Abstract:

BACKGROUND: Islet transplantation is an effective method for the treatment of type 1 diabetes mellitus and parts of type 2 diabetes mellitus. However, its application is hindered by insufficient sources and immunologic rejection. Though transdifferentiation of pancreatic stem cells is at the starting step, it is thought to be the hopeful source for islet cell transplantation.
OBJECTIVE: To look for a suitable cells-transplantation source for the treatment of diabetes mellitus.
METHODS: The pancreatic ductal epithelial cells were separated from Kunming mice and cultured in DMEM/F12 medium supplemented with keratinocyte growth factor, hepatocyte growth factor and nicotinamide, etc. Samples were taken at different time points for light microscopy and electron microscope. The changes of CK-19 and PDX-1 were detected by immunocytochemistry at 1 and 16 days. The expressions of insulin and glucagon gene were detected by RT-PCR at 1 and 16 days. The physiologic function of these islet-like clusters was determined by dithizone staining and glucose stimulation at 21 days. 
RESULTS AND CONCLUSION: A large number of epitheliod cells were CK-19 immunoreactive positive and few of them were PDX-1 positive at 1 day after isolation, then CK-19 positive cells proliferated quickly and formed substantial plaques of epithelial cells in cobblestone pattern. At 16 days later, these cells begin to form islet-like clusters gradually, while most of them were PDX-1 immunoreactive positive. The analysis of mRNA by RT-PCR showed very low levels of insulin and glucagon mRNA in the starting materials but increase was found as the process of transdifferentiation. At 21 day differentiated islet-like clusters were stained red by dithizone. In those samples exposed to a stimulatory 15 mmol/L glucose, there was a 1.6-fold increase in insulin compared with to 5.6 mmol/L glucose (P < 0.05). Pancreatic ductal cells of adult Kunming mice could proliferate quickly and have the potency of transdifferentiation into islet-like clusters when cultured in vitro under appropriate conditions.