wound healing

Introduction

Restoration of integrity to an injured tissue.

Pathology

3 phases* of wound healing:

• initial tensile strength
  • hemorrhage into tissue
  • formation of a fibrin clot
  • fibronectin in extravasated plasma is cross-linked to extracellular matrix components (fibrin, collagen) by transglutaminases
• remodelling
  • phagocyte (neutrophil, macrophage) recruitment
  • proteolysis & phagocytosis
  • temporary matrix formation from blood proteins
    • proteoglycans
    • glycoproteins
    • type 3 collagen
    • fibronectin
• definitive scar
  • proliferation
    • fibroblasts
    • endothelial cells
    • smooth muscle
  • granulation tissue
  • wound contraction
  • definitive matrix
    • type 1 collagen

* ref suggests 4 phases, hemeostasis, inflammatory, proliferative, & maturation

2 forms of healing

• healing by primary intention
  • wounds with apposed edges of healthy tissue
  • minimal tissue loss
  • requires minimal cell proliferation & neovascularization
  • small scar
  • for clean wounds
• healing by secondary intention
  • wounds with separated edges of healthy tissue
  • gouged wound, significant tissue loss, contaminated wound
  • requires granulation tissue to heal
    • wound contraction
    • cell proliferation
    • neovasculatization
  • wound re-epithelialized from margins
  • collagen fibers in granulation tissue
  • granulation tissue eventually resorbed & replaced by scar tissue

More general terms

• healing

More specific terms

• impaired wound healing; impaired tissue repair