Ronald T. Plessinger

Storage media and temperature maintain normal anatomy of cadaveric human skin for transplantation to full-thickness skin wounds

Cadaveric human skin provides an optimal temporary cover after early excision of full-thickness burns; however, engraftment is reduced greatly by cryopreservation. Refrigerated skin is generally preferred because of its rapid revascularization, presumably caused by its greater viability. In this study, the effects of storage solutions, temperature, and the changing of the storage media on skin graft anatomy were evaluated as an indicator of graft viability. Split-thickness human skin grafts (0.012-0.015 mm) were retrieved from cadaveric donors and grafted to circumferential, full-thickness skin wounds on athymic mice. After clinical determination of engraftment 3 months after grafting, 6-mm punch biopsy samples of the human skin were harvested and separated into two groups. Biopsy samples were stored in either saline or Eagles minimal essential medium. Media were not changed or were changed every 3 days. All groups were stored at either 4 degrees C or room temperature (RT). After 5, 10, and 21 days of storage, biopsy samples were grafted onto athymic mice for 20 days. The biopsy grafts were then collected and prepared for histologic scoring on a scale of +4 (normal anatomy) to 0 (no epithelial cells). Significant differences in histologic scores were found by the nonparametric Kruskal-Wallis test followed by Wilcoxon pairwise comparison. Skin stored in media maintained better histologic anatomy than skin in saline, suggesting better maintenance of viability. There was also better preservation of anatomy after storage at RT for 21 days with media changes every 3 days when compared to unchanged media and all conditions at 4 degrees C. These results support the hypothesis that increased availability of nutrients and increased storage temperature maintain higher viability of cadaveric human skin for transplantation to full-thickness cutaneous wounds.

Can contamination of a patient's allograft be traced back to the allograft donor?

Cultures of allograft sites on burn patients occasionally show microbes that were not previously cultured from that patient. Our purpose was to determine 1) if microbes on allograft sites could have been transferred to the burn patient from the allograft donor and 2) if microbial transfer is different if the allograft was fresh or frozen. All allografts were cultured by the skin bank after recovery (pre-antimicrobial) and after the skin had been in an antimicrobial solution (post-antimicrobial). These culture results were compared with the results of cultures taken at the hospital from the allograft sites of burn patients. All allograft recipients at the burn hospital during 2005 were included in this Institutional Review Board approved study. Sixty-one donors provided 143 allografts for 38 patients. From the 61 donors, 114 precultures were taken; 19.5% were positive for at least one organism. Only 6.8% of 118 post-antimicrobial cultures were positive. Of the 143 allografts on burn patients, 111 were used fresh and 32 had been cryopreserved. During dressing changes, 124 cultures were taken from sites that received fresh allograft and 27 from sites that received frozen; 54.8% of cultures from fresh allograft sites and 41.5% from frozen sites (not significant, &khgr;2) were positive for microbes, which were mostly the patients own flora. None of the microbes isolated from the burn patient allograft sites matched organisms on the pre- or post-antimicrobial cultures from the donor allografts. Regardless of whether the allografts were fresh or frozen, no instances were identified in which donor microorganisms were transferred from a donor to a recipient.

Evaluation of the effect of topical steroids on human scar contracture using a nude mouse model.

Adult nude mice had 1.5 to 1.0 meshed split-thickness human skin applied to an excised area of their back. The animals were then randomized into two groups, one of which had a steroid cream applied to their graft on alternate days. The other group had no ointment applied and served as a control. The wounds were measured on a weekly basis and the rate of wound contracture was found to be identical. Topical steroids would thus appear to offer no benefit in the prevention of scar contracture.