Effect of magnesium ions/Type I collagen promote the biological behavior of osteoblasts and its mechanism

Type I collagen (Col I) is a main component of extracellular matrix (ECM). Its safety, biocompatibility, hydrophilicity and pyrogen immunogenicity make it suitable for tissues engineering applications. Mg(2+) also control a myriad of cellular processes, including the bone development by enhancing the attachment and differentiation of osteoblasts and accelerating mineralization to enhance bone healing. In our studies, Mg(2+) bind collagen to promote the proliferation and differentiation of osteoblasts through the expression of integrins and downstream signaling pathways. In order to clarify the biological behavior effect of 10 mM Mg(2+)/Col I coating, we performed 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline phosphatase (ALP), 4′6-diamidino-2-phenylindole (DAPI), Alizarin red staining and Rhodamine B-isothiocyanate (RITC)-labeled phalloidin experiments and found that 10 mM Mg(2+) group, Col I-coating group, 10 mM Mg(2+)/Col I-coating group, respectively, promoted the proliferation and differentiation of osteoblasts, especially 10 mM Mg(2+)/Col I-coating group. We detected the mRNA expression of osteogenic-related genes (Runx2, ALP and OCN, OPN and BMP-2) and the protein expression of signaling pathway (integrin α2, integrin β1, FAK and ERK1/2), these results indicated that 10 mM Mg(2+)/Col I coating play an critical role in up-regulating the MC3T3-E1 cells activity. The potential mechanisms of this specific performance may be through activating via integrin α2β1-FAK-ERK1/2 protein-coupled receptor pathway.