Early Vs Cellular Phase
As mentioned above, wound healing is classically divided into hemostasis, inflammation, proliferation, and remodeling. Although a useful construct, this model employs considerable overlapping among individual phases. Recently, a complementary model has been described, such that the many elements of wound healing are more-clearly delineated. The importance of this new model becomes more apparent through its utility in the fields of regenerative medicine and tissue engineering (see Research and development section below). In this construct, the process of wound healing is divided into major two phases: early phase and cellular phase:
The early phase, which begins immediately following skin injury, involves cascading molecular and cellular events leading to hemostasis and formation of an early, makeshift extracellular matrix—providing structural support for cellular attachment and subsequent cellular proliferation.
The cellular phase follows the early phase, and involves several types of cells working together to mount an inflammatory response, synthesize granulation tissue, and restore the epithelial layer. Subdivisions of the cellular phase are: Macrophages and inflammatory components (within 1–2 days), Epithelial-mesenchymal interaction: re-epithelialization (phenotype change within hours, migration begins on day 1 or 2, Fibroblasts and myofibroblasts: progressive alignment, collagen production, and matrix contraction (between day 4 day 14), Endothelial cells and angiogenesis (begins on day 4), Dermal matrix: elements of fabrication (begins on day 4, lasting 2 weeks) and alteration/remodeling (begins after week 2, lasting weeks to months—depending on wound size.).
Read more about this topic: Wound Healing
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