An investigation of the cytotoxicity and histocompatibility of in situ forming lactic acid based orthopedic biomaterials.

The cytotoxicity and biocompatibility of polymer networks prefabricated from multifunctional lactic acid based oligomers that are being developed for orthopedic applications were assessed through in vitro cytotoxicity analysis and subcutaneous implantation. After 7 and 14 days, no significant difference was observed in the relative viability or alkaline phosphatase activity of primary rat calvarial osteoblasts cultured in the presence or absence of degrading polymer networks, indicating that the degradation products had no detrimental effect on the function or activity of the cultured cells. The tissue response to preformed lactic acid networks implanted in rats consisted of a mild inflammatory response with an increase in fibrous capsule thickness and inflammation correlating with faster degrading polymer compositions. This relatively neutral response is indicative of a biocompatible, degradable polymer that has potential medical applications. Finally, porous scaffolds were implanted subcutaneously in rats, and vascularized fibrous tissue infiltration was highly dependent on the scaffold porosity and architecture. This finding indicates that an in situ forming porous scaffold of this composition may support the infiltration of surrounding vascularized tissue, and thus be applicable to orthopedic treatments of large bone defects.