Efficient human genome editing using SaCas9 ribonucleoprotein complexes

: Genome editing using RNA-guided nucleases in their ribonucleoprotein (RNP) form represents a promising strategy for gene modification and therapy because they are free of exogenous DNA integration and have reduced toxicity in vivo and ex vivo. However, genome editing by Cas9 nuclease from Staphylococcus aureus (SaCas9) has not been reported in its RNP form, which recognizes a longer protospacer adjacent motif (PAM), 5'-NNGRRT-3', compared with Streptococcus pyogenes Cas9 (SpCas9) of 5'-NGG-3' PAM. Here, SaCas9-RNP-mediated genome editing is reported in human cells. The SaCas9-RNP displayed efficient genome editing activities of enhanced green fluorescent protein (EGFP) coding gene as well as three endogenous genes (OPA1, RS1, and VEGFA). Further, SaCas9-RNP is successfully implemented to correct a pathogenic RS1 mutation for X-linked juvenile retinoschisis. It is also shown that off-target effects triggered by SaCas9-RNP are undetectable by targeted deep sequencing. Collectively, this study demonstrates the potential of SaCas9-RNP-mediated genome editing in human cells, which could facilitate genome-editing-based therapy.