Injectable scaffolds held great promise for the reconstruction of bone defects. We prepared an injectable composite named PTC by combining TCP/chitosan (TC) with platelet-rich plasma (PRP). The objective of this study was to investigate the composite's mechanical and biological properties. First, we found that the introduction of PRP in TC showed no adverse effect on mechanical strength and that there were no significant differences in compressive strength between PTC and TC (P>0.05). In cell culture experiments, both cell count and alkaline phosphatase (ALP) activity measurements of PTC were higher than those of TC. The high levels of Cbfa1 and TGF-beta were detected early in PTC-induced MSCs by reverse transcriptase polymerase chain reaction. Bone formation following expression of collagen type I, osteocalcin, osteonectin and calcium nodules was also observed in PRP-induced MSCs. Finally, this composite was injected into the tibial bone defect in a goat model, and its ability to induce bone regeneration was observed. Sixteen weeks after the implantation of this composite, the tibial defects had completely recuperated, with significantly better formation of mature bone and less residual material than in the control. These results demonstrate that our composite, with its concomitant mechanical strength, biocompatibility, and osteoinductive properties, has significant potential as an injectable material for the treatment of bone defects.
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