Phosphorylation of porcine bone collagen peptide to improve its calcium chelating capacity and its effect on promoting the proliferation, differentiation and mineralization of osteoblastic MC3T3-E1 cells

In this study, porcine bone collagen peptide (CP) was phosphorylated with sodium tripoly phosphate (STP) in order to improve its calcium binding capacity and osteogenic activity. Firstly, the phosphorylation process were optimized by an orthogonal experiment. Then, the effects of CP, phosphorylated CP (PCP), CP-calcium chelate (CP-Ca) and PCP-Ca on proliferation, differentiation and mineralization of MC3T3-E1 cells were investigated. The results showed that all of the CP, PCP, CP-Ca and PCP-Ca could enhance the proliferation, differentiation and mineralization of MC3T3-E1 cells by increasing the mRNA expression levels of alkaline phosphatase (ALP), Runt-related transcription factor-2 (Runx2), osteocalcin (OCN), osteopontin (OPN) and collagen type I (Col I), as well as the protein expression levels of Runx2 and beta-Catenin. Especially, PCP-Ca had the greatest and significant effect on mineralization of MC3T3-E1 cells (P < 0.05). These results suggested that phosphorylation is a promising method to improve the calcium binding capacity and osteogenic activity of collagen peptides.