Mesenchymal stem cells contribute to insulin-producing cells upon microenvironmental manipulation in vitro

Background. Extracellular microenvironment and intrinsic genetic programs determine the fate of stem cells. We observed whether mesenchymal stem cells (MSCs) contributed to insulin-producing cells in a manipulated microenvironment. Methods. We delivered pancreatic pieces into Niobium-Coated Dynamatrix to construct a simulated pancreatic microenvironment, upon which soluble cytokine exchange and direct cell-cell contact between MSCs and pancreatic cells could occur. Bone marrow-derived MSCs were cultured upon the microenvironment. Differentiated isletlike cells were observed under an inverted microscope. Insulin in supernates was measurement by enzyme-linked immunosorbent assay. Insulin and c-peptide expression were verified by fluorescent immunocytochemistry and fluorescence in situ hybridization. Apoptosis of isletlike masses in high-glucose DMEM was detected by FACS. Results. After 3 to 4 weeks in culture, typical isletlike masses were observed. Insulin secreted by differentiated cells (414.47 +/- 30.30 mIU/L) was much greater than that of undifferentiated cells (4.89 +/- 1.01 mIU/L; P <.05). Insulin and c-peptide expression were, positive both in protein and mRNA levels. The transdifferentiated isletlike mass did not undergo apoptosis after another 3 weeks of culture in high-glucose DMEM. Conclusion. This simulated injury microenvironment without induction guided MSCs to functional isletlike cells hopefully to replace beta cells.