The Expression Of Myocardin In Differentiation Of Mouse Bone Marrow Mesenchymal Stem Cell Into Smooth Muscle-like Cells In Vitro

Background Exuberant accumulation of smooth muscle cells (SMC) plays a principal role in the pathogenesis of vascular diseases. The long-standing dogma has been that SMC in atherosclerotic lesions are derived primarily from preexisting medial SMC. Although much effort has been devoted to understanding the molecular pathways regulating migration and proliferation of medial SMC, no effective therapy to prevent occlusive vascular remodeling has been established. It was recently reported that bone marrow cells substantially contribute to the pathogenesis of vascular diseases. It was suggested that bone marrow cells may have the potential to give rise to vascular progenitor cells that home in on the damaged vessels and differentiate them into smooth muscle cells or endothelial cells, thereby contributing to vascular repair, remodeling, and lesion formation. The present findings may provide the basis for the development of new therapeutic strategies for vascular diseases. But the molecular mechanism of bone marrow cells differentiate into SMC is not unclear. However, one exciting advance for the field of SMC differentiation in recent years was the discovery of myocardin, a key transcription factor for SMC differentiation. At present, we have not known a lot about myocardin.Objective To investigate the feasibility of differentiation of bone marrow mesenchymal stem cells(BMSC) into SMC in vitro under PDGF-BB(50μg/L) and high concentrations of FBS(20%), and the positive effect of myocardin on BMSC differentiating into SMC.Methods Mouse BMSC were isolated and purifed from bone marrow by means of adhesion seperation plus digestion control, then PDGF-BB(50μg/L) and FBS(20%)were added to the BMSC. And the cells were cultuted for 4 and 8 days respectively. Immunohistochemistry assay and image analysis were used to value the expression extent ofα-SMA, SM-MHC and myocardin. Meanwhile, cell morphology was observed by inverted phase contrast microscope.Results In morphology, before induction, BMSC were spind-shaped, branch-shaped or polygonal. After 4,8 days induction, most cell were spind-shaped, no big changes with before. But cells were fascl and whirlpool-shaped, similar to SMC. Intensities of the three proteines immunostaining significantly increased after 4 and 8 days. And Test of One-way ANOVA showed that there was statistically significance in different times(p<0.05).Conclusions BMSC could be induced to differentiate into SM-like cells through adding PDGF-BB(50μg/L) and FBS(20%) with BMSC in vitro. Myocardin plays an important role in this process.