Extracellular Matrix (ECM)
The complex network of proteins and carbohydrates outside cells that provides structural support, regulates cell behaviour, and stores growth factors. The ECM includes collagens, elastin, fibronectin, and proteoglycans. ECM production and remodelling are central to tissue repair processes.
Technical Context
The ECM is a complex network of: structural proteins (collagens — providing tensile strength; elastin — providing elasticity), glycosaminoglycans (GAGs: hyaluronic acid, chondroitin sulphate, heparan sulphate — hydrated gel that resists compression), proteoglycans (protein-GAG conjugates: aggrecan, decorin, perlecan — providing compressive resistance and growth factor sequestration), adhesive glycoproteins (fibronectin — cell adhesion scaffold during wound healing; laminin — basement membrane component; vitronectin — cell attachment), and matricellular proteins (thrombospondins, tenascins, osteopontin — modulating cell-matrix interactions). The ECM is not merely structural — it actively regulates cell behaviour through: integrin-mediated mechanotransduction, growth factor sequestration and release, and degradation fragment signalling (matrikines). ECM composition varies dramatically between tissues (bone, cartilage, skin, tendon) and changes during wound healing.