Comparative Analysis of CRISPR/Cas9 Delivery Methods in Marine Teleost Cell Lines

Gene editing technologies such as CRISPR/Cas9 have revolutionized functional genomics, yet their application in marine fish cell lines remains limited by inefficient delivery. This study compares three delivery strategies-electroporation, lipid nanoparticles (LNPs), and magnetofection using gelatin-coated superparamagnetic iron oxide nanoparticles (SPIONs)-for CRISPR/Cas9-mediated editing of the <i>ifi27l2a</i> gene in DLB-1 and SaB-1 cell lines. We evaluated transfection and editing efficiency, intracellular Cas9 localization, and genomic stability of the target locus. Electroporation achieved up to 95% editing in SaB-1 under optimized conditions, but only 30% in DLB-1, which exhibited locus-specific genomic rearrangements. Diversa LNPs enabled intracellular delivery and moderate editing (~25%) in DLB-1 but yielded only minimal editing in SaB-1, while SPION-based magnetofection resulted in efficient uptake but no detectable editing, highlighting post-entry barriers. Confocal imaging and fluorescence correlation spectroscopy suggested that nuclear localization and Cas9 aggregation may influence editing success, highlighting the importance of intracellular trafficking in CRISPR/Cas9 delivery. Our findings demonstrate that CRISPR/Cas9 delivery efficiency is cell line-dependent and governed by intracellular trafficking and genomic integrity. These insights provide a practical framework for optimizing gene editing in marine teleosts, advancing both basic research and selective breeding in aquaculture.