Impaired wound healing

Wound healing is the process of repair that follows injury or infection or due external parasite to the skin and other soft tissues. The capacity of a wound to heal depends in part on its depth, as well as on the overall health and nutritional status of the individual. Wounds that exhibit impaired healing, including delayed acute wounds and chronic wounds, generally have failed to progress through the normal stages of healing. Such wounds frequently enter a state of pathologic inflammation due to a postponed, incomplete or uncoordinated healing process.

Multiple factors can lead to impaired wound healing. In general terms, the factors that influence repair can be categorized into local and systemic. Local factors are those that directly influence the characteristics of the wound itself, while systemic factors are the overall health or disease state of the fish that affects its ability to heal.

Nutrition has been recognized as a very important factor that affects wound healing. Protein is one of the most important nutrient factors affecting wound healing. A deficiency of protein can impair capillary formation, fibroblast proliferation, proteoglycan synthesis, collagen synthesis and wound remodeling. A deficiency of protein also affects the immune system, with resultant decreased leukocyte phagocytosis and increased susceptibility to infection. Collagen is the major protein component of connective tissue and is composed primarily of glycine, proline, and hydroxyproline. Collagen synthesis requires hydroxylation of lysine and proline and co-factors such as ferrous iron and vitamin C. Impaired wound healing results from deficiencies in any of these co-factors.

Vitamins C (L-ascorbic acid), A (retinol), and E (tocopherol) show potent anti-oxidant and anti-inflammatory effects. Vitamin C has many roles in wound healing and a deficiency in this vitamin has multiple effects on tissue repair. Vitamin C deficiencies result in impaired healing and have been linked to decreased collagen synthesis and fibroblast proliferation, decreased angiogenesis, and increased capillary fragility. Also, vitamin C deficiency leads to an impaired immune response and increased susceptibility to wound infection. Similarly, vitamin A deficiency leads to impaired wound healing. The biological properties of vitamin A include anti-oxidant activity, increased fibroblast proliferation, modulation of cellular differentiation and proliferation, increased collagen and hyaluronate synthesis and decreased MMP-mediated extracellular matrix degradation.

Oxygen is also important for cell metabolism, especially energy production by means of ATP and is critical for nearly all wound-healing processes.