Chondrocyter

Chondrocyter, or chondrocytes, are the sole resident cells in cartilage. They originate from mesenchymal stem cells and reside in lacunae within a specialized extracellular matrix. In adults, most chondrocytes are quiescent and rely on diffusion for nutrient supply due to the avascular nature of cartilage.

Cartilage consists of three main types—hyaline, fibrocartilage, and elastic cartilage—each with distinct matrix composition. Chondrocytes synthesize and maintain the extracellular matrix, primarily type II collagen and aggrecan in hyaline cartilage. They can form isogenous groups when they divide during development or repair.

Development and growth: In endochondral ossification, chondrocytes progress from resting to proliferating to hypertrophic zones in growth plates, where their maturation guides bone formation. In mature cartilage, chondrocytes maintain matrix and coordinate remodeling, though activity is limited.

Function and regulation: Chondrocyte metabolism is influenced by mechanical load, oxygen tension, and soluble factors such as TGF-β, BMPs, and IGF-1. They produce matrix-degrading enzymes under certain conditions, balancing synthesis and breakdown.

Clinical relevance: Cartilage has limited regenerative capacity. Injury and diseases like osteoarthritis involve chondrocyte dysfunction and matrix degradation by enzymes such as MMPs and ADAMTS. Therapeutic approaches include cell-based therapies like autologous chondrocyte implantation and tissue engineering strategies.