Robust genome editing via modRNA-based Cas9 or base editor in human pluripotent stem cells

Summary CRISPR systems have revolutionized biomedical research because they offer an unprecedented opportunity to explore the application of genome editing in human pluripotent stem cells (hPSCs). Due to the inherent simplicity of CRISPR systems, requiring a Cas protein and its corresponding single guide RNA (sgRNA), they are more widely adopted and used for diverse biomedical research than their predecessors (zinc finger nucleases and TALENs). However, a bottleneck of applying CRISPR systems in hPSCs is how to deliver CRISPR effectors easily and efficiently into hPSCs. Herein, we developed modified mRNA (modRNA) based CRIPSR systems that utilized Cas9 or base editor (ABE8e) modRNA for genome editing of hPSCs via simple lipid-based transfection. We have achieved 71.09% ± 9.13% and 68.53% ± 3.81% gene knockout (KO) efficiency with Cas9 modRNA and ABE8e modRNA, respectively, which is significantly higher than plasmid-based systems. In summary, we demonstrate that our non-integrating modRNA based CRISPR methods hold great promise as the more efficient and accessible techniques for genome editing of hPSCs.