Fast shaping, biodegradation and microenvironment modulation in bioceramic calcium phosphate cement enhances osteointegration and bone regeneration

Abstract Critical bone defects require repair materials for optimal treatment. The current range of available materials has limitations, including donor availability, rejection, disease transmission, and inadequate filling. Calcium phosphate bone cement (CPC) is a bone repair material, but most CPCs on the mar-ket have two drawbacks: difficulty degrading and prolonged solidification time. The purpose of this study was to develop a CPC that is rapidly moldable and biodegradable, improves the acid‒base mi-croenvironment, and is more suitable for clinical use. This CPC was prepared from β-tricalcium phosphate bioceramics (TCP) and calcium phosphate monohydrate and is designated a bioceramic calcium phosphate bone cement (BCPC). TCP was used as a control to determine the biocompatibil-ity of BCPC and its impact on osteogenesis-related protein activity. The BCPC and TCP implants were placed in the femurs of rabbits, and X-ray/micro-CT images were obtained at weeks 4, 8, and 12 postoperatively. Additionally, samples from the three time points were stained and analyzed for their osteogenic and degradation properties. BCPC submerged in phosphate buffer reached a neutral pH of 6.98 ± 0.02 on Day 3. In vitro tests revealed that BCPC increased alkaline phosphatase and osteo-pontin activities in MC3T3-E1 cells. The X-ray and micro-CT results revealed that BCPC degraded while the TCP volume remained stable. Micro-CT revealed that BCPC degraded by 26.93% and formed 12.89% new bone by week 12. The histological results showed that BCPC had good bio-compatibility and osteointegration ability. BCPC is characterized by rapid solidification and molding and good biocompatibility, and its degradation rate matches the rate of bone regeneration. BCPC could rapidly improve the surrounding pH, providing the foundation for its clinical application.