Stem Cell Therapy for Islet Regeneration

Abstract

Diabetes mellitus is an endocrine disorder characterised by inadequate production or use of insulin, resulting in abnormally high blood glucose levels. High blood glucose leads to the formation of reactive advanced glycation end-products (Feldman et al., 1997), which are responsible for complications such as blindness, kidney failure, cardiovascular disease, stroke, neuropathy and vascular dysfunction. Diabetes mellitus is classified as either type 1 or type 2. Type 1 diabetes mellitus (insulin-dependent diabetes mellitus) results from the autoimmune destruction of the pancreatic beta cells, whereas type 2 diabetes mellitus (noninsulin-dependent diabetes mellitus) results from insulin resistance and impaired glucose tolerance. Approximately 7.8% (23.6 million people) of the US population has been diagnosed with diabetes mellitus, and another 57 million people are likely to develop diabetes mellitus in the coming years (American Diabetes Association, 2007). The number of people with diabetes mellitus is set to continue to rapidly increase between now and 2030, especially in developing countries. Over the last decade, a new form of treatment called islet transplantation therapy was thought to provide good patient outcomes; however, few islets are available for transplantation. Typically, the pooled islets isolated from two pancreases are enough to treat a single patient. Since the enormous potential of stem cells was discovered, it was hoped that they would provide the most effective treatment for diabetes mellitus. Over the past two decades, hundreds of studies have looked at the potential of stem cell therapy for treating diabetes mellitus. Successful stem cell therapy would eliminate the cause of the disease and lead to stable, long-term results; hence, the term “pancreatic regeneration” was coined. The hypothesis was that stem cells could regenerate the damaged pancreas. After careful consideration of the aetiology of diabetes mellitus, scientists have put forward two general treatment strategies: stem cell therapy to treat the autoimmune aspect of the disease, and stem cell therapy to treat the degenerative aspect of the disease. In this review, we focus on stem cell-based therapies aimed at islet regeneration through stem cell or insulinproducing cell (IPC) transplantation. We will also discuss the latest strategies for treating both type 1 and type 2 diabetes mellitus using stem cell therapy, along with the (initially promising) results.