Question

Give a short and concise answer. What is an extracellular matrix, and what role does it play in wounds and healing of wounds?

Answer 1

Extracellular matrix (ECM) is a complex mixture of extracellular molecules secreted by cells to provide structural support along with biochemical functions. These extracellular molecules form a mesh work which is made up of of proteoglycans (a protein core protein bonded to mucopolysaccharide groups), fibrous proteins, minerals and water.

Extracellular Matrix and Wound Healing

When there is a cut, the collagen fibrils and other damaged proteins signals for blood clot formation. Collagen through integrins signals myofibroblasts and keratinocytes for wound contraction. Later ECM components fibrin and fibronectin secrete cytokines and other growth factors and forms a temporary matrix acts as a scaffold acting as wound bed, initiating the repairing process.

Integrin binds to fibronectin and vitronectin of endothelial cells, for angiogenesis, by activating vascular endothelial growth factor (VEGF).

Leukocytes enter the extracellular space and bind to ECM through integrins. ECM proteins activate monocytes/macrophages which in turn produce various cytokines and chemoattractants for fibroblasts.   

The growth factors released by macrophages stimulate angiogenesis, synthesis of collagen, and proliferation of fibroblasts. The fibroblasts develops into myofibroblasts stimulated by ECM proteins and growth factors. Myofibroblasts signals collagen, vitronectin, and other proteins for wound contraction. Later collagen bundles are formed that lend strength to the tissue.