Islet transplantation from live or cadaveric donors is used with increasing success to treat patients with insulin-dependent diabetes mellitus (IDDM). However, successful restoration of insulin independence requires > 1x10/6 islets (equivalent to the pancreas of 2 donors) are transplanted. Donations from living donors are restricted to 50% of the donor pancreas, which will likely to only partial restoration of insulin independence. The number of patients with DM that could benefit from islet transplantation far exceeds the number of donor organs available. Therefore, methods for the generation of functioning islets that can be used for transplantation are needed. We have identified rare Multipotent Adult Progenitor Cells (MAPC) in post-natal human, mouse and rat marrow that can be expanded >10/30-fold ex vivo without obvious signs of senescence. They can be induced to differentiate into most mesodermal cell types, as well as cell of neuroectodermal lineage and endodermal lineage. When induced to differentiate to endoderm, we find expression of PDX1 as well as insulin-mRNA, even though the frequency of cells with this phenotype is low. We also shown that PDX1 positive cells can be expanded from exocrine pancreas for a at least 4 months, and be induced to differentiate to insulin-producing islets. This together with recent publications demonstrating that ductal cells can be induced to differentiate to islets lets us hypothesize that MAPC can be coaxed to differentiate to endocrine pancreatic beta cells. Questions to be addressed include, what is the exact nature of MAPC and can these cells be purified to homogeneity? Can MAPC differentiate to pancreas and beta cells, and if so do maturing cells express transcription factors identified to be important in endocrine pancreas differentiation? Can such transcription factors be used to select purified populations that can be used to characterize the expressed gene profile and cell surface characteristics of islet progenitors? Can these progenitors be expanded, induced to differentiate to mature islets that will reverse a diabetic state in vivo? To answer these questions we propose the following aims: SA1: To demonstrate that multi-potent cells exist in post-natal marrow that, at the single cell level marrow that, at the single cell level, can differentiate into cells of mesodermal neuroectodermal and endodermal lineages. SA2: To define culture methods that will support endocrine pancreas differentiation from MAPC SA3: To identify and characterize the cell surface and expressed gene profile characteristics of islet stem cells generated from MAPC.
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