Original Research The International Journal of Lower Extremity Wounds 9(3) 132–140 © The Author(s) 2010 Reprints and permission: http://www. sagepub.com/journalsPermissions.nav DOI: 10.1177/1534734610380024 http://ijlew.sagepub.com Viability and Efficacy of Coverage of Cryopreserved Human Skin Allografts in Mice Sonia Gaucher, MD 1,2 , Carole Nicco, PhD 3 , Mohamed Jarraya, MD, PhD 4 , and Frédéric Batteux, MD, PhD 1,3 Abstract Human skin allografts are considered one of the best temporary biological coverages for severe burn patients. Human skin allografts can be either viable or nonviable depending on their preservation modalities. However, there is a debate about the use of viable versus nonviable skin for severe burn patients because there is no established correlation between viability and efficacy of coverage. The authors tried to correlate the viability of cryopreserved human skin allografts as assessed by the MTT assay, with efficacy of coverage, intensity of rejection at day 8, and delay of wound healing in a xenograft model using human fresh skin (FS) and cryopreserved skin (CPS) on murine recipients (n = 49). Cryopreserved grafts were less rejectable than fresh grafts, with statistically significant different delays (P = .0008). Mice that had received grafts healed with delays; the delays, whether associated with fresh grafts or cryopreserved grafts, were not statistically significant. On day 8 after the graft, the overall damage score for the tissue’s histological architectural integrity was higher for FS. Furthermore, flow cytometry analysis showed a significant increase in the number of CD4 and CD8 T-cells (P = .001) in the spleens of FS-grafted mice. These results confirm that the use of viable CPS does not change the potential for healing. Keywords human skin allografts, burn, skin viability, allograft rejection The ultimate goal of all burn treatments is the early and complete closure of the burn wound. The best treatment of burn wounds is autografting. However, when autografts are not available because burn injuries are deep and extensive, skin substitutes have to be used. In this situation, human skin allografts (HSAs) are considered one of the best tem- porary biological coverages. 1-7 HSAs harvested from living or deceased donors are useful for different reasons: they limit water loss through evaporation and reduce pain through the mechanical effect on the wounds they cover, 8 reduce infection risk, 9 and boost tissue granulation, 10 thus, bring- ing together all the factors necessary for healing. 11 HSAs are temporary in nature, with the main drawbacks of their use being the risk of disease transmission. 12 In France, poor availability because of lack of donors and lack of harvesting is a limiting factor of the use of HSA. HSAs are inevitably rejected by the recipient. On non- immunocompromised healthy patients, HSAs are usually rejected within 8 to 10 days, 13(pp427-441) but on burn patients, this rejection is delayed as a consequence of the immunode- pression induced by extensive burns. 14 HSA rejection delay is not only linked to the recipient. It is also related to the method of skin preservation (ie, mode, type, and technique). The most useful procedures are cryopreservation, 15-17 stor- age at +4°C, 18-22 and glyceropreservation with high concentration of glycerol. 23,24 Therefore, it is possible, depending on the preservation process used, to divide the practice of HSA into 2 categories: viable and nonviable. 25 The HSAs stored at +4°C or that are cryopreserved are viable. In contrast, the glyceropreserved HSAs are not viable. Viable HSAs are revascularized after their grafting and then rejected between 2 and 4 weeks later. 26-28 It has been dem- onstrated that the nonviable glyceropreserved HSAs are not rejected as a result of the activation of Langerhans cells because this technique of preservation directly alters anti- gen presenting cells. 29,30 However, although the nonviable 1 Université Paris Descartes, Faculté de Médecine, Paris, France 2 Service des Brûlés, AP-HP Hôpital Cochin, Paris, France 3 Laboratoire d’Immunologie, IFR Alfred Jost, AP-HP Hôpital Cochin, Paris, France 4 Banque des Tissus Humains, AP-HP Hôpital Saint Louis, Paris, France Corresponding Author: Sonia Gaucher, Service des Brûlés, AP-HP Hôpital Cochin, Paris 75014, France Email: sonia.gaucher@cch.aphp.fr