Stem cells present a potential solution to the opposite requirements of cell propagation and function. Diabetes is a syndrome that is characterized by confused metabolism and inappropriately high blood sugar produced by either low levels of the hormone insulin or from abnormal resistance to insulin's effects together with insufficient levels of insulin secretion to recompense. As a rule, the signs are extreme urine production, excessive thirst and greater than before fluid intake, and blurred vision; these signs are likely absent if the blood sugar is only mildly elevated.
The modern best medical practice for those with type 1 diabetes comprises insulin by multiple daily injections or continuous pump infusion. Lately developed insulin analogues have helped to more closely approximate normal glucose homeostasis and have been particularly helpful in lowering hypoglycaemia while strongly controlling blood glucose. Glargine insulin provides nearly 24 hours of low level basal insulin activity, at the same time as meal-time peaks in activity can be mimicked by administration of rapid acting insulin analogues like lispro and aspart insulins. Delivery of insulin by permanent infusion pump allows even finer tuning of insulin activity.
Although current insulin delivery modalities are quite good and improving, limitations still exist. Regular self-monitoring of blood glucose is still needed, as is estimation of insulin doses based on multiple factors that might affect future glycaemic changes.
Stem cells present a potential solution to the opposed requirements of cell proliferation and function. Theoretically, these cells can reproduce in an undifferentiated condition and then be transformed to take on necessary metabolic functions through genetic and epigenetic manipulations. Stem cells have been detached from embryonic tissues as well as a diversity of fetal and adult sources, including umbilical cord blood, bone marrow, central nervous system, liver and pancreas. One potential benefit of adult stem cells is that they could be used for autologous transplantation. This might prevent the use of immunosuppressive medicines to avert allorejection. Nevertheless, recurrent autoimmune-mediated destruction targeting cell proteins would remain problematic.
Xenogeneic cells are a potential source of cells for transplantation therapy. Because pigs regulate glucose in a similar physiological range to that of humans, and because porcine insulin has been used as an exogenous source of insulin, pigs are generally considered the most promising donor animal. On the other hand, islets from xenogeneic pancreata are more immunogenic than allogeneic islets.
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