chondrocyte hypertrophy and osseous overgrowths, and a role for parathyroid hormone-related protein (PTHrP) in inhibiting chondrocytes from hypertrophic diff erentiation during the process of endochondral ossifi

Articular cartilage injuries and osteoarthritis (OA) are commonly encountered in joint diseases. Current treatments aim at generating hyaline-like repair tissue with a stable, permanent chondrocyte phenotype. However, the repair tissue is often accompanied by chondrocyte hypertrophy and bony outgrowths, in particular with respect to bone marrow-eroding techniques [1,2]. Th e progressive abnormal hypertrophy may result in degradation of the matrix, impairing the function of the repair tissue. A role for parathyroid hormone-related protein (PTHrP) in regulating endochondral ossifi cation by inhibit ing chondrocytes from hypertrophy has been demon strated. Moreover, the inhibitory eff ect of PTHrP on expression of hypertrophy-related markers in articular chondrocytes and during chondrogenic diff erentiation of mesenchymal stem cells (MSCs) has been reported by a number of studies [3-7]. Th ose fi ndings indicate that PTHrP has potential for cartilage repair through inhibiting chondrocyte hypertrophy. Th is review presents, compares and discusses the inhibitory function of PTHrP on chondrocyte hypertrophy in articular cartilage and during the process of endochondral ossifi cation, as well as the process of MSC chondrogenic diff erentiation. Moreover, a strategy for using PTHrP for articular cartilage repair is suggested.