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Skin Banking

Skin Banking is a process in which skin is removed from a donor body, tested for suitability as a graft material, packaged, stored, and finally reused as a graft. The process is similar to that for blood banking. Skin grafts can be autografts or allografts.

An autograft is tissue which is removed from and then used on the same individual. Auto-skin grafts can be used as a treatment for 2nd and 3rd degree burns and for reconstructive surgery. Skin autografts are permanent replacement grafts and will heal full thickness burn wounds. Autografting requires that skin be removed from a "donor site". Autografts involve the removal the epidermis and some of the dermis but are not deep enough to remove the hair follicles and glands. Therefore, the epidermal cells within the hair follicles and glands can regenerate (grow) a new epidermis over the donor site while the skin graft provides a new epidermis and some dermis to the wound it covers. Because autografts are thin and usually don't contain hair follicles or glands, the grafted areas will be devoid of hair and unable to sweat.

Allografts are tissue that is removed from one individual and used on a different individual. Allograft skin is used as a temporary burn wound graft and will be rejected by the recipient, usually within 7-21 days. Until rejection, however, allograft skin will provide many of the functions of healthy skin. Skin allografts will close a wound providing a barrier against infection and fluid loss, decrease pain, and promote healing of underlying tissues. Skin allografts are use as a transitional treatment until autografting can permanently close the burn wound. Allograft skin is obtained from cadaveric (deceased) donors after consent is obtained from the next-of-kin. Tissue donors are carefully screened by reviewing past and present medical records, interviewing medical staff, interviewing the next-of-kin for past medical history and high risk lifestyles. Samples of the donor's blood are also tested for many transmissible diseases including hepatitis and AIDS.

Allograft skin may be used fresh or frozen. Fresh skin allografts are considered by some to be more desirable because they are more viable (alive) than frozen grafts. Others feel that viability is unimportant because the grafts are only temporary. Fresh skin grafts are maintained in a fluid medium intended to keep the cells alive and nourished. Fresh storage will only maintain skin grafts for approximately 14 days. It may take upwards of 10 days to release tissue from quarantine due to bacterial and serologic testing therefore, most skin banks freeze their tissue grafts. Freezing skin grafts involves soaking the tissue in special medium (cryoprotectants) and then freezing the tissue grafts in a controlled environment. Cryoprotectants are intended to minimize the freezing injury to cells. Most tissues are control-rate frozen at 1-5 degrees Centigrade per minute and then stored at ultra-low temperatures (below -60 C). Frozen grafts can have a shelf life of up to five years.