Base and prime editors are novel CRISPR variants that reduce the risk of off-target effects by avoiding double-stranded DNA cleavage, bypassing the need for homology-directed repair. As such, these tools offer great therapeutic potential for inherited skin diseases such as recessive dystrophic epidermolysis bullosa (RDEB), a severe blistering skin disorder caused by bi-allelic loss-of-function mutations in COL7A1, which encodes type VII collagen (C7) the major component of anchoring fibrils in skin basement membrane. Current therapies for RDEB are limited, but ex vivo and in vivo COL7A1 base or prime editing therapies offer the potential of a single intervention treatment to restore normal protein production. This study compared DNA editing specificity, safety, and efficiency on RDEB fibroblasts harbouring a homozygous c.4448 G>A (p.Gly1483Asp) mutation in COL7A1. First, we corrected the pathogenic mutation on both alleles in primary patient fibroblasts, using adenine base editor (ABE8e) mRNA together with single guide RNA (sgRNA). Lipofectamine MessengerMax was used to deliver the ABE and sgRNA systems into the cells. Different concentrations of sgRNA to ABE demonstrated 100% bi-allelic correction using a 1:2 ratio of sgRNA to ABE8e; this correction was achieved without introducing any bystander mutations. The functionality of this correction is being evaluated with western blot and in 3D skin models. Our pre-clinical translational research findings underscore the potential of base editing as an efficient and safe gene therapy strategy for RDEB.

ESDR283 - Optimising specificity and applicability of base editing for COL7A1 mutations in recessive dystrophic epidermolysis bullosa

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.