OP-1 (BMP-7) stimulates osteoprogenitor cell differentiation in the presence of polymethylmethacrylate particles.

Polymethylmethacrylate (PMMA) particles have been shown to inhibit the differentiation, proliferation, and mineralization of osteoprogenitor cells in vitro. In this study, we investigated the effects of OP-1 (BMP-7) on the osteogenesis of MC3T3-E1 osteoprogenitor cells exposed to PMMA particles in vitro. MC3T3-E1 cells challenged with PMMA particles on the 1st day of differentiation in osteogenic culture showed a significant dose-dependent decrease in mineralization and alkaline phosphatase expression over a 20-day culture period. Exposure of these cells to OP-1 (200 ng/mL) during days 1-4, 1-20, and 4-20 in the presence of PMMA particles resulted in significant increases in mineralization and alkaline phosphatase expression at all particle doses. Addition of OP-1 to MC3T3-E1 cultures challenged with PMMA particles on the 4th day of differentiation in osteogenic media also resulted in significant increases in mineralization and alkaline phosphatase expression. This study has shown that OP-1 stimulates osteogenesis in MC3T3-E1 osteoprogenitor cells that have been inhibited by PMMA particles. Local administration of OP-1 to the site of osteolysis may be a potential adjunctive therapy to reverse the bone destruction due to wear particles.