GMEB-SASS: A Gene-Modified Skin Substitute for RDEB Treatment

Inclusion Criteria: * Age Learning phase: * Subjects 1 to 3: Eighteen (18) years old or older. * Subjects 4 to 6: Twelve (12) years old or older. * Subjects 7 to 9: Seven (7) years old or older. Other Inclusion Criteria: * Clinical diagnosis of recessive dystrophic epidermolysis bullosa (RDEB) with confirmed biallelic pathogenic variant in the COL7A1 gene. * Candidates - or their parents/caregivers if the candidates have limited comprehension, who are able to understand the study and to comply with the study procedures. * On the day of grafting, one or more blistered and/or erosive skin areas on the trunk and/or extremities large enough to graft at least three 25 to 50 cm2 GMEB-SASS grafts. * Ability to undergo anesthesia. Exclusion Criteria: * Medical instability limiting the ability to travel to the investigative center. * Any medical condition or illness that may impact study participation or compromise the safety of the participants, as per the investigator's judgment. * Evidence of systemic infection. * Current evidence or a history of non-metastatic or metastatic squamous cell carcinoma at the site to be grafted. * Any clinically significant abnormal laboratory values or abnormal findings identified during physical examination or through medical history that could compromise participant safety, as per the investigator's judgment. * History of or known allergy to bovine proteins. * Active drug or alcohol addiction. * Female candidate who are pregnant or breast-feeding. * Candidate who has received immunotherapy, including oral corticosteroids (Prednisolone \> 1 mg/kg), for more than one week, within 2 weeks prior to the study intervention (initial biopsy and GMEB-SASS grafting) (intranasal and topical preparations are permitted). * Candidate who has received chemotherapy within 60 days prior to the study intervention (initial biopsy and GMEB-SASS grafting). * Candidate who has received, in the last 6 months prior to the study intervention (initial biopsy and GMEB-SASS grafting), any gene therapy, chemical or biological product modifying collagen 7 expression.