Abstract: Objective To investigate the effect of co-expression of bone morphogenetic protein 2 (BMP2) and Sox9 on
chondrogenic differentiation of mesenchymal stem cells (MSCs) in vitro and provide experimental evidence for tissue
engineering of cartilage. Methods Mouse embryonic bone marrow MSC C3H10T1/2 cells were infected with recombinant
adenovirus expressing BMP2, Sox9 and green fluorescent protein (GFP) for 3-14 days, with cells infected with the adenovirus
carrying GFP gene as the control. The mRNA expression of the markers of chondrogenic differentiation, including collagen
type II (Col2a1), aggrecan (ACAN), and collagen type X (Col10a1), were determined by real-time PCR. Alcian blue staining
was used for quantitative analysis of sulfated glycosaminoglycan in the cellular matrix. The expression of Col2a1 protein was
assayed by immunohistochemical staining and Western blot analysis. Results Adenovirus-mediated BMP2 expression induced
chondrogenic differentiation of C3H10T1/2 cells. Overexpression of Sox9 effectively enhanced BMP2-induced expression of the
chondrogenic markers Col2a1, aggrecan and Col10a1 mRNAs, and promoted the synthesis of sulfated glycosaminoglycan and
Col2a1 protein in C3H10T1/2 cells. Conclusion Co-expression of BMP2 and Sox9 can promote chondrogenic differentiation of
MSCs in vitro, which provides a new strategy for tissue engineering of cartilage.