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Notes: Summary In very extensive third-dregee burns, cutting the available healthy skin in the form of a mesh produces a much greater number of areas of epithelization. However, such grafts are exposed to lysis, infection and desiccation during the healing phase, and this conventional technique does not prevent infection and protein-loss on the wound surfaces. This led us to consider whether these disadvantages could be overcome by covering the area of the graft with a suitable material. On the basis of preliminary investigations we decided that, for mechanical, biological and immunological reasons, fetal calf skin constituted a suitable covering material. The trials were carried out on dwarf pigs. In each animal, three standardized wounds were made on the rear part of the body. These were then covered with autologous meshed grafts and then each of the three wounds was further covered with either fetal calf skin, collagen foil or a moist bandage. Under the cover of these xenografts, which were first treated with nucleic acids, distinctly better healing took place than with any other method. The application of this method in cases of extensive burns confirmed these experimental results. It could be demonstrated that complete epithelization is obtained very much more rapidly if the wound is covered with meshed autografts and protected with such a biological “dressing”, and also that the cosmetic results and functional restoration are superior to those obtained with conventional methods.

Notes: Summary Fetal calf skin from the first and second half of gestation was transplanted into grown male Sprague-Dawley rats. The transplant was fixed into the wound either by suturing or by a plastic adhesive. The fetal skin from the first half of gestation that was bonded completely to the wound margin showed a significant prolonged survival without immune suppression. Older or sutured fetal skin showed the usual acute rejection.

Notes: Summary In spite of acknowledged advantages for accomplishing early closure of large wounds using mesh grafts, the value of this method is limited by various disadvantages, such as continued loss of biological fluids, the lack of control of infection, and the eventual cosmetic disfigurement—which includes hypertrophic scarring. This paper discusses the use of sheets of foetal calf skin pretreated with nucleic acid to act as an immuno-suppressive agent. Studies have been carried out over the past 20 years by various workers on the use of foetal calf skin grafts as a dressing over healing areas. In humans it has been noted that there is a surprising lack of host reaction to these grafts. The process of epithelialisation has continued extremely satisfactorily underneath them, with a marked reduction in infection of burn wounds etc.—and in the ultimate degree of contraction of the resultant scars. The use of nucleic acids appears to increase the survival time of these protective xenografts from 21.5 days to 42.5 days (Fig. 1). Experimentally, three raw areas created on the backs of each of twelve Yorkshire pigs were covered first by mesh grafts (Fig. 2) and then by, (a) foetal calf skin pretreated with nucleic acids, (b) collagen, (c) moist saline dressings (Fig. 3). The mesh grafted defects covered with the foetal calf skin showed better healing and less contraction (Fig. 4). There was no destruction of the mesh graft and the level of the granulations was even and flat. This temporary covering remained firmly adherent until the entire area beneath was covered with epithelium, at an average time of 8 days. With the collagen sheets, the defects were epithelialised 1–2 days earlier, but contraction of the defect was appreciable. When wet dressings were used as covering material, partial loss of the mesh grafts was observed and a very pronounced wound contraction became obvious. Total epithelialisation took 10–12 days. In an attempt to evaluate clinically the use of foetal calf skin, pretreated as described, as a possible healing adjuvant on mesh grafts, we applied this material to eleven patients with large burn wounds or skin defects following avulsion injuries. The results confirmed the animal experiments. Infection was reduced and wound healing was accelerated. The technique and clinical progress in one patient with third degree burns is illustrated (Figs. 5–10). The combination of mesh grafts with these xenografts as a temporary coverage has proved to be remarkably useful in reducing and preventing infection and decreasing fluid loss. Healing is noticeably better beneath them, and its application stimulates markedly the growth of healthy, highly vascular granulation tissue, and thus encourages maximum take of the mesh grafts. It is apparent that the application of these xenografts serves not only as a stimulatory substance but also accelerates epithelialisation. Total epithelialisation of the interstices between the ribbons of the mesh graft was achieved between the 5th and 7th postoperative days in contrast to the usual time of between 9 and 12 days. The final appearance was improved cosmetically, and compared favourably to the use of sheet grafts. Scar formation and post-operative contraction were noticeably decreased.