Abstract:OBJECTIVE: To explore the protocol that induced marrow mesenchymal stem cells (MSCs) differentiating into islel-secreting cells in vitro and to provide new clues for the sources of islet transplantation. METHODS: Using a defined culture medium and technique for transdifferentiation, MSCs from adult SI) rats were guided into specific insulin-secreting cells. The expressions of nestin and islet-specific hormones and proteins, such as insulin, glucagon, somatoslatin and pancreatic duodenal homeohox 1 (Pdx-1) were analyzed by indirect immunofluorescence cytochemistry staining before and after induction. The expressions of pancreatic islet cell differentiation-related transcripts, such as neslin, insulin 1, glucose transporter 2 (GLUT 2), Isl-f, Pdx-1, Pax-4 mid Pax-6 were detected by reverse transcription-PCR (RT-PCR). In addition, the quantity of insulin secretion was examined using radioinimuna-issay. RESULTS: Five hours after induction, (44.6 ± 7. 3)% of differentiated MSCs expressed nestin and it increased to (61. 8 ± 8. 4)% 24 hs after induction, but the expression of nestin almust disappeared at day 14. In the meantime, islet-like cellular clusters appeared after day 14 and became more apparent by day 28. Differentiated cells were found to be immunoreactive to insulin, glucagon, somalostatin and Pdx-1, and expressed insulin 1, GLUT 2, GK, Isl-1, PDX-1, Pax-4, Pax-6 mRNA. In addition, the results of cumulative quantities of insulin of 24 hs and the stimulation index showed that differentiated cells were able to produce insulin at higher levels, and displayed glucose-dependent insulin release in vitro. CONCLUSIONS: Adult rat MSCs can be differentiated into insulin-secreting cells in vitro. This approach might lead to widespread cell replacement therapy for Type 1 diabetes.
