Non-viral in situ gene editing effectively and safely rescues congenital ichthyosis-causing mutations in human skin

Autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare, highly debilitating skin disorders which significantly impair patients’ quality of life and lack any effective treatment options. Here, we report clinically-relevant in situ correction of the most common ARCI-causing mutation TGM1 c.877-2A>G, a splice-site aberration, in human disease models. Targeted skin barrier modulation followed by topical application of the cytosine base editor eTD packaged into lipid nanoparticles yielded functional restoration of ~30% of wild-type transglutaminase 1 activity in skin tissue. Toxicity studies and comprehensive off-target analysis demonstrated an excellent safety profile even after repeated application, without systemic distribution of the lipid nanoparticles or the genetic cargo as determined via highly-sensitive methods including DESI metabolic imaging. This study presents comprehensive preclinical data on the feasibility of in situ gene correction of genodermatoses-causing mutations showcasing its therapeutic potential and paving the way for curative next-generation treatments for severe genetic skin diseases.