High-dose CD150⁺CD48⁻ BM from Col7a1 wild-type congenic donors corrects basement membrane zone defect. (A) Anchoring fibrils are fan-shaped structures in the skin that are composed of col7 protein. Transmission electron microscopy demonstrates that anchoring fibrils emanate from the papillary dermis into the lamina densa (top panel, arrows) in the wild-type skin (as expected), and in the skin of treated RDEB animals (bottom panel, arrowheads). No anchoring fibrils are deposited at the skin basement membrane zone in the RDEB skin (middle panel). D indicates dermis; E, epidermis; LL, lamina lucida; LD, lamina densa; and HD, hemidesmosome. (B) Skin blisters characteristic of RDEB healed in all 3 long-term surviving Col7a1^−/− recipients of CD150⁺CD48⁻ BM (top panel, arrow points to a skin blister at 3 days of age; bottom panel, 10 weeks of age). Representative examples are shown. Camera: Coolpix 4300 (Nikon, Tokyo, Japan).