Wound healing - A literature review

Abstract

Regeneration and tissue repair processes consist of a sequence of molecular and cellular events which occur after the onset of a tissue lesion in order to restore the damaged tissue. The exsudative, proliferative, and extracellular matrix remodeling phases are sequential events that occur through the integration of dynamic processes involving soluble mediators, blood cells, and parenchymal cells. Exsudative phenomena that take place after injury contribute to the development of tissue edema. The proliferative stage seeks to reduce the area of tissue injury by contracting myofibroblasts and fibroplasia. At this stage, angiogenesis and reepithelialization processes can still be observed. Endothelial cells are able to differentiate into mesenchymal components, and this difference appears to be finely orchestrated by a set of signaling proteins that have been studied in the literature. This pathway is known as Hedgehog. The purpose of this review is to describe the various cellular and molecular aspects involved in the skin healing process.

Graph 1

Sequential illustration of the stages involved in tissue repair

Figure 1

Accumulation of fibrin (asterisk) in the middle of the edema area in the extracellular matrix (Scanning Electron Microscopy – 4,500X)

Figure 2

Electromicrography of a leukocyte, with evident hydropic degeneration in the exsudative stage of the inflammatory process (Scanning Electron Microscopy – 7,000X)

Figure 3

Electromicrography that illustrates the pericyte (arrow) in close contact with the endothelial cell (asterisk), sharing the basal membrane of this cell, which makes up the blood vessel wall (Scanning Electron Microscopy – 7,000X)

Figure 4

Electromicrography presenting the part of the cytoplasm of a fibroblast that exhibits the hyperplasia of the endoplasmatic reticulum and mitochondria, illustrating an intense synthesis activity (Scanning Electron Microscopy – 12,000X).

Figure 5

Neoangiogenesis demonstrated by an immunomarker with an anti-alpha smooth muscle actin antibody in rat skin, three days after inducing the standard skin wound (Immunohistochemical - 100X).

Figure 6

Fibroplasia area demonstrating the absence of skin annexes in the extracellular matrix and complete reepithelialization of the epidermis (hematoxylineosin – 100X)

Figure 7

Electromicrography showing collagenous beams in different directions in the extracellular matrix, indicating the beginning of the process of fibroplasia, beginning on the seventh day after the onset of a skin wound, in an experimental model (Scanning Electron Microscopy – 12,000X)