Type 1 diabetes, characterized by loss of pancreatic β-cells, can be ameliorated by islet transplantation, but this treatment is restricted by the scarcity of islet tissue as well as allograft rejection. Stem cells are characterized by the ability to renew themselves and to differentiate into a diverse range of specialized cell types, which make them as a promising alternative for the generation of pancreatic islets. Embryonic stem (ES) cells have great potential to differentiate into IPCs, but also have tumorigenesis potential when they are transplanted. Indeed, the development of a simple and reliable procedure to obtain autologous stem cells having the ability to differentiate into functional IPCs would provide a potentially unlimited source of islet cells for transplantation and avoid immune rejection.

Multi-potential skin-derived stem cells from dermis could unlimitedly expand in vitro and differentiate into cells of ectoderm and endoderm, which would be a promising cell source for stem cell therapy for diabetes with their easy accessible and multi-potential.

We isolated and characterized mouse skin-derived precursors (SKPs) - an abundant source of autologous cells, and developed a 3 stage experimental strategy to convert SKPs into insulin-producing cells (IPCs) in vitro within a short period of time through extracellular factor modification. Undifferentiated SKPs (Stage 1) were cultured and expanded as neurospheres in medium containing 20 ng/ml EGF, 40 ng/ml bFGF and 1% B27, the final concentration of glucose was 17.3 mM. At Stage 2, we transferred spheres containing a total of approximately 1-2×105 cells to single wells in plates coated with poly-D-lysine and laminin. These were cultured for 2 days in medium containing 1 mM db-cAMP (cAMP), 1 μM all-trans retinoic acid (RA), 1% B27 and 2% FBS, the final concentration of glucose was 5mM. At Stage 2, SKPs migrated out of the sphere to form a flat monolayer. At Stage 3, cells were cultured in medium supplemented with 10 mM nicotinamide, 10 nM IGF-1, 2nM activin-A, 1% B27 and 2% FBS, the final concentration of glucose was 17.3 mM, for up to 1 week. These differentiated cells in Stage 3 could self-assemble to form three-dimensional islet cell-like clusters (dithizone-positive, DTZ+) and co-express insulin and C-peptide. In addition, they expressed multiple genes related to the development and function of pancreatic β-cell (e.g., Insulin 1, Insulin 2, Islet-1, Pdx-1, NeuroD/beta2, Glut-2 and Nkx6.1), but not other pancreas specific hormones (e.g., Glucagon, Somatostatin and Amylase) by RT-PCR and Immunocytochemistry. Moreover, when stimulated with glucose, IPCs synthesized and secreted insulin in a glucose-regulated manner.　

The results of this work were published in CELL PROLIFERATION 

W. Guo, C. Miao, S. Liu, Z. Qiu, J. Li, and E. Duan* 2009 Efficient differentiation of insulin-producing cells from skin-derived stem cells, Cell Prolif. 42(1):49-62.