Osteoconductive and Bioresorbable Composites Based on Poly(L,L-lactide) and Pseudowollastonite: From Synthesis and Interfacial Compatibilization to In Vitro Bioactivity and In Vivo Osseointegration Studies

This contribution reports on the elaboration of novel bioresorbable composites consisting of pseudowollastonite (psW) (a silicate-based polycrystalline ceramic (alpha-CaSiO3)) and poly(L,L-lactide) as a valuable polymeric candidate in bone-guided regeneration. These composites were prepared by direct melt-blending to avoid the use of organic solvents harmful for biomedical applications. Amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymers synthesized by ring-opening polymerization were added to psW-based composites to modulate the bioactivity of the composites. The bioactivity of the composites was first evaluated by monitoring the release of bioactive Ca2+ and (SiO4)(4-) ions as well as the concomitant formation of hydroxyapatite on the material surface after soaking them in physiological fluid. Subsequently, the composites were studied in vitro to evaluate their cytotoxicity in the presence of SaOS-2 osteoblastic cells and in vivo to assess their osteoconductivity in an orthotopic rat tibia model. This study provides a first insight into the use of direct melt-blended psW-poly(L,L-lactide) composites for bone-regeneration applications.