In Vitro and In Vivo Osteoconductivity of Bone Marrow Stromal Cells in Biomimetic Polycaprolactone/Calcium Phosphate Cement Composites

Biomimetic, macroporous composites of polycaprolactone (PCL) and calcium phosphate cement (CPC) were fabricated and successfully applied as bioscaffolds for in vitro culture of bone marrow stromal cells (BMSCs). These spongy composites could be obtained by simple mixing of PCL and CPC and then removal of sodium chloride particle. The properties of the composites such as morphology, porosity and mechanical modulus were characterized by scanning electron microscopy, Archimedes method and dynamic mechanical analysis. It was found that the incorporation of PCL into CPC could markedly improve the modulus of resulting PCL/CPC composites, yielding an optimal modulus at a PCL/CPC mass ratio of 70/30. These composites were examined by in vitro culture of rat BMSCs into the composites and evaluation of the cellular attachment profile, proliferation and differentiation into osteoblastic phenotypes. Further, osteoconductivity of the composites were investigated in vivo by determining the osteogenesis in nude mouse and rat. The PCL/CPC scaffold at a mass ratio of 70/30 could allow BMSCs for active attachment, proliferation, and osteogenesis in full-thickness, critical-size mandibular in a rat model. Because of improved mechanical modulus and good biocompatibility in vivo, the PCL/CPC 70/30 composite system has high potential for bone implantation.