Long-Term Survival of Poly-L-Lysine-Alginate Microencapsulated Islet Xenografts in Spontaneously Diabetic NOD Mice

Problems with Current Therapy for Diabetes Each year, approximately 15,000 new cases of insulin-dependent diabetes mellitus (IDDM) are diagnosed in the United States. Diabetes-related health care costs are staggering, and the life expectancy of a teenager is reduced by 30 years from the onset of IDDM. For many patients with IDDM, exogenous insulin therapy is not adequate to prevent the complications of the disease. The Diabetes Control and Complications Trial (DCCT) found that intensive insulin therapy delayed the onset and slowed progression of retinopathy, nephropathy, and neuropathy in patients with IDDM.1 Unfortunately, intensive insulin therapy is not appropriate for many IDDM patients, and even with careful monitoring, DCCT patients had increased episodes of severe hypoglycemia, compared to conventionally treated patients.1 Thus, results of the DCCT support the rationale for transplantation of insulinproducing cells. Several investigators are using genetic engineering to introduce the insulin gene into cells such as bone marrow stem cells from a diabetic patient that could be transplanted back into the same patient. However, the physiological regulation of insulin production, processing, and secretion is so complex that gene therapy remains highly experimental. Pancreas or islet transplantation is a more feasible approach for the near future.