DNA-free in vivo base editing in zebrafish embryos and in the inner ear of live mice using RNP delivery of BE3. ( a ) On-target genome editing in zebrafish harvested 4 days after injection of BE3 complexed with indicated sgRNA. Values and error bars reflect mean±s.d. of three injected and three control zebrafish. Controls were injected with BE3 complexed with an unrelated sgRNA. ( b ) Schematic showing in vivo injection of BE3:sgRNA complexes encapsulated into cationic lipid nanoparticles. ( c ) Base editing of cytosine residues in the base editor window at the VEGFA site 2 genomic locus. ( d ) On-target editing at each cytosine in the base-editing window of the VEGFA site 2 target locus. ( c , d ) Values and error bars reflect mean±s.e.m. of three mice injected with sgRNA targeting VEGFA site 2, three uninjected mice and one mouse injected with unrelated sgRNA.