Kurzfassung

Gene therapies offer new possibilities for the precise correction of monogenic disorders. Here, we present the first prime editing (PE)-based gene repair strategy for pathogenic COL17A1 variants that cause junctional epidermolysis bullosa (JEB). Type XVII collagen (C17), encoded by COL17A1, plays a critical role in skin aging, regeneration, and the maintenance of epidermal stem cell integrity. Treatment of primary human JEB keratinocytes with PE mRNAs resulted in COL17A1 editing efficiencies of up to 60% in bulk-treated cells, leading to the restoration of full-length, accurately shed C17. Chromosomal aberrations analysis by single targeted linker-mediated PCR sequencing analysis of gene-edited JEB keratinocytes confirmed the absence of unintended chromosomal rearrangements at potential off-target sites and only minimal on-target aberrations. Remarkably, in a xenograft model, in which C17 + cells represented only 55.9% of the input population, COL17A1-corrected cells populated 92.2% of the basal keratinocyte layer in the resulting skin grafts after 6 weeks. These observations highlight a potential selective advantage imparted by C17 restoration, in line with its canonical role in anchoring hemidesmosomes to the basement membrane and preserving the structural integrity of the interfollicular epidermal stem cell niche. Based on our results, we envision PE as an efficient and safe option to restore gene function in EB and other genodermatoses.