Restoring articular cartilage: insights from structure, composition and development

Articular cartilage can withstand substantial compressive and shear forces within the joint and also reduces friction during motion. The exceptional mechanical properties of articular cartilage stem from its highly organized extracellular matrix (ECM). The ECM is composed mainly of collagen type II and is pivotal in conferring mechanical durability to the tissue within its proteoglycan-rich matrix. Articular cartilage is prone to injury and degeneration, and current treatments often fail to restore the mechanical function of this tissue. A key challenge is replicating the intricate collagen-proteoglycan network, which is essential for the long-lasting restoration and mechanical durability of the tissue. Understanding articular cartilage development, which arises between late embryonic and early juvenile development, is vital for the creation of durable therapeutic strategies. The development of the articular ECM involves the biosynthesis, fibrillogenesis and self-assembly of the collagen type II network, which, along with proteoglycans and minor ECM components, shapes the architecture of adult articular cartilage. A deeper understanding of these processes could inform biomaterial-based therapies aimed at improving therapeutic outcomes. Emerging biofabrication technologies offer new opportunities to integrate developmental principles into the creation of durable articular cartilage implants. Bridging fundamental biology with innovative engineering offers novel approaches to generating more-durable 3D implants for articular cartilage restoration.