The Study On Neural Cells Differentiation Of Bone Marrow Mesenchymal Stem Cells Induced By Retinoic ACID

Bone marrow mesenchymal stem cells(BMSCs) are ideal for transplantation because they can be conveniently isolated from wide variety of tissues and, don’t stimulate an immune-rejection response. To induce BMSCs differentiation into neural cells will offer an experimental foundation for the clinical treatment of neurodegenerative diseases and the repair of central nervous system injury. In this paper, we isolate and culture rat BMSCs in vitro and reaserch the mechanism by which Retinoic Acid (RA) inhibit the BMSCs proliferation and promote their differentiation into neural cells.BMSCs are separated and purified by density gradient centrifugation method and fully adherent culture method. BMSCs that are in low abundance in vivo can grow quickly when cultured in vitro, density gradient centrifugation is an appropriate method to purify BMSCs.We treated BMSCs with RA and optimized differentiation conditions by adding bFGF to media. The optimal concentrations of RA were determined by morphology observation and MTT method. The data of RT-PCR and immunocytochemistry showed that RA could induce BMSCs differentiation into neural cells and the differentiated cells exhibited positive NSE, GAFP and MAP-2expressions. Therefore, bFGF can significantly improve the cell survival rate of BMSCs and protect differentiated neural cells,but can not improve the differentiation rate of BMSCs.The RT-PCR data showed that the mRNA levels of RXRa was increased in the RA-treated BMSCs. The results indicated that RXRa was involved in the neural cell differentiation of BMSCs induced by RA.The mRNA levels of Myocardin and MRTF-A were increased in the RA-treated BMSCs. The results indicated that Myocardin and MRTF-A were also involved in the neural cells differentiation of BMSCs induced by RA. We competitive inhibit the function of endogenous Myocardin by transfecting Myocardin dominant negative plasmid into BMSCs. The results showed that after the function of endogenous Myocardin was blocked, the RA-induced differentiation rate was significantly lower. The results confirmed that RA-induced BMSCs differentiation to neural cells was partially dependent on Myocardin.The mRNA levels of cyclin-El and P21were examined by RT-PCR. The data showed that the level of P21was increased while the level of cyclin-El was decreased during RA-induced BMSCs differentiation process. The results showed that RA could inhibit BMSCs proliferation and promote differentiation by up-regulating the expression of P21and down-regulating the expression of cyclin-El.