Advertisements
Feeds:
Posts
Comments

Posts Tagged ‘alginate (seaweed extract)’


Immunopathogenesis Advances in Diabetes and Lymphomas

Larry H Bernstein, MD, FCAP, Curator

LPBI

 

 

 Science team says they’ve taken another step toward a potential cure for diabetes

Wednesday, January 27, 2016 | By John Carroll
Building on years of work on developing new insulin-producing cells that could one day control glucose levels and cure diabetes, a group of investigators led by scientists at MIT and Boston Children’s Hospital say they’ve developed a promising new gel capsule that protected the cells from an immune system assault.

Dr. Jose Oberholzer, a professor of bioengineering at the University of Illinois at Chicago, tested a variety of chemically modified alginate hydrogel spheres to see which ones would be best at protecting the islet cells created from human stem cells.

The team concluded that 1.5-millimeter spheres of triazole-thiomorphine dioxide (TMTD) alginate were best at protecting the cells and allowing insulin to seep out without spurring an errant immune system attack or the development of scar tissue–two key threats to making this work in humans.

They maintained healthy glucose levels in the rodents for 174 days, the equivalent to decades for humans.

“While this is a very promising step towards an eventual cure for diabetes, a lot more testing is needed to ensure that the islet cells don’t de-differentiate back toward their stem-cell states or become cancerous,” said Oberholzer.

Millions of diabetics have effectively controlled the chronic disease with existing therapies, but there’s still a huge unmet medical need to consider. While diabetes companies like Novo ($NVO) like to cite the fact that a third of diabetics have the disease under control, a third are on meds but don’t control it well and a third haven’t been diagnosed. An actual cure for the disease, which has been growing by leaps and bounds all over the world, would be revolutionary.

Their study was published in Nature Medicine.

– here’s the release
– get the journal abstract

 

Long-term glycemic control using polymer-encapsulated human stem cell–derived beta cells in immune-competent mice

Arturo J Vegas, Omid Veiseh, Mads Gürtler,…, Robert Langer & Daniel G Anderson

Nature Medicine (2016)   http://dx.doi.org:/10.1038/nm.4030

The transplantation of glucose-responsive, insulin-producing cells offers the potential for restoring glycemic control in individuals with diabetes1. Pancreas transplantation and the infusion of cadaveric islets are currently implemented clinically2, but these approaches are limited by the adverse effects of immunosuppressive therapy over the lifetime of the recipient and the limited supply of donor tissue3. The latter concern may be addressed by recently described glucose-responsive mature beta cells that are derived from human embryonic stem cells (referred to as SC-β cells), which may represent an unlimited source of human cells for pancreas replacement therapy4. Strategies to address the immunosuppression concerns include immunoisolation of insulin-producing cells with porous biomaterials that function as an immune barrier56. However, clinical implementation has been challenging because of host immune responses to the implant materials7. Here we report the first long-term glycemic correction of a diabetic, immunocompetent animal model using human SC-β cells. SC-β cells were encapsulated with alginate derivatives capable of mitigating foreign-body responses in vivo and implanted into the intraperitoneal space of C57BL/6J mice treated with streptozotocin, which is an animal model for chemically induced type 1 diabetes. These implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control. Implants retrieved after 174 d contained viable insulin-producing cells.

Subject terms: Regenerative medicine  Type 1 diabetes

Figure 1: SC-β cells encapsulated with TMTD alginate sustain normoglycemia in STZ-treated immune-competent C57BL/6J mice.close

(a) Top, schematic representation of the last three stages of differentiation of human embryonic stem cells to SC-β cells. Stage 4 cells (pancreatic progenitors 2) co-express pancreatic and duodenal homeobox 1 (PDX-1) and NK6 homeobox 1…

 

Potential Cure for Diabetes Discovered  
http://www.rdmag.com/news/2016/01/potential-cure-diabetes-discovered   01/27/2016

Two new scientific papers published on Monday demonstrated tools that could result in potential therapies for patients diagnosed with type 1 diabetes, a condition in which the immune system limits the production of insulin, typically in adolescents.  See —

Bubble Technique Could Create Type 1 Diabetes Therapy

http://www.dddmag.com/news/2016/01/bubble-technique-could-create-type-1-diabetes-therapy

Two new scientific papers published on Monday demonstrated tools that could result in potential therapies for patients diagnosed with type 1 diabetes, a condition in which the immune system limits the production of insulin, typically in adolescents.

Previous treatments for this disease have involved injecting beta cells from dead donors into patients to help their pancreas generate healthy-insulin cells, writes STAT. However, this method has resulted in the immune system targeting these new cells as “foreign” so transplant recipients have had to take immune-suppressing medications for the rest of their lives.

The first paper published in the journal Nature Biotechnology explained how scientists analyzed a seaweed extract called alginate to gauge its effectiveness in supporting the flow of sugar and insulin between cells and the body. An estimated 774 variations were tested in mice and monkeys in which results indicated only a handful could reduce the body’s response to foreign invaders, explains STAT.

The other paper in the journal Nature Medicine detailed a process where scientists developed small capsules infused with alginate and embryonic stem cells. A six-month observation period revealed this “protective bubble” technique “began to produce insulin in response to blood glucose levels” after transplantation in mice subjects with a condition similar to type 1 diabetes, reports Gizmodo.

Essentially, this cured the mice of their diabetes, and the beta cells worked as well as the body’s own cells, according to the researchers. Human trials could still be a few years away, but this experiment could yield a safer alternative to insulin injections.

 

Combinatorial hydrogel library enables identification of materials that mitigate the foreign body response in primates

Arturo J Vegas, Omid Veiseh, Joshua C Doloff, et al.

Nature Biotechnology (2016)    http://dx.doi.org:/10.1038/nbt.3462

The foreign body response is an immune-mediated reaction that can lead to the failure of implanted medical devices and discomfort for the recipient1, 2, 3, 4, 5, 6. There is a critical need for biomaterials that overcome this key challenge in the development of medical devices. Here we use a combinatorial approach for covalent chemical modification to generate a large library of variants of one of the most widely used hydrogel biomaterials, alginate. We evaluated the materials in vivo and identified three triazole-containing analogs that substantially reduce foreign body reactions in both rodents and, for at least 6 months, in non-human primates. The distribution of the triazole modification creates a unique hydrogel surface that inhibits recognition by macrophages and fibrous deposition. In addition to the utility of the compounds reported here, our approach may enable the discovery of other materials that mitigate the foreign body response.

 

Video 1: Intravital imaging of 300 μm SLG20 microcapsules.

Video 2: Intravital imaging of 300 μm Z2-Y12 microcapsules.

Video 3: NHP Laparoscopic procedure for the retrieval of Z2-Y12 spheres.

 

Clinical Focus on Follicular Lymphoma: CAR T-Cells Active in Relapsed Blood Cancers

MedPage Today

CAR T-Cells Active in Relapsed Blood Cancers

Complete responses in half of patients

by Charles Bankhead

Patients with relapsed and refractory B-cell malignancies have responded to treatment with modified T-cells added to conventional chemotherapy, data from an ongoing Swedish study showed.

Six of the first 11 evaluable patients achieved complete responses with increasing doses of chimeric antigen receptor (CAR)-modified T-cells that target the CD19 antigen, although two subsequently relapsed.

Five of the six responding patients received preconditioning chemotherapy the day before CAR T-cell infusion, in addition to chemotherapy administered up to 90 days before T-cell infusion to reduce tumor-cell burden. The remaining five patients received only the earlier chemotherapy, according to a presentation at the inaugural International Cancer Immunotherapy Conference in New York City.

“The complete responses in lymphoma patients despite the fact that they received only low doses of preconditioning compared with other published data surprised us,” Angelica Loskog, PhD, of Uppsala University in Sweden, said in a statement. “The strategy of both providing tumor-reductive chemotherapy for weeks prior to CAR T-cell infusion combined with preconditioning just before CAR T-cell infusion seems to offer promise.

CAR T-cells have demonstrated activity in a variety of studies involving patients with B-cell malignancies. Much of the work has focused on patients with leukemia, including trials in the U.S. B-cell lymphomas have proven more difficult to treat with CAR T-cells because the diseases are associated with higher concentration of immunosuppressive cells that can inhibit CAR T-cell activity, said Loskog. Moreover, blood-vessel abnormalities and accumulation of fibrotic tissue can hinder tumor penetration by therapeutic T-cells.

Each laboratory has its own process for modifying T-cells. Loskog and colleagues in Sweden and at Baylor College of Medicine in Houston have developed third-generation CAR T-cells that contain signaling domains for CD28 and 4-1BB, which act as co-stimulatory molecules. In preclinical models, third-generation CAR T-cells have demonstrated increased activation and proliferation in response to antigen challenge. Additionally, they have chosen to experiment with tumor burden-reducing chemotherapy, a preconditioning chemotherapy to counter the higher immunosuppressive cell count in lymphoma patients.

Loskog reported details of an ongoing phase I/IIa clinical trial involving patients with relapsed or refractory CD19-positive B-cell malignancies. Altogether, investigators have treated 12 patients with increasing doses (2 x 107 to 2 x 108 cells/m2) of CAR T-cells. One patient (with mixed follicular/Burkitt lymphoma) has yet to be evaluated for response. The remaining 11 included three patients with diffuse large B-cell lymphoma (DLBCL), one with follicular lymphoma transformed to DLBCL, two with chronic lymphocytic leukemia, two with mantle cell lymphoma, and three with acute lymphoblastic leukemia.

All of the patients with lymphoma received standard tumor cell-reducing chemotherapy, beginning 3 to 90 days before administration of CAR T-cells. Beginning with the sixth patient in the cohort, patients also received preconditioning chemotherapy (cyclophosphamide/fludarabine) 1 to 2 days before T-cell infusion to reduce the number and activity of immunosuppressive cells.

Cytokine release syndrome is a common effect of CAR T-cell therapy and occurred in several patients treated. In general, the syndrome has been manageable and has not interfered with treatment or response to the modified T-cells.

On the basis of the data produced thus far, the investigators have proceeded with patient evaluation and enrollment. They have already begun cell production for the next patient that will be treated with autologous CAR T-cells.

Although laboratories have their own cell production techniques, the treatment strategy has broad applicability to the treatment of B-cell malignancies, said Loskog.

“The results using different CARs and different techniques for manufacturing them is very similar in the clinic, in terms of initial complete response,” she told MedPage Today. “By using 4-1BB as a co-stimulator in the CAR intracellular region, it seems possible to achieve long-term complete responses in some patients. However, preconditioning of the patients with chemotherapy to reduce the regulatory immune cells seems crucial for effect.”

In an effort to manage the effect of patients’ immunosuppressive cells, the investigators have begun studying each the immune profile before and after treatment. Preliminary results suggest that the population of immunosuppressive cells increases over time, which has the potential to interfere with CAR T-cell responses.

“Especially for lymphoma, it may be crucial to deplete such cells prior to CAR infusion,” said Loskog. “It may even be necessary with supportive treatment for some time after CAR T-cell infusion. A supportive treatment needs to specifically regulate the suppressive cells while sparing the effect of CARs.”

The immunotherapy conference is jointly sponsored by the American Association for Cancer Research, the Cancer Research Institute, the Association for Cancer Immunotherapy, and the European Academy of Tumor Immunology.

 

PET-CT Best for FL Response Assessment

PET-CT associated with better progression-free and overall survival rates in follicular lymphoma.

Kay Jackson

PET-CT (PET) rather than contrast-enhanced CT scanning should be considered the new gold standard for response assessment after first-line rituximab therapy for high-tumor burden follicular lymphoma (FL), a pooled analysis of a central review in three multicenter studies indicated.

Advertisements

Read Full Post »