A better biomaterial for bone regeneration: Type II collagen

Type II collagen is crucial to the development of embryonic skeletal system. Its functional defect in transgenic animal model results in severe chondrodysplasia.¹² The in vitro studies including ours showed that type II collagen promotes chondrogenesis of mesenchymal stem cells (MSCs). ^3-6 Our recent studies have demonstrated that type II collagen also regulated MSC adipogenesis and the early stages of osteogenesis.⁷ Type II collagen-coated surface enhanced osteogenesis-induced MSC calcium deposition, and increased protein expression levels of RUNX2. This mineralization-enhancing effect of type II collagen was diminished by MEK inhibitors. On the other hand, integrin α2β1 presents as the predominant receptor that responses to type II collagen in the osteogenic-induced MSCs. While implanted in the fracture bone of rats, the type II collagen-HA/TCP (nano-particle) scaffold group showed higher SFI scoring of foot-stepping and better locomotion as comparing to that of control group or type I collagen-HA/TCP group did. Collectively, type II collagen serves as an important modulator during early osteogenic differentiation of BMSCs, and enhance bone defect repair through an endochondral ossification-like process. The information advances our understanding about the cartilaginous ECM-BMSC interaction and provides perspective strategies for faster bone regeneration.