Phosphorylated Chitin Increased Bone Formation when Implanted into Rat Calvaria with the Ti-device

BACKGROUND Previously we found that a group of phosphorylated proteins (SBLINGs) in bone binds with Ti-device, and increases the early bone formation around the Ti-implants remarkably. From these results, we explained the biochemical mechanism of a strong bond between living bone and Ti, which Brånemark had discovered. For the clinical application of our findings, we need a large amount of these proteins or their substitutes. OBJECTIVE:We wanted to create a new molecule that equips with essential functions of SIBLINGs, Ti-binding, and bone enhancement around the Ti implant. METHODS We chemically phosphorylated chitin and obtained a soluble form of phosphorylated chitin (P-chitin). In this solution, we immersed the Ti-devices of web-form (TW) which we have previously developed and obtained the P-chitin coated TWs. Then we tested the P-chitin coated TWs for their calcification ability in vitro, and bone enhancing ability in vivo, by implanting them into rat calvaria. We compared the P-chitin coated TW and the non-coated TW in regard to their calcification and bone enhancing abilities. RESULTS Ti-devices coated with phosphorylated-chitin induced ten times higher calcification in vitro at 20 days, and four times more elevated amount of bone formation in vivo at two weeks than the uncoated Ti-device. CONCLUSIONS We concluded that phosphorylated chitin could be a partial substitute of bone SUBLING proteins and clinically applicable to accelerate bone formation around the Ti implants, thereby achieving the strong bond between living bone and Ti. ABBREVIATIONS SIBLING, small integrin-binding ligand, n-linked glycoprotein; PBS, phosphate-buffered saline; P-chitin, phosphorylated chitin; TW, Ti-device of web-form.