Preparation of bioactive β-tricalcium phosphate microspheres as bone graft substitute materials

In this study, β-tricalcium phosphate (Ca₃PO₄, β-TCP) microspheres with different diameters were fabricated via a solid-in-oil-in-water (S/O/W) emulsion method. After soaking in simulated body fluid (SBF), the fabricated β-TCP microspheres were fully covered with a new bone-like apatite layer; subsequent analysis suggested that the microspheres have excellent bioactivity properties, specifically in inducing apatite deposition. The calcium release profiles of the microspheres were tested in pH7.4 Tris-HCl buffer, and results demonstrated that the Ca²⁺ continually released from microspheres during the two-week test period. We then co-cultured bone marrow stem cells (BMSCs) in vitro with β-TCP microspheres, and performed SEM and confocal microscope analyses to find that β-TCP microspheres efficiently promoted BMSC attachment and bone-related gene expression. The co-cultured BMSCs and microspheres were successfully implanted subcutaneously into nude mice for 8weeks. The H&E neo-tissue staining results showed that abundant new bone-like structures had formed between the β-TCP microspheres, implying that β-TCP microspheres used as a cell carrier and bone graft substitute material show highly promising potential application for irregular-shaped bone defect regeneration.