Enhancement of osteogenesis by concanavalin A in human bone marrow mesenchymal stem cell cultures

This study investigates concanavalin A (ConA) as a novel factor that may enhance osteogenesis of mesenchymal stem cells (MSCs) in vitro. Various factors, such as cytokine bone morphogenetic protein-2 (BMP-2), have been studied for their possible promotion of MSC osteogenesis in vivo and in vitro. However, the factor that might be safer, more effective, and less expensive than these has not been determined. We therefore cultured human MSCs in osteogenic medium in the presence or absence of ConA, and used calcium assays to compare the effects of ConA and BMP-2 on MSC calcification. We also used enzyme-linked immunosorbent assay (ELISA) and quantitative polymerase chain reaction (PCR) to evaluate the expression levels of bone-specific markers. ConA and BMP-2 enhanced calcification with comparable effectiveness. The combination of ConA and BMP-2 further enhanced calcification slightly but significantly. ConA also increased osteocalcin and BMP-2 protein levels in MSC culture medium. Furthermore, ConA increased osteocalcin, RUNX2, BMP-2, BMP-4, and BMP-6 mRNA expression levels. However, the gene expression pattern of ConA-stimulated MSCs was different from that of MSCs stimulated by BMP-2. Together, these results suggest that ConA and BMP-2 enhance MSC osteogenesis via different pathways. ConA-induced bone formation in MSC cultures may be useful in regenerative medicine or tissue engineering in clinical studies, as well as in basic research on bone formation.