Evaluation of Graftskin composite grafts on full-thickness wounds on athymic mice

We used a living bilayered cultured skin replacement to close full-thickness wound defects on the dorsum of athymic mice. The skin replacement is composed of human fibroblasts that condense a bovine collagen lattice; the lattice is then seeded with cultured human keratinocytes. The collagen lattice with fibroblasts serves as a dermal template, and the overlying human keratinocytes form the epidermal component of this composite skin replacement. Twenty-four animals were grafted, and groups of six were killed and biopsied at 6, 15, 30, and 60 days after graft replacement. Twenty-four mice in the control group receiving grafts of fresh, split-thickness, human cadaver skin were biopsied at the same time points. "Take" of all grafts was excellent, with only one graft loss in the 48 mice (one Graftskin graft, at 15 days). Light microscopy revealed that vascular ingrowth into Graftskin occurred rapidly, and discrete dermal and epidermal layers were seen at all time points. Evidence of basement membrane formation was seen at 6 days after grafting by immunohistochemical staining for laminin and by electron microscopic visualization of lamina lucida and lamina densa zones at the dermal-epidermal junction. The results demonstrated that Graftskin formed a structurally complete skin replacement within 1 week of placement on full-thickness wounds on athymic mice, and effective skin coverage was provided for the 60-day observation period after grafting.