Progress in islet transplantation in patients with type 1 diabetes mellitus

CORM-2 Pretreatment Attenuates Inflammation-mediated Islet Dysfunction

During the process of human islet isolation a cascade of stressful events are triggered and negatively influence islet yield, viability, and function, including the production of proinflammatory cytokines and activation of apoptosis. Carbon monoxide-releasing molecule 2 (CORM-2) is a donor of carbon monoxide (CO) and can release CO spontaneously. Accumulating studies suggest that CORM-2 exerts cytoprotective and anti-inflammatory properties. However, the effect of CORM-2 on islet isolation is still unclear. In this study, we found that CORM-2 pretreatment significantly decreased the expression of critical inflammatory genes, including tissue factor, intercellular adhesion molecule-1, chemokine (C-C motif) ligand 2, C-X-C motif chemokine 10, Toll-like receptor 4, interleukin-1β, interleukin-6, and tumor necrosis factor-α (TNF-α). The isolated islets of the CORM-2 pretreatment group showed reduced apoptotic rate, improved viability, and higher glucose-stimulated insulin secretion, and functional gene expression in comparison to control group. Importantly, CORM-2 pretreatment prevented the impairment caused by TNF-α, evidenced by the improved glucose-stimulated index and transplantation outcomes. The present study demonstrated the anti-inflammatory property of CORM-2 during human islet isolation, and we suggest that CORM-2 pretreatment is an appealing treatment to mitigate inflammation-mediated islet dysfunction during isolation and culture ex vivo and to preserve long-term islet survival and function.

RGD-modified injectable hydrogel maintains islet beta-cell survival and function

OBJECTIVE

A potential solution for islet transplantation and drug discovery vis-à-vis treating diabetes is the production of functional islets in a three-dimensional extracellular matrix. Although several scaffold materials have been reported as viable candidates, a clinically applicable one that is injectable and can maintain long-term functionality and survival of islet pancreatic beta-cells (β-cells) is far from being established.

RESULTS

In the current study, we evaluated a ready-to-use and injectable hydrogel's impact on β-cells' function and viability, both in vitro and in vivo. We found that β-cells in high concentration with hydrogels functionalized via Arg-Gly-Asp (RGD) demonstrated better viability and insulin secretory capacity in vitro. Moreover, it is a biocompatible hydrogel that can maintain β-cell proliferation and vascularization without stimulating inflammation after subcutaneous injection. Meanwhile, modifying the hydrogel with RGD can maintain β-cells' secretion of insulin, regulating the blood glucose levels of mice with streptozotocin-induced diabetes.

CONCLUSIONS

Thus, these preliminary results indicate that this RGD-modified hydrogel is a potential extracellular matrix for islet transplantation at extrahepatic sites, and they also provide a reference for future tissue engineering study.

Glucose-regulated insulin production in the liver improves glycemic control in type 1 diabetic mice

OBJECTIVE

Type 1 diabetes results from autoimmune destruction of beta-cells in the pancreas. Our objective is to reconstitute a glucose-responsive system in the liver to regulate hepatic insulin production for improving glycemic control in type 1 diabetes.

METHODS

We have cloned the glucose-responsive element (GRE) from the promoter of acetyl-CoA carboxylase (ACC), an enzyme that catalyzes the rate-limiting step in fatty acid synthesis in the liver in response to glucose. To increase the amplitude of glucose induction, we quadruplicated the GRE DNA by gene duplication. The resulting GRE multimer (4×GRE) was tested for its ability to drive rat proinsulin cDNA expression in hepatocytes and insulin-deficient diabetic mice.

RESULTS

We showed that this GRE multimer-directed glucose-responsive system produced insulin in hepatocytes in a glucose-dependent manner. When delivered into the liver by adenovirus-mediated gene transfer, this glucose-responsive insulin production system was able to reverse hyperglycemia to a normal range without causing hypoglycemia after glucose challenge or overnight fasting. Insulin vector-treated diabetic mice exhibited significantly improved blood glucose profiles in response to glucose tolerance, correlating with insulin production in the liver. We recapitulated these findings in streptozotocin-induced diabetic CD1 mice and autoimmune non-obese diabetic mice.

CONCLUSION

Our data characterized the GRE motif from the ACC promoter as a potent glucose-responsive element, and provided proof-of-concept that the 4×GRE-mediated hepatic insulin production is capable of correcting insulin deficiency and improving glycemic control in type 1 diabetes.

Pdx1 and controlled culture conditions induced differentiation of human amniotic fluid-derived stem cells to insulin-producing clusters

This study investigated the differentiation of human amniotic fluid-derived stem cells (hAFSCs) into insulin-producing clusters in vitro. Adenovirally-delivered mouse Pdx1 (Ad-Pdx1) induced human Pdx1 expression in hAFSCs and enhanced the coordinated expression of downstream β-cell markers. When Ad-Pdx1-transduced hAFSCs were sequentially treated with activin A, bFGF and nicotinamide and the culture plate surface coated with poly-l-ornithine, the expression of islet-associated human mRNAs for Pdx1, Pax6, Ngn3 and insulin was increased. C-peptide ELISA confirmed that Ad-Pdx1-transduced hAFSCs processed and secreted insulin in a manner consistent with that pathway in pancreatic β-cells. To sustain the β-cell-like phenotype and investigate the effect of three-dimensional (3D) conformation on the differentiation of hAFSCs, Pdx1-transduced cells were encapsulated in alginate and cultured long-term under serum-free conditions. Over 2 weeks, partially differentiated hAFSC clusters increased in size and increased insulin secretion. Taken together, these data demonstrate that ectopic Pdx1 expression initiates pancreatic differentiation in hAFSCs and that a β-cell-like phenotype can be augmented by culture conditions that mimic the stromal components and 3D geometry associated with pancreatic islets.

Diabetes treatment in 2025: can scientific advances keep pace with prevalence?

Despite the known benefits of a healthy lifestyle, many individuals find it hard to maintain such a lifestyle in our modern world, which facilitates sedentary behavior and overeating. As a consequence, the prevalence of type 2 diabetes mellitus is predicted to increase dramatically over the coming years. Will developments in treatments be able to counteract the resulting impact on morbidity and mortality? The various lines of research can be grouped into three main categories: technological, biological, and pharmacological. Technological solutions are focused on the delivery of insulin and glucagon via an artificial pancreas, and components of the system are already in use, suggesting this option may well be available within the next 10 years. Of the biological solutions, pancreas transplants seem unlikely to be used widely, and islet cell transplants have also been hampered by a lack of appropriate donor tissue and graft survival after transplant. However, significant progress has been made in these areas, and additional research suggests manipulating other cell types to replace beta cells may be a viable option in the longer term. The last category, pharmacological research, appears the most promising for significantly reducing the burden of type 2 diabetes mellitus. In recent years, research has concentrated on reducing blood glucose, and the increasing pace of research has been reflected in a growing number of antidiabetic agents. In the past few years, studies of the complementary approach of protecting cells from the damaging effects of high blood glucose have also been reported, as has research into the control of energy intake and energy expenditure. Evidence from studies of dietary restriction and bariatric surgery suggests it may be possible to reset metabolism to effectively cure diabetes, and research into pharmacological agents that could selectively restore energy balance is currently the most exciting prospect for future treatments for people with type 2 diabetes mellitus.

Understanding pancreas development for β-cell repair and replacement therapies

The lack or dysfunction of insulin-producing β-cells is the cause of all forms of diabetes. In vitro generation of β-cells from pluripotent stem cells for cell-replacement therapy or triggering endogenous mechanisms of β-cell repair have great potential in the field of regenerative medicine. Both approaches rely on a thorough understanding of β-cell development and homeostasis. Here, we briefly summarize the current knowledge of β-cell differentiation during pancreas development in the mouse. Furthermore, we describe how this knowledge is translated to instruct differentiation of both mouse and human pluripotent stem cells towards the β-cell lineage. Finally, we shortly summarize the current efforts to identify stem or progenitor cells in the adult pancreatic organ and to harness the endogenous regenerative potential. Understanding development and regeneration of β-cells already led to identification of molecular targets for therapy and informed on pathomechanisms of diabetes. In the future this knowledge might [corrected] lead to β-cell repair and replacement therapies.

Oleanolic Acid, a plant triterpenoid, significantly improves survival and function of islet allograft

BACKGROUND.: Oleanolic acid (OA) is a ubiquitous triterpenoid, with potent antioxidant and anti-inflammatory properties. Here, we tested whether these combined properties of OA can prevent nonimmunologic primary nonfunctioning and immunologic phenomena ascribed to graft rejection hence prolong islet allograft survival. METHODS.: Islet transplants were performed under kidney capsule of streptozotocin-induced diabetic C57BL/6 mice with BALB/c islets. Recipients were treated with 0.5 mg/day of OA intraperitoneally, and serum samples were collected once in 2 days and used for luminex, ELISA, and donor-specific antibody screening. Transplanted mice were killed at different time intervals to obtain splenocytes and kidney samples for ELISPOT, mixed leukocyte reaction, and immunohistochemical studies. RESULTS.: After transplantation, the decrement of blood glucose was significantly faster in mice receiving OA less than 2+/-1 days compared with untreated (4+/-2 days). OA prolonged survival of transplanted islets up to 23+/-3 days and reversed diabetes even with 250 islets. Treatment group showed increased serum interleukin (IL)-10 (twofold) and decreased inducible protein-10 and IL-4 (threefold) in luminex. Significantly reduced frequency of interferon-gamma (4.5-fold), IL-4 (3.5-fold), IL-2 (2.3-fold), and IL-17 (fourfold) producing T-cell populations were found in ELISPOT. OA-treated grafts had significant reduced and delayed infiltration of CD4+ and CD8+ T cells. OA also delayed donor-specific antibody generation up to 19 days after transplantation. Combined treatment with cyclosporine A, OA further prolonged the islet allograft survival to 34+/-3 days. CONCLUSIONS.: In conclusion, OA is an attractive, dietary nontoxic plant triterpenoid, which suppresses the production of proinflammatory cytokines and delays graft-specific immune responses to prolong islet allograft survival.

Would pancreas duct-epithelium-derived stem/progenitor cells enhance islet allograft survival by means of islets recruitment and tolerance induction in Edmonton protocol era?

Rates of insulin independence at 1 year with current Edmonton protocol are impressive. However, obstacles such as the restricted availability of donor pancreas, coupled with recipient's pharmacologic immunosuppression, have lent strong impetus to the search for new sources of insulin-producing cells. But work with stem cells has not yet produced cells with the phenotype of true beta cells. Recently the data have shown that the presence of duct-epithelium in clinical islet transplantation may improve the long-term metabolic outcome. The underlying mechanisms are not well understood. The pancreatic duct-epithelium has been considering as a pool of pancreatic stem/progenitor cells, cytokeratin-19 positive stem cells, which have been proved to be capable of differentiating into endocrine cells and inducing immune tolerance. Based on these findings, we speculate that pancreatic stem/progenitor cells derived from ductal epithelium may enhance islet allograft survival through two aspects: islet recruitment and tolerance induction. The proposition may have clues on the further improvement in clinical islet transplantation long-term outcome.