Endocrine Abstracts

Bone marrow mesenchymal stem cells (MSCs) have been shown to differentiate into various lineages in vivo and in vitro. Recent reports have shown that adult mouse bone marrow can differentiate toward a pancreatic endocrine beta-cells phenotype; Once engrafted into the host, bone marrow-derived cells exhibit markers and physiological behavior characteristic of pancreatic beta-cells, thus providing a new methods for the therapy and treatment of diabetes. In this study, we explored the protocol that induced MSCs transdifferentiate into islet-secreting cells in vitro. Using a defined culture medium and technique for transdifferentiation, MSCs from adult SD rats were guided into specific insulin- sercreting cells. The expressions of islet-specific hormones and proteins, such as insulin, glucagon, somatostatin and pancreatic duodenal homeobox 1 (PDX-1), were analyzed by indirect immunofluorescence cytochemistry staining before and after induction. And the expressions of pancreatic islet cell differentiation-related transcripts, such as nestin, insulin 1, glucose transporter2 (GLUT2), Isl-1, Pdx-1, Pax-4, Pax-6, were detected by reverse transcription-PCR (RT-PCR). In addition, insulin secretion was examined using radioimmunoassay. After induction for 5h, 44.6±7.3% differentiated MSCs expressed nestin, a marker of neural stem cells, increased 61.8±8.4% at 24h, but disappeared at day 14. 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, somatostatin and PDX-1, and expressed insulin 1, GLUT2, GK, Isl-1, Pdx-1, Pax-4, Pax-6 mRNA. In addition, the results of cumulative quantities of insulin with 24 hours and the stimulation index showed that differentiated cells were able to produce insulin at higher level, and display glucose-dependent insulin release in vitro.These results show that adult rat MSCs can be differentiated to insulin-sercreting cells in vitro. This approach might lead to widespread cell replacement therapy for type 1 diabetes.

Supported by National Natural Science Foundation of China (30200128) and China Postdoctoral Science Foundation.