Casein phosphopeptides–vaterite calcium carbonate enhance cytocompatibility and osteoinductivity of poly(l‐lactic acid)

Although calcium carbonate has been proved to be effective in neutralizing the acid degradation products of poly(l‐lactic acid) (PLLA), it has no osteoinductivity. In this study, casein phosphopeptides (CPPs)‐containing CaCO₃ vaterite were synthesized by fast precipitation in an aqueous solution of CaCl₂, Na₂CO₃, and 2 mg/ml of CPPs. CaCO₃–PLLA composite membranes (P‐vaterite–CPP) were prepared (CaCO₃/PLLA =1:2) and exhibited uniform structure and increased hydrophilicity. These composite membranes enhanced hydroxyapatite formation after incubated in simulated body fluid at 37°C for 7 days. The P‐vaterite–CPP membranes promoted human bone marrow stromal cells (hBMSCs) proliferation 4 and 7 days after seeding. Scanning electron microscope images of hBMSCs on the composite membranes exhibited a polygonal and unevenly spreading morphology. Immunofluorescent staining of cytoskeleton and focal adhesion showed that hBMSCs had more stress fibers and were more spreading, indicating a good cell adhesion on the CPPs‐containing composite membranes. Osteogenesis related genes (alkaline phosphatase, collagen type, osteocalcin, and osteopontin) expressions were significantly higher on the CPPs‐containing membranes than those on the CPPs‐free membranes (P < 0.05). It can be concluded that the addition of CPPs induces vaterite formation and thus improve cytocompatibility and osteoinductivity of PLLA. POLYM. COMPOS., 36:1213–1223, 2015. © 2014 Society of Plastics Engineers