Anorganic Bone Mineral Coated with Tetra-Cell Adhesion Molecule Enhances Bone Formation in Rabbit Calvarial Defects

Abstract

This study was performed to evaluate the effect of anorganic bone mineral (ABM) coated with Tetra-Cell Adhesion Molecule (T-CAM) for bone formation in rabbit calvarial defects and compare the capability of bone formation in ABM coated with T-CAM (ABM/T-CAM) to that in commercially available ABM coated with a synthetic peptide (P-15) which mimics the cell-binding domain of type I collagen, PepGen P-15TM. T-CAM composed of four cell adhesion molecules (RGD, PHSRN, EPDIM, and YH) was synthesized and ABM/T-CAM were prepared by absorbing T-CAM on ABM (OsteoGraf/N-300; Densply Friadent Ceramed Corp., USA). Two 9-mm diameter, full-thickness calvarial defects were made in each rabbit parietal bone and sixteen adult male rabbits were used in this experiment. The defects were reconstructed according to four treatment groups: unfilled, BM-grafted, PepGen P-15TM-grafted, and ABM/T-CAM-grafted. The animals were sacrificed at 2 and 4 weeks after surgery for histologic and histomorphometric evaluation. An active new bone formation were observed in the defects of ABM/T-CAM and PepGen P-15TM grafted groups at 2 and 4 weeks of healing in histologic observation. The results of histomorphometric analysis revealed higher new bone formation in ABM/T-CAM-grafted (14.62±0.6% at 2 weeks, 15.33±2.4% at 4 weeks) and PepGen P-15TM-grafted (12.46±1.0% at 2 weeks, 18.14±1.7% at 4 weeks) groups than in unfilled control (7.03±2.3% at 2 weeks, 8.71±3.4% at 4 weeks) and ABMgrafted (6.59±1.7% at 2 weeks, 9.25±0.8% at 4 weeks) groups at 2 and 4 weeks of healing with statistical significance (P<0.01). The results of this study indicated that the immobilizing T-CAM on ABM enhances the capability of bone substitutes to serve as an effective habitat for bone forming cells in vivo. In conclusion, we suggested that this composite graft material, ABM/T-CAM may be served as an effective tissue-engineered bone graft material in osseous reconstructive surgery.