Long‐Term Attenuation of Vascular Hyperpermeability in a Hereditary Angioedema Mouse Model by Adenine Base Editing

ABSTRACT Background Hereditary angioedema (HAE) is a rare and potentially life‐threatening disorder caused by dysregulated kallikrein–kinin signaling and bradykinin‐induced vascular hyperpermeability. Current therapies targeting this pathway are effective but require lifelong administration, underscoring the need for durable and potentially curative interventions. Adenine base editors (ABEs), engineered from CRISPR/Cas systems, enable precise single‐nucleotide modifications with minimal genomic disruption, offering a promising strategy for long‐term gene silencing. Methods NG‐ABE8e was delivered via AAV8 or lipid nanoparticles (LNP) to disrupt the exon 2 splice donor site of Klkb1 in Serping1 +/− mice. Editing outcomes were quantified by high‐throughput sequencing; serum kallikrein levels were measured by ELISA; and vascular permeability was evaluated using Evans blue dye extravasation, fluorescent tracer leakage, and VE‐cadherin immunostaining. Safety evaluations included off‐target analysis, histopathology, serum biochemistry, activated partial thromboplastin time (aPTT), and systemic hemodynamic stability. Results AAV8‐NG‐ABE8e induced > 60% A•T‐to‐G•C conversion at the target site, promoting exon 2 skipping and reducing Klkb1 mRNA and serum kallikrein levels by > 85%, an effect sustained for at least 1 year. AAV8‐NG‐ABE8e also reversed bradykinin‐driven vascular hyperpermeability and attenuated inflammatory gene signatures. Prolongation of aPTT was observed only when circulating kallikrein levels declined below 2 μg/mL. Similarly, LNP‐mediated delivery of NG‐ABE8e mRNA resulted in > 90% reductions in Klkb1 expression and serum kallikrein levels. No evidence of significant long‐term toxicity was detected. Conclusion These findings demonstrate that, in a murine model, NG‐ABE8e–mediated disruption of Klkb1 enables durable suppression of serum kallikrein and vascular stabilization, suggesting its potential as a promising single‐intervention strategy for the treatment of HAE.