Lipopeptide-mediated delivery of CRISPR/Cas9 ribonucleoprotein complexes for gene editing and correction

CRISPR/Cas gene editing is a highly promising technology for the treatment and even potential cure of genetic diseases. One of the major challenges for its therapeutic use is finding safe and effective vehicles for intracellular delivery of the CRISPR/Cas9 ribonucleoprotein (RNP) complex. In this study, we tested and characterized a series of novel fatty acid-modified versions of a previously reported Cas9 RNP carrier, consisting of a complex of the cell-penetrating peptide (CPP) LAH5 with Cas9 RNP and homology-directed DNA repair templates. Comparative experiments demonstrated that RNP/peptide nanocomplexes showed various improvements depending on the type of fatty acid modification. These improvements included enhanced stability in serum, improved membrane disruption capability and increased transfection efficacy. Cas9 RNP/oleic acid LAH5 peptide nanocomplexes showed the overall best performance for both gene editing and correction. Moreover, Cas9 RNP/oleic acid LAH5 nanocomplexes significantly protected the Cas9 protein cargo from enzymatic protease digestion. In addition, in vivo testing demonstrated successful gene editing after intramuscular administration. Despite the inherent barriers of the tightly organized muscle tissues, we achieved approximately 10 % gene editing in the skeletal muscle tissues when targeting the CAG-tdTomato locus in the transgenic Ai9 Cre-LoxP reporter mouse strain and 7 % gene editing when targeting the Ccr5 gene, without any observable short-term toxicity. In conclusion, the oleic acid-modified LAH5 peptide is an effective delivery platform for direct Cas9/RNP delivery, and holds great potential for the development of new CRISPR/Cas9-based therapeutic applications for the treatment of genetic diseases.