3 Phases of Wound Healing
After a hair transplant, the wounds in the transplanted area typically go through several stages of healing. Initially, there may be some redness and scabbing as the body starts the healing process. Over the first few days to weeks, the scabs gradually fall off, revealing the newly transplanted hair follicles. The healing process continues over the following months as the hair grows and the skin fully recovers, resulting in a natural and seamless appearance. It's essential for patients to follow post-operative care instructions carefully to support optimal healing and hair growth.
Once a hole is made in the recipient area, wound repair starts immediately. Three phases are found: inflammatory, proliferative, and revascularization.
Inflammatory phase
Characterized by clot formation, deposition of fibrin, and an influx of inflammatory cells in the wound.
Proliferative phase
Fibroblasts and epithelial cells migrate to repopulate the wound. Wound contracture and epithelization occurred during this interval. Multiple cytokine growth factors (PDGF, TAGF, TBGF, EGF, and VEGF) increased in the wound during the inflammatory and proliferative phases.
Growth Factors
Growth factors are the engines or modulating factors that drive wounds to heal. Growth factor activity includes the following:
• The transforming alpha growth factor(TGFA) appears on day 1
• The rest of the growth factors appear on day 3
• Day 7 to 21 show slight to moderate activity of all the growth factors
• Day 28 only epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) are present
These growth factors play key roles in initiating and sustaining the phases of tissue repair. They ultimately diffuse or disperse from the wound site to be degraded by inhibitory proteases. Specialized fibroblasts and growth factors from the dermal papilla also play a key role in the control and induction of the normal follicular growth cycle.
Revascularization
After the graft is placed in the recipient site, a “survival” process occurs. Three phases of revascularization:
Stage I Plasmatic imbibition
1–3 days post-op, during which the graft absorbs plasma from the recipient site.
Stage II Primary inosculation
3–7 days post-op, during which early revascularization occurs and connections form between the hair graft and recipient site.
Stage III Secondary inosculation
Day 7, during which there are further changes in the blood vessels (including lymphatics) with coiled vessels extending deeply into the dermal papilla and with budding around the follicular implant. These changes take place simultaneously with the increase in inflammatory cells and growth factors.
