In vitro and in vivo analysis of the biocompatibility of two novel and injectable calcium phosphate cements

Calcium phosphate cements (CPCs) have been widely used as bone graft substitutes for many years. The aim of this study was to evaluate the biocompatibility of two novel injectable, bioactive cements: β-tricalcium phosphate (β-TCP)/CPC and chitosan microsphere/CPC in vitro and in vivo. This was accomplished by culturing mouse pre-osteoblastic cells (MC3T3-E1) on discs and pastes of CPCs. Cell growth, adhesion, proliferation and differentiation were assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and alkaline phosphatase assays as well as by scanning electron microscopy and fluorescence. The effect of CPC paste curing was also evaluated. Implantation of two materials into the muscle tissue of rabbits was also studied and evaluated by histological analysis. Cell analysis indicated good biocompatibility in vitro. The fluorescence assay suggested that the cured material discs had no obvious effect on cell growth, while the curing process did. Histological examination showed no inflammatory cell infiltration into soft tissue. These data suggest that β-TCP/CPC and chitosan microsphere/CPC composites may be promising injectable material for bone tissue engineering.