Effects of cartilage oligomeric matrix protein on BMP-2 induced cell differentiation of mesenchymal stem cells

Abstract

Objective To investigate the effect of overexpression of cartilage oligomeric matrix protein (COMP) on BMP-2 induced cell osteogenic and chondrogenic differentiation of mesenchymal stem cells (MSCs). Methods MSCs, transfected with plasmid DNA encoding recombinant human COMP, were induced to differentiate into osteocytes and chondrocytes by BMP-2. Realtime PCR of osteogenic related markers (Col1a1, RUNX2, OPN, BGP) and chondrogenic related markers (Col2a1, SOX9, Aggrecan) were performed to evaluate the process of cell differentiation. ALP staining, Alizarin red S staining for osteogenic differentiation and alcian blue staining for chondrogenic differentiation were conducted to evaluate the tendency of cell differentiation. Results Real-time PCR assay presented the significantly higher (P<0.05) COMP expression of MSCs when COMP gene was transfected into cells. The expression level of OPN was significantly (P<0.05) down-regulated at all the time points in experimental-group compared with that in control group. A final significant (P<0.05) up-regulation of expression appeared in experimental group at the late stage of induction (day 7, 14) compared with that in control group, even though a decrease (P<0.05) expression of Col1a1, RUNX2 and BGP in experimental group occurred at the early stage of induction (day 3). The expression of Aggrecan and Col2a1 in experimental group was up-regulated (P<0.05) at different time points compared with that in control group. And a significant higher (P<0.05) expression of SOX9 in experimental group only appeared at day 7 compared with that in control group. ALP staining and Alizarin red S staining were weakened while alcian blue staining was enhanced. Conclusion COMP may inhibit BMP-2 induced osteogenic differentiation and promote BMP-2 induced chondrogenic differentiation, which may provide new insight for cartilage tissue engineering. Key words: Extracellular matrix proteins; Bone morphogenetic protein 2; Mesenchymal stem cells; Cell differentiation; Gene expression