Skin banks play a critical role in the management of complex wounds, particularly in the treatment of severe burns. These specialized facilities are responsible for the procurement, processing, preservation, and distribution of human skin tissue primarily used as temporary biological coverage. In this chapter, we will focus specifically on the types of skin substitutes and biologic materials processed and dispensed by hospital-based skin banks, which traditionally serve the needs of regional burn centers and surgical units. These include cadaveric skin allografts, human amniotic membrane (HAM), and in selected European centers, human acellular dermal matrices (HADM) or de-epidermized dermis (DED) prepared within the skin bank itself. It is important to distinguish hospital skin banks from a broader category of tissue banks, many of which are managed by private or commercial entities. These organizations may offer a wide and evolving range of biologic and synthetic graft materials—such as decellularized dermis, bone allograft, bone matrix, cartilage allograft, tendon allograft, fascia allograft, xenograft, and various advanced wound matrices—that are not within the direct purview of traditional skin banks. The discussion of such commercially produced and rapidly changing products is beyond the scope of this chapter. A complete list of establishments accredited by the AATB (American Association of Tissue Banks) can be found online.

Our aim is to provide a clear and practical overview of the standard products routinely processed and provided by hospital skin banks, their indications, limitations, and clinical applications, particularly in the context of burn surgery and reconstructive care.

The most used hospital skin bank product is skin allograft. After excision and debridement of deep partial-thickness or full-thickness burns, allograft skin is frequently used as a temporary biologic dressing. Allografts are harvested from cadaveric human donors and typically consist of split-thickness skin including both epidermis and part of the dermis. Their primary role is to provide immediate physiologic wound coverage—protecting the underlying tissue from infection, minimizing evaporative fluid and heat loss, reducing pain, and preparing the wound bed for eventual definitive closure. Allografting serves not only as protection but also as a biologic “test dressing” that allows for assessment of the wound bed’s viability; successful adherence and graft take indicate a vascularized surface suitable for final grafting. This approach is particularly valuable in patients with extensive burns who may not have sufficient donor sites available or are not yet physiologically stable for definitive skin grafting. By temporarily covering the wound, the allograft allows the wound to stabilize, promotes granulation, reduces the risk of contamination, and provides time for donor site recovery. Although initially viable, allografts are immunologically foreign tissue and are therefore not permanently accepted by the host. Within 7 to 14 days, they are progressively rejected by the recipient’s immune system, undergo necrosis, and are subsequently sloughed off. This predictable rejection is not considered a treatment failure but rather an expected and essential phase in the staged management of complex burn wounds. Allografts thus play a critical role in bridging the gap between excision and definitive coverage with an autologous split-thickness skin graft (STSG). In many cases, the autologous STSG is typically performed on day 7–10 after the application of allograft, but this can be earlier or later depending on individual patient needs. Before applying the autologous STSG, the residual allograft that eventually took and got incorporated is excised, so that the wound bed is prepared to host the final autologous STSG.

A skin bank is a facility that stores and distributes donated epidermal and dermal tissue and amnion for use in medical procedures such as grafting. The stored skin is called allograft or homograft, and it is harvested from human cadavers. Donated skin from cadavers is carefully screened, processed, and stored to ensure its quality and safety.

By providing a source of donated skin tissue, the skin bank can help to ensure that patients receive the care they need in a timely manner, which can be critical for their recovery.

In addition to providing a source of skin tissue for grafts, the skin bank can also help to reduce the risk of complications associated with skin grafts. Donated skin tissue is carefully screened and processed to ensure that it is disease-free and noncontaminated, which is particularly important in burn patients, who have profoundly decreased immune function and are therefore susceptible to a multitude of opportunistic and nosocomial infections. This can help to reduce the overall risk of infection and other complications that can arise from skin grafts and can improve the overall success rate of the procedure. Another benefit of the skin banks is that they can help to reduce the demand for live skin donors. In the past, skin grafts were often performed using skin taken from other parts of the patient’s body (autograft). However, this can be a painful and invasive procedure, and it may not be feasible in cases where the patient has suffered extensive burns or injuries. The application of allograft is only a temporary solution because the patient will eventually need autograft when their condition improves, but the utility in providing temporary coverage lies in the ability to improve wound healing, reduce fluid loss and electrolyte imbalances, and ultimately reduce mortality. ^,

Furthermore, biologically active cryopreserved human skin allografts (homograft) have been found to be safe and effective in treating wounds with exposed bone and/or tendon, which are notoriously difficult to successfully provide coverage for.

Products processed, stored, and distributed by the skin bank include:

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  Skin from cadavers (called allograft or homograft). This is typically a Split-Thickness Skin Allograft that includes epidermis and part of dermis but can also be a be a Full-Thickness Skin Allograft which includes the entire epidermis and the full dermis. Fresh or Fresh-Frozen Human Skin is available in some academic hospital tissue banks; it has a very short shelf life (5–10 days) and its use is rare; it is used when living cells are preferred.

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  Dermis (de-epidermized dermis [DED] ^, and human acellular dermal matrix [HADM]) only available in European skin banks, due to specific regulations .

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  Human amniotic membrane (HAM or human amnion)

Allograft skin is widely used for wound management in burn centers and it functions as biological dressing for the burn wound.

The production of DED by the skin bank of Siena, Italy, and its properties have been described by Fimiani et al. and by Tognetti et al. To prepare the DED, the skin is de-epidermized manually. DED can be cryopreserved or glycerol-preserved and has several indications including full-thickness burns. The skin can also be de-epidermized using the sodium chloride solution method.

The DED can then undergo a decellularization process to produce HADM. HADM has been used since 1995 for burn-wound treatment. Moreover, split-thickness skin grafting on HADM scaffold for the treatment of deep burn wounds has been described by several authors. HADM acts as a dermal scaffold for neodermis and neoepidermis formation in deep-dermal burn wounds. Extracellular matrix (ECM) is the largest element of the dermal layer, and its components include proteoglycans, hyaluronic acid, collagen, and elastin. Human acellular dermal matrices provide an ECM scaffold used to treat deep burn wounds.

The HAM is a waste product in cesarean section procedures and normal labor, therefore it has no ethical objections. ^, Amnion has been shown to alleviate pain, prevent infection, reduce pruritus, and accelerate wound healing. ^{, ,} Our institution has used amniotic membrane for temporary total ocular surface coverage in the treatment of toxic epidermal necrolysis, which has shown improvements in corneal clarity, conjunctival scaring, and dry eye symptoms at 3-month follow-up as compared with a historical group that received maximal medical treatment available. Furthermore, dehydrated HAM wound dressing is a safe alternative to cadaveric allografts in treating pediatric partial-thickness facial burns.

The preparation and storage of amnion has been a role for many skin banks around the world. Although using human amnion as a temporary biological wound dressing is inferior to allogenic skin, it is an excellent, cost-effective means of burn treatment in developing countries that experience a high incidence of burn injuries complicated by financial constraints. ^, Although these countries may not be able to finance costly skin banks, the procurement and storage of amniotic membrane is affordable comparatively, relatively easy to execute, and provides a reliable and long-lasting resource for burn wound coverage.

In a recent meta-analysis, Yang et al. found out that HAM treatment was more effective than conventional methods, silver sulfadiazine, and polyurethane membrane in treating burn wounds, but HAM appeared to be less effective than honey. Other products are not typically dispensed by hospital skin banks, but are produced, stored and dispensed by private biotech/wound care companies (for example Acellular Dermal Matrices like AlloDerm, FlexHD, Bioengineered skin like Apligraf or Dermagraft, and injectables like micronized dermis; these are not hospital skin bank products).

The idea of storing human skin stemmed from Wentscher in 1903 when he reported cellular viability of human skin after it was refrigerated for 3 to 14 days. However, it was not until the 1930s that blood and tissue banking took their place in the clinical practice of medicine. The clinical utility of allograft skin in burn-wound coverage was first described by Bettman in 1938. He reported his success in the treatment of children with extensive full-thickness burn injuries and pleaded for the use of homogenous Thiersch grafts as lifesaving measures against otherwise fatal sepsis. Webster and Matthews later described the successful healing of skin autografts stored for 3 weeks at 4°C to 7°C; however it was not until 1949, after the establishment of the US Navy tissue bank, that modern-day skin banking began. In 1960, the first tissue bank in Europe was founded in England, the Yorkshire Regional Tissue Bank, and the Netherlands followed suit in 1976 with establishment of the Dutch National Skin Bank, now known as the Euro Skin Bank.

The establishment of skin banking signaled the beginning of significant research related to the processing, preservation, and storage of human tissues. Baxter explored the histologic effects of freezing on human skin and discovered that the formation of ice crystals caused the destruction of skin architecture. This was followed in 1952 by the pioneering research of Billingham and Medawar, who demonstrated that skin could be effectively cryopreserved using glycerol. Soon afterward, Taylor was able to demonstrate that the addition of glycerol to storage solutions decreased ice crystal formation in frozen tissues. These advancements permitted Brown and Jackson to popularize the use of allogeneic human skin grafts as biologic dressings for extensive burns and denuded tissue. By 1966, Zaroff had reported the 10-year experience using allograft skin in the treatment of thermally injured patients at the Brooke Army Medical Center. In this report, he described the mechanical and physiologic advantages of allograft skin as a biologic dressing. In 1966, Cochrane reported the first successful use of frozen autologous skin grafts after controlled-rate freezing in 15% glycerol and rapid rewarming before implantation. This was followed by Morris’s report demonstrating the beneficial effects of using allogeneic skin in the treatment of infected ulcers and other contaminated wounds and by Shuck’s report suggesting the potential use of allogeneic skin in the treatment of traumatic wounds based on their Vietnam War experience. These increased uses of allograft skin led to further research into the beneficial effects of allograft skin on wound healing, including its association with a reduced incidence of bacterial infections ^, and the stimulation of wound bed neovascularization. ^,

Bondoc and Burke are credited with the establishment of the first functional skin bank in 1971. Their experience with allograft skin led to a report of successful burn-wound excision and allografting with temporary immunosuppression in children with extensive injuries. Today, allograft skin remains an ideal temporary cover for extensive or excised cutaneous or soft-tissue wounds, particularly when sufficient autograft skin is not available or when temporary wound coverage is desired. Currently, many synthetic skin substitute dressings are available in the market.

One biologic dressing with a long history in the treatment of burned patients is amniotic membrane. It was initially introduced for skin transplantation by Davis in 1910 and was subsequently described for use on burned and ulcerated skin by Sabella in 1912. ^, During the immediate period after these reports, the use of amniotic membranes was attempted as permanent skin replacements, although the grafts were rejected. In 1952, Douglas was the first to report the use of amniotic membrane as a temporary burn wound covering. Since that time, amnion has been one of the tools available in the treatment of partial-thickness burns. ^{, , ,}

The widespread use of allograft skin in the management of patients with extensive burn, traumatic, and soft-tissue injuries has had a major impact on the number of skin banking facilities over the past two decades. Consequently, the majority of skin banks have been founded close to regional burn centers or within burn center hospitals themselves. Skin banks must therefore maintain a close working relationship with regional burn centers, not only to meet the specific needs of the burn surgeon, but also to help generate community support for skin donation through combined educational outreach programs.

From 1969 to 1988, there was a steady growth in the number of skin banks. This number of banks eventually began to decline and reached its nadir in 2002. Since that time, however, there has been a steady increase in the number of skin banking facilities to its current total of 74 American Association of Tissue banks (AATB)- Accredited Establishments that recover, process, store, and/or distribute skin for transplantation worldwide. Fig. 13.1 shows the total number of skin donors and the total square feet of skin distributed by skin banks throughout the United States and Canada from 1995 through 2015.

Skin donation and distribution in the United States and Canada, 1995–2015.

As skin banking facilities grew in number, it became apparent that policies and procedures required standardization. This was quite difficult initially because there were insufficient data to develop a consensus regarding standards of practice. As early as 1976, the AATB had begun to address this issue by the formation of a Skin Council. This provided a forum for the discussion of skin banking practices and was complemented by the activities of the American Burn Association’s (ABA) Skin Banking Special Interest Group. The Standards and Procedures Committees were created in 1977 and produced the first guidelines for tissue banking in 1979. The first Standards for Tissue Banking were published in 1984, and tissue-specific technical manuals (including skin) were developed in 1987. ^, Since that time, the Standards have been modified and refined based on consensus and, where available, supportive scientific research, with the latest (14th) edition released in 2016. In addition, shortly after the development and promulgation of its Standards for Tissue Banking, the AATB created an inspection and accreditation committee in 1982 and began conducting voluntary inspections in 1986. This program continues today and is important in ensuring that tissue banks adhere not only to AATB Standards but also the US Food and Drug Administration (FDA) regulations governing all aspects of human tissue banking. In 1992, the AATB presented its Year 2000 Plan, outlining the institution’s goals of supporting tissue and cell banks and ensuring the safety and quality of tissues, as well as advancing and strengthening the AATB. The AATB has worked with many organizations, such as the FDA, the Centers for Disease Control and Prevention, and the ABA, to update standards and quickly respond when necessary, such as through the timely creation of instructions and methods to screen potential donors for emerging infectious diseases, including the COVID-19/SARS-CoV-2, monkeypox, West Nile, Ebola, and Zika viruses to reduce risk of infection. Currently, 128 worldwide AATB-accredited tissue banks are listed on the AATB website. Only 74 of them have skin products available in some form, and fewer (estimated around 50) are hospital skin banks. The FDA’s search of registered tissue banks is available online.

Another use of allograft skin has been to apply it as an overlay on top of widely expanded, meshed autologous skin graft ( Fig. 13.3 ). This technique was originally described using meshed allograft and provides immediate closure that can be both temporary and permanent. Our institution uses 2:1 meshed cadaver skin for the coverage of widely expanded autografts (with a ratio greater than 2:1). Because it is usually less viable than fresh skin, it functions more as a biologic dressing than as a temporary skin replacement. Its adherence to the underlying wound bed results in pain relief, limitation of exudative and water loss, and reduces the need for frequent dressing changes. As the underlying wound bed reepithelializes, the allograft slowly separates without disturbing the delicate underlying epithelium. These properties of frozen allograft are also used in the coverage of partial-thickness wounds. Studies by Rose and Naoum demonstrated more rapid healing times and shorter hospital stays for children with extensive partial-thickness burns when treated with early wound debridement and allografting compared with conventional topical antimicrobial therapy.

Diagrammatic illustration of meshed allograft overlay technique (as described by Alexander et al.). The allograft is generally meshed 1.5:1 or 2:1, whereas the underlying autograft may be meshed 3:1 or greater.

(From Alexander JW, MacMillan BG, Law E, et al. Treatment of severe burns with widely meshed skin autograft and widely meshed skin allograft overlay. J Trauma. 1981;21:433-438.)

There has also been some concern that allografts may induce an inflammatory rejection response resulting in delayed reepithelialization of underlying autografts. Therefore the use of lyophilized tissue has been suggested because the lyophilization process destroys cellular components and results in a diminished immunologic response from the graft recipient. ^, A 2013 study of 11 patients treated with lyophilized allograft showed no evidence of immunologic reactions due to the administration of allograft.