Gene therapy: pursuing restoration of dermal adhesion in recessive dystrophic epidermolysis bullosa

The replacement of a defective gene with a fully functional copy is the goal of the most basic gene therapy. Recessive dystrophic epidermolysis bullosa (RDEB) is characterised by a lack of adhesion of the epidermis to the dermis. It is an ideal target for gene therapy as all variants of hereditary RDEB are caused by mutations in a single gene, COL7A1, coding for type VII collagen, a key component of anchoring fibrils that secure attachment of the epidermis to the dermis. RDEB is one of the most severe variants in the epidermolysis bullosa (EB) group of heritable skin diseases. Epidermolysis bullosa is defined by chronic fragility and blistering of the skin and mucous membranes due to mutations in the genes responsible for production of the basement membrane proteins. This condition has a high personal, medical and socio-economic impact. People with RDEB require a broad spectrum of medications and specialised care. Due to this being a systemic condition, most research focus is in the area of gene therapy. Recently, preclinical works have begun to show promise. They focus on the virally mediated ex vivo correction of autologous epithelium. These corrected cells are then to be expanded and grafted onto the patient following the lead of the first successful gene therapy in dermatology being a grafting of corrected tissue for junctional EB treatment. Current progress, outstanding challenges and future directions in translating these approaches in clinics are reviewed in this article.