Prior to skin transplantation, human fibroblasts were apparent in the scleroderma donor skin, whereas 4 wk posttransplantation, scleroderma skin grafts were largely devoid of human fibroblasts with only rare human PDGFRA positive cells (arrowheads) and were replaced by mouse fibroblasts. This evidence concerns the gene PDGFRA and scleroderma.