Stage 1: Haemostasis⁷

When an injury damages the blood vessels, the body’s first reaction is to stop the flow of blood, a process called ‘haemostasis’. The body activates platelets and releases growth factors. The release of these growth factors starts the healing process.⁶

Stage 2: The Inflammatory response

The second stage is divided into an early and a late inflammatory response.⁷

• In the early inflammatory response, neutrophils (a type of white blood cell) are present for two to five days. Neutrophils play an important role in the healing process. They kill local bacteria, which helps to break down dead tissue. They also release active antimicrobial substances and proteases (an enzyme that catalyses proteolysis), which start debridement (i.e. the removal of damaged tissue).
  
  
• In the late inflammatory response, approximately three days after the injury, monocytes (another type of white blood cell) appear. Monocytes are important because they mature into macrophages, large cells that eat bacteria, dead neutrophils and damaged tissue. They also secrete growth factors, chemokines and cytokines. In this way, macrophages play an important role in wound healing and fighting off infection.

Stage 3: Proliferation

During this stage, macrophages produce a variety of substances that cause the body to produce new tissue and blood vessels – a process called angiogenesis. The new tissue then fills the wound bed.⁶ In the final stage of proliferation, the wound edges slowly start to contract and move closer together.

Stage 4: Re-modelling

Re-modelling starts already in the proliferation stage and continues for an extended period of time. Collagen plays an important role in this stage of the healing process. Throughout this stage, the body simultaneously produces and breaks down collagen. It does this to maintain a balance between the need for tensile strength and the re-modelling of new tissue. This balance is what determines the scar tissue’s final quality and appearance.⁷