Articular chondrocytes transduce mechanical signals through the Wnt pathway

Abstract

Since the late 1980s, if not earlier, there has been clear evidence to show that mechanical stimulation of chondrocytes and cartilage can result in matrix synthesis. In 1989, Sah et al. demonstrated that cyclical compression of cartilage explants resulted in incorporation of radiolabels to both collagen and glycosaminoglycan (GAG) fractions.1 Moreover, cyclical tensile stretching of chondrocytes increases collagen and GAG synthesis in primary osteoarthritic (OA) chondrocytes.2 Several additional studies have found that cyclical compression of chondrocytes results in the synthesis of cartilage matrix molecules.3, 4, 5 In contrast, static compression of cartilage explants and chondrocytes appears to result in matrix degradation and inhibition of matrix synthesis.6, 7 These in vitro observations are consistent with several in vivo studies. For example, aged marathon runners have thicker cartilage than aged non-marathoners,8 and increased physical activity levels are associated with fewer OA symptoms.9, 10 However, relatively few mechanisms of chondrocyte mechanotransduction are known.