Hierarchically porous calcium phosphate scaffold with degradable PLGA microsphere network

Calcium phosphate cement (CPC) is widely used in orthopedics, dentistry and spine surgery because of its excellent biocompatibility, osteoconductivity, arbitrary shaping and self-setting ability. However, slow degradation rate of CPC decreases its bone regeneration efficacy. Herein, poly (lactic co-glycolic acid) microspheres (PLGAm) and wollastonite (WS) were mixed with CPC powder to prepare CPC composite pastes, and then the composite pastes were perfused into poly (lactic co-glycolic acid) network (PLGAnw) to construct composite bone repair materials. The degradation of PLGAnw generated interconnected macropores with the short side of about 468 μm along horizontal axis and the long side of about 785 μm along longitudinal axis, while PLGAm degradation generated isolated or partially connected relative smaller spherical macropores with the size range of 53–106 μm and 106–150 μm, respectively, which was same with PLGAm; in addition, CPC formed micro/nano pores after hydration, thus constructing in-situ hierarchically porous CPC composite scaffolds. Meanwhile, PLGAnw and PLGAm also significantly promoted the degradation of CPC due to the release of acidic by-products. Therefore, the introduction of PLGA network and microspheres not only can evidently accelerate degradation of CPC, but also in-situ form connected macropores and hierarchically porous after their degradation, which are expected to improve bone repair effect of CPC.