Wound Healing Phases

The four overlapping phases: (1) Haemostasis (seconds to hours): platelet activation, coagulation cascade, fibrin clot formation — the clot provides temporary wound closure and a scaffold for incoming cells, and platelet degranulation releases growth factors (PDGF, TGF-β, EGF) initiating the repair cascade. (2) Inflammation (hours to days 5-7): neutrophil infiltration (peak 24-48h, phagocytose bacteria and debris), followed by monocyte/macrophage infiltration (peak day 3-5, phagocytosis + cytokine/growth factor secretion — macrophages are critical orchestrators of the transition from inflammation to proliferation). (3) Proliferation (days 3-21): fibroblast migration and proliferation, collagen synthesis, angiogenesis (VEGF-driven), granulation tissue formation, and re-epithelialisation (keratinocyte migration from wound edges). (4) Remodelling (weeks to 1-2 years): collagen crosslinking, type III→type I collagen transition, wound contraction (myofibroblasts), and scar maturation. Each phase offers potential intervention points for wound healing peptides.