Signaling pathways in cartilage repair

Abstract

In adult healthy cartilage, chondrocytes are in a quiescent phase characterized by a fine balance between anabolic and catabolic activities. In ageing, degenerative joint diseases and traumatic injuries of cartilage, a loss of homeostatic conditions and an up-regulation of catabolic pathways occur. Since cartilage differentiation and maintenance of homeostasis are finely tuned by a complex network of signaling molecules and biophysical factors, shedding light on these mechanisms appears to be extremely relevant for both the identification of pathogenic key factors, as specific therapeutic targets, and the development of biological approaches for cartilage regeneration. This review will focus on the main signaling pathways that can activate cellular and molecular processes, regulating the functional behavior of cartilage in both physiological and pathological conditions. These networks may be relevant in the crosstalk among joint compartments and increased knowledge in this field may lead to the development of more effective strategies for inducing cartilage repair.

Figure 1.

Schematic overview of signaling cross-talk among transforming growth factor-β (TGF-β), bone morphogenetic proteins (BMPs), hypoxia-related factors (HIF), Wnt/β-catenin, nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and Indian hedgehog (Ihh) pathways.