Bone regeneration by freeze-dried composite of octacalcium phosphate collagen and teriparatide

Abstract

Objective: Octacalcium phosphate (OCP) and collagen (col) composite (OCPcol) demonstrated superior bone regeneration properties, and its commercialization appears to be forthcoming. As a practical medical material for new combination products, we developed a freeze-dried composite with OCPcol and teriparatide (TPTD) (OCPcolTPTDf), and investigated its bone regenerative properties. Materials and Methods: A disk of OCPcol was made by mixing OCP granules and atelocollagen for medical use. Then, OCPcolTPTDf was prepared by impregnation of the OCPcol disk with 1.0 or 0.1 µg of TPTD solution (OCPcolTPTDf 1.0 and OCPcolTPTDf 0.1, respectively) followed by lyophilization. In vitro release profiles of TPTD from OCPcolTPTDf were determined using an enzyme-linked immunosorbent assay. Implantation of OCPcolTPTDf or OCPcol was carried out for a rat critical-sized calvarial defect. And five defects in each group were collected after 12 weeks of implantation. Results: The retention–release profiles of TPTD from OCPcolTPTDf supported a higher degree of retention of TPTD. Radiographic, histological, and histomorphometric examinations indicated that regenerated bone was filled in most of the defects of the OCPcolTPTDf. Additionally, the OCPcolTPTDf groups showed significantly enhanced bone regeneration compared with the OCPcol group. Conclusions: These results suggested that this newly developed bone regenerative composite could be a practical medical material.