Ligase-mediated programmable genomic integration (L-PGI)

Since their discovery, CRISPR systems have been repurposed for programmable targeted genomic editing, leading to applications for gene disruption, single base editing, insertion, deletion, and manipulation of short genomic sequences. Pairing Cas9 nickase with reverse transcriptase allows applications for insertion, substitution, and deletion of short genomic sequences from an RNA template without generating double stranded breaks however this technology typically shows reduced efficacy in post mitotic cells, limiting its translatability in vivo. Here we present a novel, ligase-based method that addresses these limiations. We introduce edits through delivery and ligation of a synthetic DNA donor to genomic nicks created with Cas9 nickase and report editing activity in cell lines, primary cell cultures, and adult mice via nonviral delivery. With favorable on target outcomes compared to transcription-based editing in key cell types, good tolerability, and deliverability, ligation-mediated gene editing has the potential to further advance genomic medicine.