RDEB is one of the most severe rare genetic skin diseases of children and adults characterized by skin blistering resulting from lack of expression of type VII collagen. There is no treatment for this life-threatening disease. In March 2009, we obtained the orphan drug designation for the Medicinal product: “Skin equivalent graft genetically corrected with a COL7A1-encoding SIN retroviral vector”, which was developed during the THERAPEUSKIN project (FP6) to treat RDEB patients by ex vivo gene therapy. This approach uses autologous skin grafts made of primary keratinocytes and fibroblasts genetically corrected with a safe (SIN) retroviral vector expressing type VII collagen under the control of the EF1alpha promoter. We have demonstrated the feasibility of the approach in pre-clinical studies in mice and the absence of tumorigenicity. We now aim at preparing and undertaking a first clinical trial in 3 selected RDEB patients.This project will involve the transfer and the adaptation from the research laboratory to clinic, of the entire experimental procedure for genetic correction of RDEB skin equivalents suitable for transplantation in patients. This will include validation of the viral pilot batches and the GMP viral vector lot, the establishment of SOPs,the identification and selection of the best GMP culture system and the scale-up of the graft preparation. A clinical-grade cell bank of primary keratinocytes and fibroblasts will be established from 3 selected RDEB patients who are tolerant towards type VII collagen. Determination of transgene integrity, analysis of the proliferative capacities of transduced keratinocytes and the level of type VII collagen expression will be assessed. Safety assessment will include tumorigenicity assays, survey of grafted genetically corrected skin and integration site analysis. The regulatory and safety issues of these procedures related to the preparation ofclinical grade genetically modified cells suitable for human transplantation will be addressed. Authorization of the clinical trial by the AFSSAPS will allow the first patients to be treated and followed up. This “bench to bedside” project will serve as a proof of principle of safe gene therapy for RDEB. It has the potential to bring clinical improvement to these young patients and to represent a significant progress in the treatment of this devastating skin disease.