TP508 is a 23 amino acid peptide derived from human prothrombin. It helps wound healing in both soft tissues and bones. In our previous study, we have demonstrated that TP508 retains chondrocyte in a less mature differentiation state while expanding the cartilage mass, indicating it may partly help bone healing by expand the cartilage template in the endochondral bone formation stage. In our current study, we want to demonstrate that TP508 also blocks chondrocyte apoptosis. We used rat costochondral growth plate chondrocytes as our model. We first established chelerythrine as an apoptogen in chondrocytes. TP508 is able to block apoptosis caused by chelerythrine. Chelerythrine also causes an increase in NO production, which is known to cause both pathological and physiological apoptosis of chondrocyte, and blocking NO production can in turn block apoptosis caused by them. TP508 is also able to block NO production caused by chelerythrine. Therefore, TP508 may partially block chondrocyte apoptosis by blocking NO production. From all above, we conclude that besides decreasing chondrocyte differentiation, TP508 also blocks their apoptosis, so as to conserve the cartilage template in endochondral bone formation