Lipid nanoparticle-based non-viral in situ gene editing of congenital ichthyosis-causing mutations in human skin models

Autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare, highly debilitating skin disorders that 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 wildtype 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 desorption electrospray ionization (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.