process

Wound healing

The physiological process of wound healing is traditionally divided into four phases: haemostasis, inflammation, proliferation, and maturation or remodelling. These phases are orchestrated by a subtle interplay of cellular and humoral factors [4]. Haemostasis occurs within an hour after injury and is characterized by vasoconstriction and clotting. Platelets not only initiate the clotting cascade but also secrete growth factors and cytokines which initiate healing. The subsequent inflammation phase takes up to seven days and is mediated through neutrophil granulocytes which prevent bacterial contamination and cleanse the wound from cell debris. Monocytes are attracted to the wound by chemotactic factors and differentiate into wound macrophages. The latter not only remove bacteria and nonviable tissue by phagocytosis but also release various growth factors required to stimulate fibroplasia and angiogenesis, thereby providing the basis for the formation of the provisional extracellular matrix (ECM). The proliferation phase is initiated at day 2 after injury and takes up to 20 days. This phase is primarily characterized by tissue granulation and formation of new blood vessels (angiogenesis). The angiogenic process involves growth factors such as platelet-derived growth factor (PDGF), macrophage angiogenesis factor, and angiotensin. Concomitant epithelialisation is then initiated to cover the granulation tissue with a cellular barrier. The last phase involving extensive tissue remodelling lasts from one week to six months after injury. During that phase the provisional wound matrix is replaced with proteoglycan and collagen molecules which readily become organised into thicker bundles resulting in stronger but more rigid scar tissue.

Ref:
Tsourdi E, Barthel A, Rietzsch H, Reichel A, Bornstein SR. Current aspects in the pathophysiology and treatment of chronic wounds in diabetes mellitus. Biomed Res Int. 2013;2013:385641. doi: 10.1155/2013/385641. Epub 2013 Apr 7. PMID: 23653894; PMCID: PMC3638655.

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Added on May 18, 2022 by Barbara Van De Keer
Edited on Oct 8, 2022 by Barbara Van De Keer

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