Effects of Polypropylene Carbonate/Poly(d,l-lactic) Acid/Tricalcium Phosphate Elastic Composites on Improving Osteoblast Maturation

Bone tissue engineering utilizing biomaterials to improve osteoblast growth has provided de novo consideration for therapy of bone diseases. Polypropylene carbonate (PPC) is a polymer with a low glass transition temperature but high elasticity. In this study, we developed a new PPC-derived composite by mixing poly-lactic acid (PLA) and tricalcium phosphate (TCP), called PPC/PLA/TCP elastic (PPTE) scaffolds. We also evaluated the beneficial effects of PPTE composites on osteoblast growth and maturation and the possible mechanisms. Compared to PPC polymers, PPTE composites had similar pore sizes and porosities but possessed better hydrophilic surface structures. Biological evaluations further revealed that PPTE composites attracted adhesion of mouse osteoblasts, and these bone cells extended along the porous scaffolds to produce accurate fibroblast-like morphologies. In parallel, seeding mouse osteoblasts onto PPTE composites time-dependently increased cell growth. Sequentially, PPTE composites augmented DNA replication and cell proliferation. Consequently, PPTE composites significantly improved osteoblast mineralization. As to the mechanism, treatment with PPTE composites induced osteopontin (OPN) mRNA and protein expression and alkaline phosphatase activity. Taken together, this study showed that PPTE composites with porous and hydrophilic surfaces can stimulate osteoblast adhesion, proliferation, and maturation through an OPN-dependent mechanism. Therefore, the de novo PPTE scaffolds may have biomaterial potential for bone regeneration.