Vijayakumar K. Ramiya

Reversal of insulin-dependent diabetes using islets generated in vitro from pancreatic stem cells

Ductal structures of the adult pancreas contain stem cells that differentiate into islets of Langerhans. Here, we grew pancreatic ductal epithelial cells isolated from prediabetic adult non-obese diabetic mice in long-term cultures, where they were induced to produce functioning islets containing α, β and δ cells. These in vitro-generated islets showed temporal changes in mRNA transcripts for islet cell-associated differentiation markers, responded in vitro to glucose challenge, and reversed insulin-dependent diabetes after being implanted into diabetic non-obese diabetic mice. The ability to control growth and differentiation of islet stem cells provides an abundant islet source for β-cell reconstitution in type I diabetes.

Murine Antithymocyte Globulin Therapy Alters Disease Progression in NOD Mice by a Time-Dependent Induction of Immunoregulation

OBJECTIVE—Antilymphocyte serum can reverse overt type 1 diabetes in NOD mice; yet, the therapeutic parameters and immunological mechanisms underlying the ability for this agent to modulate autoimmune responses against β-cells are unclear, forming the rationale for this investigation. RESEARCH DESIGN AND METHODS—A form of antilymphocyte serum, rabbit anti-mouse thymocyte globulin (mATG), was utilized in a variety of in vivo and in vitro settings, each for the purpose of defining the physiological, immunological, and metabolic activities of this agent, with particular focus on actions influencing development of type 1 diabetes. RESULTS—We observed that mATG attenuates type 1 diabetes development in an age-dependent fashion, only proving efficacious at disease onset or in the late pre-diabetic phase (12 weeks of age). When provided at 12 weeks of age, mATG reversed pancreatic insulitis, improved metabolic responses to glucose challenge, and rapidly increased frequency of antigen-presenting cells in spleen and pancreatic lymph nodes. Surprisingly, mATG therapy dramatically increased, in an age-dependent fashion, the frequency and the functional activity of CD4+CD25+ regulatory T-cells. Adoptive transfer/cotransfer studies of type 1 diabetes also support the concept that mATG treatment induces a stable and transferable immunomodulatory repertoire in vivo. CONCLUSIONS—These findings indicate that an induction of immunoregulation, rather than simple lymphocyte depletion, contributes to the therapeutic efficacy of antithymocyte globulin and suggest that time-dependent windows for the ability to delay or reverse type 1 diabetes exist based on the capacity to enhance the functional activity of regulatory T-cells.

Effect of Oral and Intravenous Insulin and Glutamic Acid Decarboxylase in NOD Mice

Islet cell antigens have been administered orally and intravenously (I.V.) to NOD mice to assess their abilities to protect from or delay the onset of diabetes, and thereby provide insights that may have therapeutic implications in human trials. Whereas we and others have observed a delay in the onset of diabetes in NOD mice that have been fed with insulin from early life, we report here for the first time that feedings with porcine GAD65 alone (p = 0.226) or in combination with insulin (p = 0.011), have anti-diabetic effects in a prolonged study period (>400 days). While antigen-specific inhibitions of in vitro lymphocytic proliferation responses were seen (p < 0.05), antibody levels were unaffected by oral antigen treatments. IFN-gamma mRNA levels were downregulated in the islet infiltrates following oral antigen treatments while IL-2 and TNF-beta were expressed in all instances. We also observed that I.V. human recombinant GAD65, and porcine GAD given at weaning, delayed diabetes onset (p = 0.004) while similar treatments with a variety of inactive insulin preparations were generally ineffective. These findings thus indicate varying effects of oral and I.V. autoantigen administrations on the development of diabetes in NOD mice, and describe the immunological processes induced by oral autoantigen treatments.

Pancreatic stem cells: building blocks for a better surrogate islet to treat type 1 diabetes

Type 1, insulin-dependent, diabetes is one of the more costly chronic diseases of children, adolescents and adults in Europe and North America. While routine insulin injections currently provide diabetic patients with their daily insulin requirements, blood glucose excursions are common, leading eventually to microvascular and macro-vascular complications and early death. A ‘cure’ for Type 1 diabetes relies on replacement of the beta-cell mass which, today, is accomplished by pancreas transplants or islets of Langerhans implants. Recent advances in the isolation of stem cells that possess the capacity to differentiate to functional endocrine pancreas provide new opportunities to produce large numbers of islets, even autologous islets, that can be used as implants. We discuss briefly this new technology and its meaning for diabetes.

Use of In Vitro-Generated, Stem Cell-Derived Islets to Cure Type 1 Diabetes

Abstract: Recent successes in treating type 1 diabetic patients with islet transplantation portends a future need for an increase in available islets. Ductal structures of the adult pancreas contain multipotent stem cells that, under the proper in vitro conditions, can both self‐renew and differentiate into functional islets of Langerhans. In vitro‐generated islets exhibit temporal changes in mRNA transcripts for islet‐associated markers as well as regulated insulin responses following glucose challenge. When implanted into diabetic mice, in vitro‐generated islets induce neovascularization and reverse insulin‐dependent diabetes. The possibility of growing functional endocrine pancreas from stem cells provides new opportunities to produce large numbers of islets, even autologous islets, for use as implants.

Islet replacement vs. regeneration: hope or hype?

Abstract:u2002 Type 1 diabetes is caused by autoimmune destruction of pancreatic islet β‐cells. Management of this disease is burdensome both to the individual and society, costing over

Pancreatic stem cells: a therapeutic agent that may offer the best approach for curing type 1 diabetes

100 billion annually. Shortage of pancreatic tissue, together with a lifetime requirement of immunosuppressive drugs to prevent rejection and recurrent disease, remain as major hurdles yet to be overcome prior to widespread applicability. Stem cells, with their potential of developing into pancreatic β‐cells, appear to be the best prospect for overcoming the islet shortage. Current investigation, however (both embryonic and adult stem cells), is still in the preliminary stage and several more years remain before they can potentially be used in the clinical setting. Procedures that reduce in vitro manipulation of cells and allow stem cells to develop into islets in vivo are crucial. Furthermore, the regeneration of existing islets is a distinct possibility. Simplistically, it might be hypothesized that down‐regulation of autoimmunity may give the pancreas the breathing space to regenerate islets. Supplementation with factors known to induce β‐cell replication and neogenesis might further augment the regenerative processes. Clearly, islet‐regeneration research will soon match the level of interest currently focused on in vitro stem cell‐based approaches.

Insulin Prophylaxis in Insulin-Dependent Diabetes Mellitus

Chaudhari M, Cornelius JG, Schatz D, Peck AB, Ramiya VK. Pancreatic stem cells: a therapeutic agent that may offer the best approach for curing type 1 diabetes.

Immunotherapies in diabetes

All the experimental animal models of insulin-dependent diabetes mellitus (IDDM) and preliminary human trials suggest that insulin can be safely used not only for immediate therapeutic purposes but also in the prevention of the disease. The mechanism of protection induced by insulin prophylaxis may include both ‘β-cell rest’ and induction of immunoregulatory processes. Finally, combined therapies involving oral, subcutaneous and intravenous routes may be of potential advantage in disease prevention. Future studies will have to address these issues.

Plasticity of Adult-Derived Pancreatic Stem Cells

Insulin-dependent diabetes (IDD) is a serious, life-long disease replete with life-threatening complications that are not preventable through conventional insulin replacement therapies. The prolonged prodromal period of autoimmunity to beta cell antigens offers multiple intervention opportunities. These can target different steps that precede final destruction of insulin-secreting beta cells and clinical onset of the disease. All current and proposed immunotherapies are experimental procedures that have proven to be protective in animal models, especially the nonobese diabetic (NOD) mouse. This brief review deals with a selected list of nonspecific and autoantigen-specific immunotherapies that may bring hope in the near future to individuals at risk of developing the disease. None are yet proven to be effective in humans.