Human keratinocyte stem cells survive for months in sodium chloride and can be successfully transplanted.

Human skin fragments can be preserved in anhydric sodium chloride at room temperature for periods of weeks or months and successfully transplanted, retaining normal morphological structure. Skin fragments of 10 x 10 x 6 mm were harvested during elective vascular and orthopedic surgery of lower limbs, dried of blood, and placed in anhydric sodium chloride powder in tightly sealed containers. Prior to transplantation to scid mice, the specimens were desalinated and rehydrated. Specimens preserved for 1-6 months and harvested 3-4 weeks after transplantation revealed intensive incorporation of bromdeoxyuridine (BdUR) into basal keratinocytes (stem cells). They expressed p63 and CD29 (stem cells and transient cells antigens), proliferating cell nuclear antigen (PCNA), and cytokeratin 16 specific for proliferating keratinocytes. We conclude that human epidermal stem cells can survive in a dehydrated state in sodium chloride for months and after transplantation give rise to keratinocyte progenies. Skin fibroblasts and some resident immune cells can also survive.

The effect of cyclosporine and tacrolimus on indigenous bacterial flora in human skin grafts.

Allogeneic skin transplants require intensive immunosuppressive therapy. Treatment protocols used for parenchymal organ grafts are not satisfactory to prevent skin graft rejection. Another factor responsible for the destruction of allogeneic skin transplants is bacterial inflammation. Temporary ischemia and the allogeneic reaction in transplanted skin cause increased permeability of the epidermis and the dermal capillaries, making skin grafts vulnerable to bacterial penetration. Moreover, immunosuppressive therapy compromises the host immune response. The present study assessed the effects of immunosuppression by cyclosporine (CsA) or tacrolimus (Tac) on the indigenous bacterial flora of transplanted human skin. We found that a 6-day course of treatment with CsA or Tac was followed by an increased prevalence of bacterial isolates, mostly evidenced by a change in the spectrum of graft bacterial flora from Staphylococcus aureus and coagulase-negative staphylococci toward more pathogenic strains such as Escherichia coli, Enterococcus faecium, micrococcus, and pseudomonas. The mouse skin adjacent to the graft remained sterile, precluding the possibility of graft contamination with mouse flora.

Differentiation of cellular reaction to alloantigens and bacterial infection in human skin graft--immunosuppressive drugs or antibiotics.

The human hand transplantations prompted revival of interest in evaluation of the rejection process of the grafted skin and its control with the antirejection drugs [1-3]. In case of first hand transplantation a combined immunosuppressive regimen was applied with currently available drugs resulting in acceptance of the entire composite graft. No major untoward systemic effects of antirejection therapy were observed. The most important clinical conclusion was that allogeneic skin can be accepted and function as in a normal extremity, although the attack of host cells on the graft can not be totally eliminated. Chronic perivascular and subepidermal infiltrates with recipient cells could be seen [4]. Another problem connected with skin transplantation is graft infection. Skin is inhabited by a specific spectrum of bacteria [5]. Allografted skin is more sensitive to bacterial penetration than normal skin due to local damage by the host-versus-graft cellular reaction and compromised immune reactivity to bacterial antigens by the immunosuppressive therapy. The histological pictures of rejecting skin represent a mixture of cellular reaction against the graft and penetrating microbes. Alloreaction requires modification of immunosuppressive regimen and infection is an indication for prolonged antibiotic therapy against skin bacterial flora. The question arises how to discriminate the alloreactive and bacterial changes in the skin graft. We studied the histological pictures of rejecting and infected human skin after transplantion to scid mice.