Porous CDHA microspheres laden brushite-based injectable bone substitutes for improved bone regeneration

Porous CDHA microspheres were incorporated into innovative injectable calcium phosphate cement (CPC) to enhance the rate of degradation and bioactivity of bone regeneration. With varying content of CDHA microspheres, the final setting time varied between 12 and 17 min, which is adequate for surgeons to accomplish the implantation. Compressive strength ranged between 6 and 8 MPa, until the addition of porous CDHA microsphere into CPC reached 20 vol %, but decreased dramatically after 30 vol % addition. Therefore, CPC with 20 vol % addition of porous CDHA microspheres was found appropriate for in vitro degradation and cytocompatibility studies. Histological assessment identified new bone formation around the injected bone substitute without significant inflammatory reactions. In vivo analysis of rat femoral defects revealed a threefold higher bone formation in CPC/CDHA 20 vol % than in CPC, due to the more cell migration and penetration into CPC by the existence of porous CDHA microspheres. Based on the promising results obtained, this novel injectable bone substitute may be useful in bone regeneration.