chondrogenese

Chondrogenese, or chondrogenesis, is the developmental process by which cartilage is formed from mesenchymal tissue. It occurs during embryogenesis and continues in postnatal life during growth and repair. The process begins with condensation of mesenchymal cells, followed by differentiation into chondroblasts that secrete the cartilaginous extracellular matrix rich in collagen type II and proteoglycans, producing hyaline cartilage. In many regions the cartilage anlage is surrounded by a perichondrium, which provides progenitor cells for appositional growth.

Chondroblasts mature into chondrocytes within lacunae, and the cartilage template expands and organizes into cartilage tissue. In endochondral ossification, this cartilage model is later invaded by blood vessels and replaced by bone, whereas articular cartilage and growth plate cartilage persist as mature cartilage tissue. Cartilage formed by chondrogenesis is typically avascular and relies on diffusion for nutrient delivery.

Chondrogenesis is tightly regulated by transcription factors and signaling pathways. SOX9 is the master regulator of chondrogenic differentiation, driving expression of collagen type II (COL2A1) and aggrecan. Other factors include SOX5, SOX6, TGF-β, BMPs, and WNT signaling, with Indian hedgehog (IHH) and PTHrP shaping chondrocyte maturation in growth plates.

Clinical relevance includes developmental chondrodysplasias such as achondroplasia caused by FGFR3 mutations, and cartilage degeneration in osteoarthritis. In regenerative medicine, directed chondrogenesis from mesenchymal stem cells or pluripotent stem cells is investigated to repair damaged cartilage and engineer tissue constructs.