Skin Grafts

Sometimes, the germinal portion of epidermis is destroyed, and new skin cannot regenerate. Such wounds require skin grafts.

The most successful type of skin graft involves the transplantation of a segment of skin from a donor site to a recipient site of the same individual (autograft) or an identical twin (isograft).

If skin loss is so extensive that conventional grafting is impossible, a self-donation procedure called autologous skin transplantation may be employed. In this procedure, used most often on severely burned patients, small amounts of an individual's epidermis are removed and grown in the laboratory to produce thin sheets of skin. 

Then, they are transplanted back to the patient where they adhere to burn wounds are generate a permanent skin to cover burned areas. 

The process normally takes three to four weeks. Since hair, sweat glands, and oil glands develop from the epidermis, they can assist in replacing the epidermis removed for an autologous skin transplant. The obvious advantage to this procedure is that a lot of new epithelium can be grown from a very small skin sample. 

During the waiting period, wound dressing or skin from another person (homograft), such as a cadaver, or animal (heterograft) may be used to help protect the patient from potentially fatal fluid loss and infection. 

Although homografts and heterografts are temporary because they are ultimately rejected by the immune system, they prevent loss of fluid, electrolytes and protein from burn site while also decreasing pain and increasing the patient's mobility.

One type of synthetic skin that is used as part of autologous skin transplantation consist of a protective plastic layer that serves as the temporary epidermis and an underlying layer composed of collagen fibers and cartilage derived from animals that serves as the temporary dermis. 

After the synthetic skin is applied to the burned area, fibroblasts produce collagen fibers to replace those in the synthetic skin, which decompose. After a few months, when the reconstruction of the dermis is complete, sheets of the patient's newly grown epidermis are transplanted over the wound area.