| Objective To evaluate the difference of maturity between insulin- producing cells differentiated from rat pancreatic ductal stem cells, which were isolated and cultured after being purified and identified in vitro, and nature islets, which were obtained from the healthy rat controls. Gene expression profile analysis was performed to observe genes that play important roles during the process of pancreatic ductal stem cells transdifferentiating into insulin- producing cells. To raise the efficiency of pancreatic stem cells differentiating into insulin- producing cells.Methods pancreatic duct stem cells were isolated from the rat pancreas by enzyme digestion protocol, and identified with special marker of cytokeratin- 19(CK-19), pancreatic duodenal homeobox- 1(PDX-1) immunocytochemical staining. The healthy rat pancreas islets were separated and purified with density gradient methods. Dithizone staining was undertaken to identify the insulin- producing cells and nature islets. Regenerated islets were provoked with glucose in vitro to study their insulin secretion ability. The ELISA method was chosed to quantitate insulin secretion level. The C-peptide concentrations in culture medium are monitored at different time intervals. Expression gene profiles of insulin- producing cells induced in vitro and nature islets were compared by rat 22000 sites oligonucleotide array to screen genes which expression level changed significantly.Results The rat pancreatic ductal stem cells cultured in vitro were found to be of CK-19 and PDX-1 immunoreactive positive, which can form the pancreatic islet-like structures and aggregated to be nest-like clusters after differentiation. Insulin containing cells were brick- red after DTZ stains. Analysis of gene expression profile between the induced cells and the rat nature islets showed that, some important genes which participateing in islet development were found significantly down regulation.
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