Guanidyl-rich highly branched poly(β-amino ester)s for the delivery of dual CRISPR ribonucleoprotein for efficient large DNA fragment deletion

Gene editing technologies, particularly clustered regularly interspersed short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins, have revolutionized the ability to modify gene sequences in living cells for therapeutic purposes. Delivery of CRISPR/Cas ribonucleoprotein (RNP) is preferred over its DNA and RNA formats in terms of gene editing effectiveness and low risk of off-target events. However, the intracellular delivery of RNP poses significant challenges and necessitates the development of non-viral vectors. Our previous study has demonstrated that phenyl guanidine (PG) group modified linear poly(beta-amino ester)s (PAEs) can facilitate CRISPR/Cas9 RNP mediated gene knockout in HeLa cells. Here, we further investigated the utilization of highly branched PAEs (HPAEs) with PG groups (HPAE-PG) for efficient delivery of cytosolic protein and CRISPR/Cas9 RNP complexes, while also examining the influence of branching units and branching ratios on the delivery process. The efficiency of HPAE-PG/RNP transfection for large DNA fragment deletion was assessed using a dual sgRNA-guided approach to delete exon 80 of the human COL7A1 gene, which harbors mutations associated with dystrophic epidermolysis bullosa (DEB). Our findings demonstrate that HPAE-PG/RNP successfully induced a deletion of 56 base pairs (exon 80) within COL7A1 in both HEK cells and keratinocytes derived from recessive DEB patients. This study highlights the potential of HPAE-PG as a non-viral vector for large DNA fragment deletion, emphasizing the importance of branching factors of HPAEs in optimizing CRISPR RNP delivery for therapeutic applications in genetic disorders.