AN ANIMAL-MODEL TO STUDY THE SIGNIFICANCE OF DERMIS FOR GRAFTING CULTURED KERATINOCYTES ON FULL-THICKNESS WOUNDS

Autologous cultured keratinocytes grafted onto full thickness wounds t ake poorly, and any epidermal cover that is produced is unstable. Howe ver, a more stable epidermis has been reported when keratinocytes are grafted onto a dermal surface. We have developed a skin grafting model using a polytetrafluoroethylene (PTTE) skin graft chamber in the dome stic pig. The chambers isolate individual wounds and prevent epithelia l migration from the wound edge. Dermal grafts were prepared by enzyma tic separation of the epidermis from split skin to leave a de-epiderma lized dermis (DED). Full thickness wounds were initially grafted with autologous DED and, subsequently, 7 days later with cultured autologou s keratinocytes. The wounds were biopsied serially over 6 weeks, and p rocessed for histology, immunocytochemistry and electron microscopy. C linically, the grafts were seen to mature over the 6-week period. In 1 4/20 wounds, 40-72 per cent of the wound areas (as assessed by image a nalysis) had acquired epidermal cover at day 14. In 6/20 wounds, the e pidermal cover was 0-27 per cent. The skin surface was stable at day 2 1. At this time electron microscopy and immunohistochemistry demonstra ted a continuous, well formed basement membrane. The epidermis was ini tially acanthotic, but was histologically mature by day 14. Surprising ly, the dermal grafts were broken down by day 14. However, a neodermis formed beneath all areas with epithelial cover 21 days after grafting the keratinocytes. In this model, we have demonstrated the advantage of providing a dermal bed for cultured keratinocytes.