Gene editing for Epidermolysis Bullosa
This project uses ‘molecular scissors’ to target and remove sections of the faulty gene for collagen VII which causes the skin fragility in Dystrophic Epidermolysis Bullosa (DEB). Using human skin samples taken from patients with either recessive (RDEB) or dominant (DDEB) forms of EB, this project will target and repair a range of different mutations (faults) within the collagen VII gene. Once corrected, the ability to make normal skin, as well as any side effects, will be assessed.
Conventional gene therapy approaches rely on gene addition of a corrected gene copy through viral vector transduction and such strategies are currently being applied to Recessive Dystrophic Epidermolysis Bullosa (RDEB) where there is defective collagen type VII protein. However, the use of constitutive exogenous promoters in viral vectors results in sustained gene expression that is not subject to the normal regulatory mechanisms of C7 expression. In addition, the integrating properties of vectors represent a risk for insertional mutagenic-derived events, considering possible pre-malignant states in certain cells in DEB. In addition, efficiency of gene transfer has been challenging given the large size of COL7A1 cDNA. Gene-editing tools, on the other hand, can be designed and engineered to target and repair a specific defined region of the DNA, thereby alleviating genomic toxicity and maintaining endogenous gene expression control.
Furthermore, conventional gene therapy through gene addition cannot treat the dominant form of Dystrophic EB (DDEB) where dominant negative mutations result in an abnormal gene product which adversely affects the normal product expression from the other allele. In such a scenario, gene editing with CRISPR/Cas9 has the potential to open new avenues for the treatment of DDEB. Therefore, this proposal aims to evaluate the feasibility of gene editing approaches using CRISPR/Cas9 system for both recessive and dominant forms of DEB.
Keratinocytes, fibroblasts and mesenchymal stem cells (MSCs), could be beneficial for cell therapy for DEB and patient-derived DEB induced pluripotent stem cells (iPSCs) may be useful in the future. We propose investigations into precision gene correction using CRISPR/Cas9 system, addressing critical aspects of nuclease and template delivery in these cell types, and modelling possible therapeutic strategies.
Naso, G et al. Cytosine Deaminase Base Editing to Restore COL7A1 in Dystrophic Epidermolysis Bullosa Human: Murine Skin Model. JID Innovations 3(3), 100191 (2023)