Y chromosome and vimentin used to trace the fate of allogeneic keratinocytes delivered to the wound by the recombined human/pig skin

RHPS, composed of confluent allogeneic keratinocytes cultured on cell-free pig dermis, stimulates wound healing when applied with the keratinocyte lay er facing the wound. So far it has not been clarified whether the confluent keratinocytes implanted 'upside-down' can 'take' or only stimulate healing by producing growth factors. Confluent male keratinocytes were grafted ont o donor sites of three female patients. Biopsies were taken on days 4, 6 an d 9 after grafting. The fate of donor cells was followed in paraffin sectio ns by FISH for the Y chromosome and by persisting expression of vimentin ta ken as a marker of cultured keratinocytes. Histological evaluation was comp lemented by detection of keratin 10 and involucrin. All three donor sites h ealed within one week. On day 4 the early neoepidermis was multilayered but disordered after transplantation. A large proportion of cells were apparen tly of donor origin as indicated by the presence of Y chromosomes, irregula r morphology, expression of vimentin in the bottom and upper layers of the neoepidermis, and by irregular expression of involucrin and keratin 10 only in the central layer of the neoepidermis. From day 6 onwards, the new epid ermis acquired an ordered stratification. Involucrin and keratin 10 renewed normal distribution in suprabasal layers. Concomitantly, vimentin expressi on was decreasing. The Y chromosome was still found on day 6 but not on day 9. We concluded that confluent allogeneic keratinocytes temporarily 'take' to the wound and contribute to rapid wound closure, being replaced by the patient's epidermal cells after about one week.