Basic calcium phosphate crystals stimulate cell proliferation and collagenase message accumulation in cultured adult articular chondrocytes

Objective: To investigate BCP (basic calcium phosphate) crystal-stimulated mitogenesis and collagenase gene transcription in primary cultures of porcine chondrocytes. Methods. The role of protein kinases in BCP crystal-stimulated DNA synthesis was investigated using thymidine incorporation, kinase inhibitors, and protein kinase C (PKC) assays. Northern blot analysis was used to determine the levels of collagenase c-fos and c-jun message. Results. BCP crystals stimulated chondrocyte proliferation in a PKC-dependent manner. Increased levels of collagenase message were preceded by an increased accumulation of c-fos, but not c-jun. Conclusion. BCP crystals could contribute to the abnormal chondrocyte proliferation and collagenase secretion observed in some rheumatic diseases.