Reconstruction of calvarial defect using a tricalcium phosphate-oligomeric proanthocyanidins cross-linked gelatin composite

A biodegradable GTP composite which was composed of oligomeric proanthocyanidins (OPCs) cross-linked gelatin mixed with tricalcium phosphate was developed as a bone substitute. The subcutaneous implantation in rats was examined to determine the in vivo degradation and biocompatibility of the GTP composites with various cross-linking densities. Experimental results indicated that the rate of in vivo degradation was markedly attenuated as the concentration of OPCs increased above 5.0 wt%. Furthermore, this study examined the biological response of rabbit calvarial bone to GTP composite to evaluate its potential for use as an osteoconductive bone substitute. Bone defects (10 mm in diameter) in New Zealand white rabbits were filled with the GTP composite. The de-protenized bovine cancellous bone matrix was employed as the control material. The results of radiographic analyses demonstrated obviously greater new bone ingrowth in the GTP composite than in the de-proteinized bovine bone at the same implantation time. Progressive replacement of the GTP composite by new bone proceeded by a combination of osteoconduction and biodegradation. The biodegradable GTP composite thus has great potential for improving bone repair.