Type I collagen promotes proliferation and osteogenesis of human mesenchymal stem cells via activation of ERK and Akt pathways

Biomaterials not only serve as scaffolds for bone regeneration, but may also exhibit inductive capability for bone growth. The goal of this study was to identify the best extracellular matrix protein for enhancing osteogenesis by hMSCs (human mesenchymal stem cells) and to investigate the underlying mechanism. Coating with collagen I, but not fibronectin, laminin, gelatin, and poly-L-lysine, enhanced late cell proliferation and promoted osteogenesis by hMSCs, as evidenced by an increase in Alizarin Red S staining, alkaline phosphatase activity and mRNA levels of Runx2 and osteocalcin. Coating with collagen I induced activation of ERK and Akt but not FAK, and treatment with PD98059 and LY294002 blocked the activation of ERK and Akt, respectively. Interestingly, LY294002 also blocked ERK activation, indicating the activation of PI3K/ERK pathway upon contact with collagen I. Furthermore, PD98059 or LY294002 abolished collagen I-induced promotion of osteogenesis by hMSCs. However, blocking antibodies against a2b1 integrins did not inhibit collagen I-induced osteogenesis by hMSCs. These data demonstrate that collagen I promotes proliferation and osteogenesis of hMSCs via activation of ERK and Akt pathways.