The Role Of LDL In The Process Of Bone Marrow Stromal Cells Differentiation Into Smooth Muscle-Like Cells

Background Atherosclerosis (As) is the pathologic basis of many vascular diseases. In the process of As,smooth muscle cell(SMC) proliferating and synthesizing extracellular matrix is an important component,due to factors such as the high-fat. Traditional concepts that smooth muscle cells of lesions site come from the medial layer of the diseased artery. However, recent research results showed that the smooth muscle cells in the lesion site are not completely from the the medial layer of the diseased artery, bone marrow-derived cells in certain circumstances can be directed to differentiate into smooth muscle cells and involved in atherosclerosis occurring and developmentObjective To investigate the differentiation of marrow stromal cells induced by LDL into smooth muscle-like cells and the role of myocardin. Methods Bone marrow stromal cells(BMSC) of mouse were purified by disparation adherence technique. The cultured BMSC were divided into 4 groups:①regular culture group(L-DMEM, 3%Gln, 10%FBS),②r egular culture+LDL group(25mg/L),③20%FBS culture group,④20%FBS culture + LDL group. The cells in group②and④were cultured for 24hours, 48 hours and 72 hours respectively, after joined LDL. Each group were cultured 96 hours. Smooth muscle cells specific markersα-SMA, and SM-MHC were detected by immunocytochemistry technique to identify the smooth muscle-1ike cells and myocardin was also detected at different time point. RT-PCR was used to detect the mRNA expression of myocardin,α-SMA and SM-22α.Results Light microscopy showed that BMSCs gradually extended with the induction time from the small circle with the polygon into a long spindle . It is showed by immunocytochemistry that the positive cells rate of myocardin,α-SMA and SM- MHC in the regular culture + LDL group, 20%FBS culture group, 20%FBS culture + LDL group were signifcantly higher than that regular culture group(P <0. 05, n=9).Culturing with the same serum concentrations, the expression of the three proteins were the strongest at LDL for 48hours. LDL role at the same time, 20% FBS culture + LDL stimulated group were signifcantly higher than that regular culture+ LDL stimulated group (P<0. 05, n=9). The proteins expression ofα-SMA (r=0.9018, P<0.05) and SM-MHC(r=0.7969, P<0.05) were positively correlated myocardin. It is approved by RT-PCR that the mRNA expression of myocardin,α-SMA and SM-22αin the regular culture + LDL group, 20%FBS culture group and 20%FBS culture + LDL group were signifcantly higher than that regular culture group(P<0. 05, n=9).Culturing with the same serum concentrations, the mRNA expresion of the three genes were the strongest at LDL for 48 hours. LDL role at the same time, the mRNA expression of the three genes in the 20% FBS + LDL groups were signifcantly higher than that in the regular culture + LDL groups(P<0. 05, n=9). The mRNA expression ofα-SMA and SM-22αwere positively correlated with myocardin (r=0. 9295, P<0. 05; r=0. 8940, P <0. 05).Conclusion Both LDL and 20%FBS could induce the differentiation of BMSCs into smooth muscle-like cells. The role of LDL with 20%FBS induce the differentiation of BMSCs into smooth muscle-like cells was the strongest. And myocardin may play an important role in this differentiated process.