extracellularmatrix

The extracellular matrix (ECM) is a complex and dynamic network of macromolecules that occupies the space outside cells. It is composed mainly of fibrous proteins such as collagen and elastin, adhesive glycoproteins like fibronectin and laminin, and specialized carbohydrate-rich molecules including proteoglycans and glycosaminoglycans. A distinct form, the basement membrane, underlies epithelia and endothelium and is rich in laminin, type IV collagen, and heparan sulfate proteoglycans.

The ECM provides structural support and mechanical properties to tissues while regulating cell behavior. It acts as a reservoir for growth factors, modulates cell adhesion, migration, proliferation, and differentiation, and transmits mechanical signals to cells via receptors such as integrins. ECM composition and stiffness vary by tissue and developmental stage, influencing processes from organogenesis to wound healing. Remodeling of the ECM, mediated by enzymes such as matrix metalloproteinases, is a normal part of growth and repair but can contribute to disease when dysregulated.

In health, ECM homeostasis supports tissue integrity and function. Alterations in ECM composition or cross-linking are associated with aging, fibrosis, cancer progression, and degenerative diseases. The ECM is also exploited in research and medicine; decellularized matrices serve as scaffolds for tissue engineering, and synthetic or modified ECM components are used to study cell–matrix interactions and develop regenerative therapies.