COL7A1 and recessive dystrophic epidermolysis bullosa: Although we isolated a small number of COL7A1 mRNA-expressing cells from PBMCs in healthy individuals, Tamai and colleagues reported that injured or necrotic epidermal cells in RDEB release high levels of high mobility group box-1 (HMGB-1), which recruits bone marrow-derived circulating mesenchymal cells to migrate and supply functional type VII collagen to regenerate the skin in RDEB [22].