Therapeutic potential of stem cells in diabetes

Stem cells possess the ability to self-renew by symmetric divisions and, under certain circumstances, differentiate to a committed lineage by asymmetric cell divisions. Depending on the origin, stem cells are classified as either embryonic or adult. Embryonic stem cells are obtained from the inner cell mass of the blastocyst, a structure that appears during embryonic development at day 6 in humans and day 3.5 in mice. Adult stem cells are present within tissues of adult organisms and are responsible for cell turnover or repopulation of tissues under normal or exceptional circumstances. Taken together, stem cells might represent a potential source of tissues for cell therapy protocols, and diabetes is a candidate disease that may benefit from cell replacement protocols. The pathology of type 1 diabetes is caused by the autoimmune destruction or malfunction of pancreatic beta cells, and consequently, a lack of insulin. The absence of insulin is life-threatening, thus requiring diabetic patients to take daily hormone injections from exogenous sources; however, insulin injections do not adequately mimic beta cell function. This results in the development of diabetic complications such as neuropathy, nephropathy, retinopathy and diverse cardiovascular disorders. This chapter intends to summarize the possibilities opened by embryonic and adult stem cells in regenerative medicine for the cure of diabetes.