Phases of wound healing

What it is

Wound healing is set out in four stages in order:

1. Hemostasis and coagulation: the blood clot.
2. Inflammation: the scab, with fibroblast, macrophage and blood vessel, and neutrophils marked at this stage.
3. Proliferative and migration: fibroblasts proliferating, with the subcutaneous fat.
4. Remodeling: freshly healed epidermis and freshly healed dermis.

Each stage carries its own work:

• Hemostasis: platelet aggregation, fibrin plug formation, and release of growth factors.
• Inflammation: wound debridement, and cell recruitment of macrophages, neutrophils and monocytes.
• Proliferation: keratinocyte migration, synthesis of extracellular matrix (ECM), angiogenesis, and re-epithelization.
• Remodeling: fibroblasts conversion to myofibroblasts, wound closure with the scar formed and revised, and contraction and tensile strength.

The time runs beneath them: hours for hemostasis, days to weeks for inflammation and proliferation together, and weeks to months for remodeling, so remodeling is the long one.