By transfer of a curative transgene, we have achieved the full phenotypic reversion of primary keratinocytes of patients with a mild form of junctional epidermolysis bullosa (JEB) associated with genetic point mutations in the laminin beta3 gene. These findings confirm the feasibility of phenotypic reversion of adhesion-defective epithelial cells expressing a recombinant basement membrane protein, and pave the way to the gene therapy of genetic skin diseases.
Specifically, we have permanently transduced epidermal stem cells with replication-defective retroviral constructs carrying an exogenous cDNA. We have achieved a long-term expression of curative transgene in vivo following grafting onto athymic animals. We have demonstrated the stable gene correction in the epidermal stem cells isolated from JEB-patients and the possibility of cultivating large amount of genetically engineered epidermis in the GMP conditions. By long-term evaluation of cultured graphs, we have showed that the transplanted epithelia are indistinguishable from the normal epithelium.
This result comprises protocols and methods allowing correction of diseased skin keratinocytes by genetic manipulations. Methods for the reconstruction of skin and corneal epithelia have also been perfected.