these de novomethyltransferases
    • fail to self-renew, yet retain the capacity to differentiate.7

A more recent study re-examined

  • the consequences of Dnmt3a loss in HSCs and
  • uncovered a progressive defect in differentiation that is only manifested during serial transplantation.8

At the molecular level, while Dnmt3a loss results in the expected hypomethylation at some loci,

  • it counterintuitively causes hypermethylation in even more regions.8

This seemingly paradoxical result echoes the  unconventional role of Dnmt3a in transcriptional  activation in NSCs (as discussed above). Both cases suggest a more complex regulatory function of DNMT3a that is

  • beyond simply methylating DNA.

In contrast, the loss of Dnmt1 produces more dramatic and immediate phenotypes in HSCs, manifested

  • in premature HSC exhaustion and
  • block of lymphoid differentiation,

highlighting the distinct requirements for different DNA methyltransferases in HSCs.9,10

Genomic Imprinting and stemness

DNA methylation also underlies genomic imprinting, which is an

  • evolutionarily conserved epigenetic mechanism of ensuring appropriate gene dosage during development.

One allele of the imprinted genes is

  • epigenetically marked by DNA methylation to be silenced according to the parental origin.

The pattern of imprinting

  • is established in germ cells and maintained in somatic cells.

Imprinted genes are thought to play critical roles in organismal growth and are relatively downregulated after birth.11 Recently, a series of reports demonstrated that

  • a subset of imprinted genes belonging to the purported imprinted gene network (IGN)12
  • remain expressed in somatic stem cells and
  • are important for maintaining self-renewal of these cells.

Through gene expression profiling, one group identified that several members of the IGN are expressed in

  1. murine muscle,
  2. epidermal, and
  3. long-term hematopoietic stem cells
  4. as well as in human epidermal and hematopoietic stem cells.13

In particular, the paternally expressed gene 3 (Peg3) gene was shown by another group

  • to mark cycling and quiescent stem cells in a wide variety of mouse tissues.14

The role of imprinted genes in regulating somatic stem cell function has been examined in two types of tissues.

In bronchioalveolar stem cells (BASCs), a lung epithelial stem cell population,

  • expression of IGN members is required for their self-renewal.

Bmi1, a polycomb repressive  complex 1 (PRC1) subunit,

  • is essential for controlling the expression of imprinted genes in BASCs without affecting their imprinting status.15

In Bmi1 mutant BASCs,  many members of the IGN become derepressed,

  • including p57, H19, Dlk1, Peg3, Ndn, Mest, Gtl2, Grb10, Plagl1, and Igf2.

Knockdown of p57, which is the most differentially expressed imprinted gene between normal and mutant BASCs,

  • partially rescues the self-renewal defect of lung stem cells.

Interestingly, insufficient levels of p57 also inhibit self-renewal of lung stem cells. Because p57 expression

  • remains monoallelic in Bmi1 knockdown cells,
  • Bmi1 is thought to maintain an appropriate level of expression from the expressed allele of p57.15

Another IGN member- delta-like homologue 1 (Dlk1) has been shown to be important for postnatal neurogenesis. Interestingly, in this context,

  • Dlk1 loses its imprinting in postnatal neural stem cells and niche astrocytes.16

These studies suggest that modulating IGN may represent another

  • epigenetic mechanism for balancing self-renewal and differentiation in somatic stem cells.

Thus, somatic stem cells either co-opt or remodel these developmental pathways involving the IGN

  • to fulfill the needs of tissue homeostasis during the adult stage.

In summary, several factors participate in regulating the epigenome of somatic stem cells.

Perturbations in the epigenome of somatic stem cells,

  • either during organismal aging or under pathological conditions,

will tip the balance between self-renewal and differentiation of somatic stem cells (Fig. 1). A detailed understanding of the mechanisms underlying these changes will likely result in novel therapeutic approaches targeting somatic stem cells.

Figure 1. The epigenome of somatic stem cells is regulated by diverse factors.

Future perspectives The epigenetic mechanisms governing self-renewal and differentiation of somatic stem cells are likely to be complex because of the diverse needs of different tissues. It would be interesting to determine whether a common mechanism, such as the IGN, exists across different somatic stem cells. Additionally, study- ing epigenetic pathways that are specific to one type of somatic stem cell requires the isolation of these cells and their differentiated progeny, which is more practical in model organisms than in humans. Along these lines, developing robust in vitro culture methods for human somatic stem cells and protocols for differentiating these cells into specific lineages are critical for uncovering epigenetic pathways that are unique to human somatic stem cells. In recent years, the field has seen a great improvement in methods of directed differentiation of human embryonic stem cells and induced pluripotent stem cells (iPSCs). For example, it is relatively straightforward to produce high-purity cell populations that resemble neural stem cells or mesenchymal stem cells from iPSCs.17

These methodologies not only are useful for studying the normal function of somatic stem cells, but also provide an exciting opportunity for understanding the role of somatic stem cells in disease pathology and a platform to screen for drugs. A recent study under- scored the usefulness of this approach. Liu et al. studied neural stem cells derived from Parkinson’s disease human iPSCs and uncovered previously unknown defects in nuclear morphology and epigenetic regulation in these derived NSCs.18 The cellular defects only menifest in “aged” neural stem cells, which is consistent with the fact that Parkinson’s disease pri- marily manifests in old age. More  importantly, this study identified neural stem cell as a potential target of therapeutic intervention for Parkinson’s disease.

Targeted modification of the human genome is  another technological advancement that is on the horizon to greatly facilitate the dissection of epige- netic pathways in somatic stem cells. Although gene targeting in somatic stem cells has been historically challenging, there have been encouraging successful reports following development of new genome-e diting technologies, such as Helper-dependent adenovi- ral vectors, TALENs, and CAS9/CRISPR. With the development of these new technologies, it seems that the stage has been set for a new wave of discoveries in epigenetic mechanisms of somatic stem cells.

References

1. Li M, Liu GH, Izpisua Belmonte JC. Navigating the epigenetic landscape of pluripotent stem cells. Nat Rev Mol Cell Biol. 2012;13(8):524–535.

2. Hodges E, Molaro A, Dos Santos CO, et al. Directional DNA methylation changes and complex intermediate states accompany lineage specificity in the adult hematopoietic compartment. Mol Cell. 2011;44(1):17–28.

3. Bocker MT, Hellwig I, Breiling A, Eckstein V, Ho AD, Lyko F. Genome- wide promoter DNA methylation dynamics of human hematopoietic progen- itor cells during differentiation and aging. Blood. 2011;117(19):e182–e189.

4. Beerman I, Bock C, Garrison BS, et al. Proliferation-dependent alterations of the DNA methylation landscape underlie hematopoietic stem cell aging. Cell Stem Cell. 2013;12(4):413–425.

5. Wahlestedt M, Norddahl GL, Sten G, et al. An epigenetic component of hematopoietic stem cell aging amenable to reprogramming into a young state. Blood. 2013;121(21):4257–4264.

6. Wu H, Coskun V, Tao J, et al. Dnmt3a-dependent nonpromoter DNA methylation facilitates transcription of neurogenic genes. Science. 2010; 329(5990):444–448.

7. Tadokoro Y, Ema H, Okano M, Li E, Nakauchi H. De novo DNA meth- yltransferase is essential for self-renewal, but not for differentiation, in hematopoietic stem cells. J Exp Med. 2007;204(4):715–722.

8. Challen GA, Sun D, Jeong M, et al. Dnmt3a is essential for hematopoietic stem cell differentiation. Nat Genet. 2011;44(1):23–31.

9. Broske AM, Vockentanz L, Kharazi S, et al. DNA methylation protects hematopoietic stem cell multipotency from myeloerythroid restriction. Nat Genet. 2009;41(11):1207–1215.

10. Trowbridge JJ, Snow JW, Kim J, Orkin SH. DNA methyltransferase 1 is essential for and uniquely regulates hematopoietic stem and progenitor cells. Cell Stem Cell. 2009;5(4):442–449.

11. Wood AJ, Oakey RJ. Genomic imprinting in mammals: emerging themes and established theories. PLoS Genet. 2006;2(11):e147.

12. Lui JC, Finkielstain GP, Barnes KM, Baron J. An imprinted gene network that controls mammalian somatic growth is down-regulated during postna- tal growth deceleration in multiple organs. Am J Physiol Regul Integr Comp Physiol. 2008;295(1):R189–R196.

13. Berg JS, Lin KK, Sonnet C, et al. Imprinted genes that regulate early mam- malian growth are coexpressed in somatic stem cells. PLoS One. 2011; 6(10):e26410.

14. Besson V, Smeriglio P, Wegener A, et al. PW1 gene/paternally expressed gene 3 (PW1/Peg3) identifies multiple adult stem and progenitor cell popu- lations. Proc Natl Acad Sci U S A. 2011;108(28):11470–11475.

15. Zacharek SJ, Fillmore CM, Lau AN, et al. Lung stem cell self-renewal relies on BMI1-dependent control of expression at imprinted loci. Cell Stem Cell. 2011;9(3):272–281.

16. Ferron SR, Charalambous M, Radford E, et al. Postnatal loss of Dlk1 imprinting in stem cells and niche astrocytes regulates neurogenesis. Nature. 2011;475(7356):381–385.

17. Li W, Sun W, Zhang Y, et al. Rapid induction and long-term self-renewal of primitive neural precursors from human embryonic stem cells by small molecule inhibitors. Proc Natl Acad Sci U S A. 2011;108(20):8299–8304.

18. Liu GH, Qu J, Suzuki K, et al. Progressive degeneration of human neural stem cells caused by pathogenic LRRK2. Nature. 2012;491(7425):603–607.

 

Additional References in Leaders in Pharmaceutical Intelligence

Proteomics and Biomarker Discovery

https://pharmaceuticalintelligence.com/2012/08/21/proteomics-and-biomarker-discovery/

Developments in the Genomics and Proteomics of Type 2 Diabetes Mellitus and Treatment Targets

https://pharmaceuticalintelligence.com/2013/12/08/developments-in-the-genomics-and-proteomics-of-type-2-diabetes-mellitus-and-treatment-targets/

Immune activation, immunity, antibacterial activity

https://pharmaceuticalintelligence.com/2014/07/06/immune-activation-immunity-antibacterial-activity/

Ubiquitin-Proteosome pathway, Autophagy, the Mitochondrion, Proteolysis and Cell Apoptosis: Part III

https://pharmaceuticalintelligence.com/2013/02/14/ubiquinin-proteosome-pathway-autophagy-the-mitochondrion-proteolysis-and-cell-apoptosis-reconsidered/

Ubiquinin-Proteosome pathway, autophagy, the mitochondrion, proteolysis and cell apoptosis

https://pharmaceuticalintelligence.com/2012/10/30/ubiquinin-proteosome-pathway-autophagy-the-mitochondrion-proteolysis-and-cell-apoptosis/

Research on inflammasomes opens therapeutic ways for treatment of rheumatoid arthritis

https://pharmaceuticalintelligence.com/2014/07/12/research-on-inflammasomes-opens-therapeutic-ways-for-treatment-of-rheumatoid-arthritis/

Update on mitochondrial function, respiration, and associated disorders

https://pharmaceuticalintelligence.com/2014/07/08/update-on-mitochondrial-function-respiration-and-associated-disorders/

MIT Scientists on Proteomics: All the Proteins in the Mitochondrial Matrix identified

https://pharmaceuticalintelligence.com/2013/02/03/mit-scientists-on-proteomics-all-the-proteins-in-the-mitochondrial-matrix-identified/

Mitochondrial Damage and Repair under Oxidative Stress

https://pharmaceuticalintelligence.com/2012/10/28/mitochondrial-damage-and-repair-under-oxidative-stress/

Bzzz! Are fruitflies like us?

https://pharmaceuticalintelligence.com/2014/07/07/bzzz-are-fruitflies-like-us/

Discovery of Imigliptin, a Novel Selective DPP-4 Inhibitor for the Treatment of Type 2 Diabetes

https://pharmaceuticalintelligence.com/2014/06/25/discovery-of-imigliptin-a-novel-selective-dpp-4-inhibitor-for-the-treatment-of-type-2-diabetes/

Molecular biology mystery unravelled

https://pharmaceuticalintelligence.com/2014/06/22/molecular-biology-mystery-unravelled/

Gene Switch Takes Blood Cells to Leukemia and Back Again

https://pharmaceuticalintelligence.com/2014/06/20/gene-switch-takes-blood-cells-to-leukemia-and-back-again/

Wound-healing role for microRNAs in colon offer new insight to inflammatory bowel diseases

https://pharmaceuticalintelligence.com/2014/06/19/wound-healing-role-for-micrornas-in-colon-offer-new-insight-to-inflammatory-bowel-diseases/

Targeting a key driver of cancer

https://pharmaceuticalintelligence.com/2014/06/20/targeting-a-key-driver-of-cancer/

Tang Prize for 2014: Immunity and Cancer

https://pharmaceuticalintelligence.com/2014/06/20/tang-prize-for-2014-immunity-and-cancer/

Confined Indolamine 2, 3 dioxygenase (IDO) Controls the Hemeostasis of Immune Responses for Good and Bad                             Demet Sag, PhD

https://pharmaceuticalintelligence.com/2013/07/31/confined-indolamine-2-3-dehydrogenase-controls-the-hemostasis-of-immune-responses-for-good-and-bad/

3:45 – 4:15, 2014, Scott Lowe “Tumor suppressor and tumor maintenance genes”

12:00 – 12:30, 6/13/2014, John Maraganore “Progress in advancement of RNAi therapeutics”

9:30 – 10:00, 6/13/2014, David Bartel “MicroRNAs, poly(A) tails and post-transcriptional gene regulation.”

10:00 – 10:30, 6/13/2014, Joshua Mendell “Novel microRNA functions in mammalian physiology and cancer”

Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2014/06/04/koch-institute-for-integrative-cancer-research-mit-summer-symposium-2014-rna-biology-cancer-and-therapeutic-implications-june-13-2014-830am-430pm-kresge-auditorium-mit/

Targeted genome editing by lentiviral protein transduction of zinc-finger and TAL-effector nucleases          Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2014/06/04/targeted-genome-editing-by-lentiviral-protein-transduction-of-zinc-finger-and-tal-effector-nucleases/

Illana Gozes discovered Novel Protein Fragments that have proven Protective Properties for Cognitive Functioning

Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2014/06/03/prof-illana-gozes-discovered-novel-protein-fragments-that-have-proven-protective-properties-for-cognitive-functioning/

 

 

 

 

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Larry H Bernstein, MD, FCAP, reporter and curator

htto://pharmaceuticalintelligence.com/2013-12-07/larryhbern/Advances-in-Stem-Cell-Research

The amount of success in stem cell research and recent successes is notable.

GEN News  Dec 5, 2013
Stem Cell Leaders Call for Human Embryome Project

Just as an international consortium was formed to map and sequence the human genome, now a group of stem cell and regenerative medicine scientists say it’s critical that such an effort be ramped up to do a similar project focused on the human embryome.

This was the key message of a panel discussion, “From Mapping the Genome to Mapping the Embryome: The Urgent Need for an International Initiative,” moderated by Michael West, Ph.D., CEO of Biotime. It took place at the World Stem Cell Summit, which is taking place this week in San Diego.

“It is becoming increasingly clear in regenerative medicine that pluripotent stem cells, embryonic stem cells, and IPs cells will be as fundamentally important to medicine as was DNA. Maybe even bigger because you can genetically engineer these cells,” said Dr. West.

Dr. West and his colleagues adamantly believe that there needs to be a large international effort aimed at mapping the cellular and molecular basis of all human life starting with the fertilized egg and working its way up to the body of the adult. This is what it is termed the embryome.

“The opportunity presented by pluripotent stem cells to manufacture for the first time in the history of medicine all of the cellular components of the human body on an industrial scale is at once both an opportunity and a challenge,” said Dr. West. “The opportunity is to build a new field we call regenerative medicine in which many currently incurable diseases are treated with cells capable of regenerating tissues afflicted with disease. The challenge relates to the complexity of the cell types in the body and our ability to manufacture products with precisely defined compositions for human clinical use.”

Dr. West went on to say that to get these different types of stem cells into the clinic, and approved by the FDA, researchers will fully need to understand all aspects of the biology of these cells. An identification and understanding of any contaminating cells will also be essential to success in this field. The question to ask is “What is in the syringe?”

Unlike recombinant DNA, continued Dr. West, the contaminants in pluripotent stem cells are alive and may make things that are undesirable at the intended point of therapy. For example, you might have a bioreactor full of cells that are making heart muscle to regenerate heart function in a patient. But you have to be careful that your cells are not contaminated with neural crest cells from the head area which could generate a tooth along with the heart muscle.

“These contaminants, if you do not remove them, can lead to years of delay in filing an IND and a runup in costs as you try to identify these cells,” explained Dr. West.

The major problem in identifying them, according to Dr. West, is that no one has ever mapped the molecular markers or even a rudimentary cell ontology tree, i.e., mapped out the tree from the fertilized egg to the cells of the human body.

“If [there were] a detailed map of all the cellular and molecular components of life from the fertilized egg to adulthood, and then databased in a manner to the information in the human genome, medicine would be the true beneficiary,” added Dr. West. “That’s why we have made this call for an international initiative.”

Also, watch our video “A Brief History of Stem Cells” to see a timeline spanning over 60 years of stem cell research.

Mary Ann Liebert Wins Stem Cell Education Award

Mary Ann Liebert, president and CEO of Mary Ann Liebert Inc., and publisher of GEN, was presented with the Stem Cell Education Award by the Genetics Policy Institute. The award was given during a ceremony at dinner which took place at the World Stem Cell Summit, which is being held in San Diego this week.

Liebert was cited for her outstanding “work in educating patients, researchers, and the broader stem cell community, and in raising the standard in medical research journalism.” Among the seventy journals the Liebert company publishes is the peer-reviewed Stem Cells and Development.

In her acceptance speech Liebert told the audience that she was extremely gratified in being so recognized and thanked the entire staff at her company for their dedication in helping to promote excellence in medical publishing.

In his introductory remarks during the award ceremony GEN’s long-time editor in chief John Sterling noted that Mary Ann always encourages her editors and writers “to inform, enlighten when they can, and educate as much as possible.”

Sterling added that while she started her company 33 years ago her vision for her publications remains the same: “to help advance our knowledge of science and medicine in the best ways possible.”

 

Neural Precursors “Cure MS” in Mice

During a session at the this week’s World Stem Cell Summit in San Diego, an international research team described an “astonishing” experiment in which a mouse model of multiple sclerosis was able to virtually totally recover and move normally after being transplanted with human neural precursor cells (hNPC). The scientists were able to show almost full recovery in the mice up to six months later.

The investigators, led by Jeanne Loring, Ph.D., from the Scripps Research Institute, included scientists from the University of California, Irvine and a group from Australia.

“Our goal was to demonstrate cell therapy for MS,” Dr. Loring told the audience.

According to Ronald Coleman, a graduate student working with Dr. Loring and who is at UC-Irvine, the team used mice infected with a neurotropic JHM variant of mouse hepatitis virus (JHMV) as a model for MS. They injected hNPCs derived from human pluripotent stem cells (hPSC) into the mice to explore treatment options for the disease.

The results were indeed astonishing, said Dr. Loring. Non-control mice were able to move about in a manner that can be described as consistent and long lasting. T-cell proliferation was reduced and T regulatory cell induction took place. The spinal cords of the mice not only did not undergo further demyelination but actually exhibited remyelination. The control mice dragged their legs around when they tried to move.

“The only problem was that the hNPCs themselves are not directly responsible for the cure. They are not even there when the mice start walking,” explained Dr. Loring. “Those cells are rejected after seven days and we start to see a therapeutic response in three weeks.”

Both Dr. Loring and Coleman believe that the hNPCs are secreting proteins, like cytokines, that do the actual repair work in the CNS of the mice.

“We identified a set of candidate proteins secreted by hNPCs and not by undifferentiated pluripotent stem cells,” continued Dr. Loring, who said the team plans to continue building on this initial research.

 

World Stem Cell Summit: December 4, 2013 Update

GEN is on the scene at the World Stem Cell Summit in San Diego. Here are some highlights from the conference so far:

Bernard Siegel, J.D., founder and co-chair of the World Stem Cell Summit (WSCS) and executive director of Genetics Policy Institute, today welcomed attendees of WSCS 2013, being held December 4–6, in San Diego, CA.

“Stem cell science represents, to those afflicted with chronic disease, a vehicle for modeling disease and therapeutic development,” states Siegel in World Stem Cell Report 2013, a supplement to Stem Cells and Development (2013;22;Suppl1). “The field is a true scientific revolution and reflects the transformative power of hope, a powerful engine for progress.”

“The future is here now,” says Mahendra Rao, M.D., Ph.D., director, NIH Center for Regenerative Medicine, who delivered a plenary keynote and moderated the plenary panel discussion, “How Stem Cells are Transforming Medicine.” Cell therapies have been used to treat people safely and effectively; the technical barriers have been addressed. The challenge now is to reduce the cost of manufacturing. To drive routine adoption of cell therapy it must be cost effective and must demonstrate more than incremental benefit, according to Dr. Rao.

Professor Teruo Okano, Ph.D., Tokyo Women’s Medical University, described his group’s Cell Sheet Tissue Engineering strategy that involves enzymatic membrane disruption during cell harvesting and growth of an autologous cell sheet for transplantation on an “intelligent surface” that reversibly changes properties from hydrophobic to hydrophilic with a reversible in temperature from 37°C to 20°C. Dr. Okano further described the development of an automatic tissue factory and thick tissue evaluation system for fully automated, industrialized GMP cell processing.

Andre Terzic, M.D., Ph.D., Center for Regenerative Medicine, Mayo Clinic, noted during the opening session of the WSCS that “the Mayo Clinic has embraced regenerative medicine as a strategy for the future of medicine,” and he described their blueprint for moving from knowledge to delivery of treatments and procedures. Education is a critical dimension of this process. Another important component, according to Dr. Terzic, is the Regenerative Medicine Biotrust, in which “the patient is the center of the solution” to develop combinations of diagnostics and therapeutics and conduct clinical trials.

Regardless of the outcomes of current or future clinical trials, “I would argue that we have already seen breakthroughs,” said Evan Snyder, Ph.D., Sanford-Burnham Medical Research Institute, as stem cells “have completely changed the way medicine thinks about disease and development.” They have led to new views on plasticity and regeneration and the development of different types of drug targets.

WSCS 2013 is organized by the Genetics Policy Institute (GPI), California Institute for Regenerative Medicine (CIRM), Institute for Integrated Cell-Material Sciences at Kyoto University (iCeMS), Mayo Clinic, Sanford-Burnham Medical Research Institute, and The Scripps Research Institute. Mary Ann Liebert, Inc. publishers and Genetic Engineering & Biotechnology News (GEN) are sponsors of the summit.

Drug Testing Should Be with Human iPS Cells
Fri, 12/06/2013 – drug discovery & development  (DDD)

Once established such neural stem cells can be used to continuously generate neurons for drug testing and disease modeling. Depicted is an immunofluorescence staining where proteins characteristic of neural stem cells are labeled with fluorescing antibodies (Nestin in green, Dach1 in red). (Source: Jerome Mertens / Uni Bonn)Once established such neural stem cells can be used to continuously generate neurons for drug testing and disease modeling. Depicted is an immunofluorescence staining where proteins characteristic of neural stem cells are labeled with fluorescing antibodies (Nestin in green, Dach1 in red). (Source: Jerome Mertens / Uni Bonn)Why do certain Alzheimer medications work in animal models but not in clinical trials in humans? A research team from the University of Bonn and the biomedical enterprise Life & Brain GmbH has been able to show that results of established test methods with animal models and cell lines used up until now can hardly be translated to the processes in the human brain. Drug testing should therefore be conducted with human nerve cells, conclude the scientists. The results are published by Cell Press in the journal Stem Cell Reports.

In the brains of Alzheimer’s patients, deposits form that consist essentially of beta-amyloid and are harmful to nerve cells. Scientists are therefore searching for pharmaceutical compounds that prevent the formation of these dangerous aggregates. In animal models, certain non-steroidal anti-inflammatory drugs (NSAIDs) were found to a reduced formation of harmful beta-amyloid variants. Yet, in subsequent clinical studies, these NSAIDs failed to elicit any beneficial effects.

“The reasons for these negative results have remained unclear for a long time”, said Oliver Brüstle, director of the Institute for Reconstructive Neurobiology of the University of Bonn and CEO of Life & Brain GmbH. “Remarkably, these compounds were never tested directly on the actual target cells—the human neuron”, added lead author Jerome Mertens of Brüstle’s team, who now works at the Laboratory of Genetics in La Jolla (USA). This is because, so far, living human neurons have been extremely difficult to obtain. However, with the recent advances in stem cell research it has become possible to derive limitless numbers of brain cells from a small skin biopsy or other adult cell types.

Scientists transform skin cells into nerve cells

Now a research team from the Institute for Reconstructive Neurobiology and the Department of Neurology of the Bonn University Medical Center together with colleagues from the Life & Brain GmbH and the University of Leuven (Belgium) has obtained such nerve cells from humans. The researchers used skin cells from two patients with a familial form of Alzheimer’s Disease to produce so-called induced pluripotent stem cells (iPS cells), by reprogramming the body’s cells into a quasi-embryonic stage. They then transformed the resulting iPS cells into nerve cells.

Using these human neurons, the scientists tested several compounds in the group of NSAIDs. As control, the researchers used nerve cells they had obtained from iPS cells of donors who did not have the disease. Both in the nerve cells obtained from the Alzheimer’s patients and in the control cells, the NSAIDs that had previously tested positive in the animal models and cell lines typically used for drug screening had practically no effect: The values for the harmful beta-amyloid variants that form the feared aggregates in the brain remained unaffected when the cells were treated with clinically relevant dosages of these compounds.

Metabolic processes in animal models differ from humans

“In order to predict the efficacy of Alzheimer drugs, such tests have to be performed directly on the affected human nerve cells”, concluded Brüstle’s colleague Philipp Koch, who led the study. Why do NSAIDs decrease the risk of aggregate formation in animal experiments and cell lines but not in human neurons? The scientists explain this with differences in metabolic processes between these different cell types. “The results are simply not transferable”, says Koch.

The scientists now hope that in the future, testing of potential drugs for the treatment of Alzheimer’s disease will be increasingly conducted using neurons obtained from iPS cells of patients. “The development of a single drug takes an average of ten years”, said Brüstle. “By using patient-specific nerve cells as a test system, investments by pharmaceutical companies and the tedious search for urgently needed Alzheimer medications could be greatly streamlined”.

Date: November 6, 2013
Source: University of Bonn

 

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