Chondrocyte apoptosis in development, aging and disease.

There is increasing evidence that chondrocyte apoptosis plays an important role in cartilage development, aging and disease. A variety of morphological and biochemical studies have identified apoptotic chondrocytes in both growth plate and articular cartilage of a variety of species. In addition, there is an ever increasing list of diverse stimuli that can induce chondrocyte apoptosis in vitro. A feedback loop regulating chondrocyte apoptosis in the growth plate has been described that includes Indian Hedgehog, parathyroid hormone-related protein and Bcl-2. The molecular mechanism regulating apoptosis in articular cartilage is still under investigation. Future studies should elucidate more fully how abnormal regulation of chondrocyte apoptosis may contribute to the development of chondrodysplasias and chondrosarcomas. Also, it will be of importance to define the relationship between chondrocyte apoptosis and the regulation of chondrocyte-specific gene expression.