Cajanine promotes osteogenic differentiation and proliferation of human bone marrow mesenchymal stem cells

Seed cells - mesenchymal stem cells (MSCs) - appear to be an attractive tool in the context of tissue engineering. Bone marrow represents the main source of MSCs for both experimental and clinical studies. However, the number limitation of bone marrow MSCs (BMSCs) and decreased function caused by proliferation make the search for adequate alternative sources of these cells for autologous and allogenic transplant necessary.

This study was aimed to investigate the roles of cajanine isolated from the extracts of Cajanus cajan L. Millsp. in the proliferation and differentiation of BMSCs, and to discover the mechanism of proliferation of BMSCs promoted by cajanine.

Bone marrow mesenchymal stem cells were cultured in high-glucose Dulbecco's Modified Eagle's Medium (DMEM) and osteogenic differentiation was induced by adding dexamethasone, ascorbic acid and β-glycerophosphate supplements. Bone marrow MSCs were cultured in medium without cajanine or supplemented with cajanine. The information about the proliferation and osteogenic differentiation of BMSCs was collated. The osteogenic differentiation potential of BMSCs was also assessed at the 3rd passage by Von Kossa staining. To observe cell signal transduction changes of BMSCs after culturing them with cajanine for 24 h, the western blot analysis was performed to detect phosphorylated cell cycle proteins and activated cyclins.

After osteogenic induction, the differentiation of BMSCs was accelerated by cajanine treatment. Osteogenesis markers were upregulated by cajanine treatment at both protein and mRNA levels. Cajanine obviously promoted the proliferation of BMSCs. After BMSCs were cultured with cajanine for 24 h, the cell cycle regulator proteins were phosphorylated or upregulated.

Cajanine can promote the expansion efficiency of BMSCs, at the same time keeping their multi-differentiation potential. Cajanine can activate the cell cycle signal transduction pathway, thus inducing cells to enter the G1/S phase and accelerating cells entering the G2/M phase. This study can contribute to the development of cajanine-based drugs in tissue engineering.