When I begin a discussion on the phases of wound healing I always think of the analogy of dominos falling. In the traditional surgical model of wound healing, much like in a falling cascade of dominoes, if everything doesn’t happen in an orderly and expected manner the whole process fails. So much like dominoes each phase much happen in a specific and orderly succession.

The first domino to fall in a healing wound is that of hemostasis. The phases begin with some type of incision or trauma that exposes the extracellular matrix protein to platelets. Platelets respond by degranulation leading to 2 major effects: hemostasis and vasoconstriction. The purposes is to lead to clotting and set-up the next phase of the cascade inflammation. The high points of the first phases are listed below. Not every mediator is listed but the major players in the phase are identified.

Hemostasis

• Triggered by injury
• Platelets are activated to aggregate by exposure to collagen/ECM
• Clotting factors released

Major mediators of hemostatasis

• Platelet derived growth factor (PDGF)
  • Cellular division of fibroblasts
  • Blood vessel formation
• Transforming growth factor beta (TGFβ)
• Fibroblast growth factor-2
  • Promotes endotheilal proliferation and organization
  • Leads to Neoangiogensis

Major mediators of vasoconstriction

• Thromboxane A2
• Prostaglandin 2-α