Immune tolerance of allogeneic haematopoietic cell transplantation supports donor epidermal grafting of recessive dystrophic epidermolysis bullosa chronic wounds

Summary Background Chronic wounds, a common morbidity in recessive dystrophic epidermolysis bullosa (RDEB), lack definitive therapies. Objectives To assess allogeneic epidermal skin grafts in terms of wound healing and durability over time. Methods In a prospective, open‐label clinical trial for postallogeneic haematopoietic cell transplantation (post‐alloHCT) patients with RDEB, up to nine chronic wounds per patient were grafted over 1 year. Epidermal grafts measuring 5 cm2 were obtained from related alloHCT donors in the outpatient setting using the CELLUTOMETM Epidermal Harvesting System. Wounds were photographed and symptom inventories completed at baseline and 6, 12 and 52 weeks after grafting. The trial was registered at ClinicalTrials.gov (NCT02670837). Results Between August 2016 and January 2019, eight patients with RDEB received a total of 35 epidermal allografts at a median of 1157 days (range 548–2884) post‐alloHCT. The median (interquartile range) percentage reductions in wound surface area were 75% (52–94), 95% (72–100) and 100% (97–100) at 6, 12 and 52 weeks postgraft, respectively, each significantly reduced from baseline (P