Antibiotic susceptibility and resistance of Staphylococcus aureus isolated from fresh porcine skin xenografts: risk to recipients with thermal injury

Skin xenotransplantation: Historical review and clinical potential

Half a million patients in the USA alone require treatment for burns annually. Following an extensive burn, it may not be possible to provide sufficient autografts in a single setting. Pig skin xenografts may provide temporary coverage. However, preformed xenoreactive antibodies in the human recipient activate complement, and thus result in rapid rejection of the graft. Because burn patients usually have some degree of immune dysfunction and are therefore at increased risk of infection, immunosuppressive therapy is undesirable. Genetic engineering of the pig has increased the survival of pig heart, kidney, islet, and corneal grafts in immunosuppressed non-human primates from minutes to months or occasionally years. We summarize the current status of research into skin xenotransplantation for burns, with special emphasis on developments in genetic engineering of pigs to protect the graft from immunological injury. A genetically-engineered pig skin graft now survives as long as an allograft and, importantly, rejection of a skin xenograft is not detrimental to a subsequent allograft. Nevertheless, currently, systemic immunosuppressive therapy would still be required to inhibit a cellular response, and so we discuss what further genetic manipulations could be carried out to inhibit the cellular response.

Observation of viable alloskin vs xenoskin grafted onto subcutaneous tissue wounds after tangential excision in massive burns

Background

Staged excision and grafting with viable cryopreserved alloskin or fresh pigskin at an early stage is a main strategy for wound management in massive burns. Alloskin is the gold standard of a biological temporary skin substitute, and the main drawback to its wider use is the limited number of donors. In this paper, we compare the use of fresh pigskins to cryopreserved alloskins as temporary skin substitutes on subcutaneous tissue wounds after tangential excision by observing the clinical performances of these grafts in cases of a massive burn.

Methods

We selected six adult massive burn patients undergoing tangential excision and skin grafting on subcutaneous tissue wounds (TESGSTW) at our burn center from January 1, 2003 to December 31, 2013. The general clinical data and survival percentage of skins at postoperative weeks (POWs) 1, 2, and 3 were analyzed. In our clinical practice, we also observed the phenomenon that several viable cryopreserved alloskin or fresh pigskin grafts used as temporary coverage on subcutaneous tissue wounds had long-term survival after repeated desquamation. The macroscopic and histological results of one typical case were also analyzed.

Results

In this study, the first three TESGSTW operations were performed at 2–3, 5–8, and 11–16 days post-injury. The operation areas were 30.3 ± 7.9 % total body surface area (TBSA), 19.0 ± 6.0 % TBSA, and 12.0 ± 1.7 % TBSA, respectively. The survival percentage of the cryopreserved alloskins or fresh pigskins at POWs 1, 2, and 3 were 80.0 ± 10.0 % vs 75.7 ± 5.3 % (t = 1.01, P = 0.16), 71.2 ± 10.6 % vs 66.4 ± 6.2 % (t = 1.09, P = 0.30), and 48.7 ± 2.5 % vs 35.0 ± 7.0 % (t = 3.83, P = 0.03), respectively. The microscopic observation of the survival of alloskins or pigskins in one typical case showed rete ridges and a basilar membrane at the joint of the epidermis and dermis at an early stage; these structures disappeared with extended time post-operation.

Conclusions

From the clinical observations, fresh pigskin and cryopreserved alloskins could be used with equal effectiveness at an early stage (within 2 weeks post-operation) as temporary coverage on massive burns after TESGSTW. After engraftment, several cryopreserved alloskins or fresh pigskins could co-survive in a massive burn patient for an extended amount of time. The co-survival of alloskin and pigskin will provide clues for further research into skin transplantation.

Electronic supplementary material

The online version of this article (doi:10.1186/s41038-016-0045-9) contains supplementary material, which is available to authorized users.