Evaluation of Tris[2-(Acryloyloxy)Ethyl]Isocyanurate Cross-Linked Polyethylenimine as Antisense Morpholino Oligomer Delivery Vehicle in Cell Culture and Dystrophic mdx Mice

Hyperbranched poly(ester amine)s (PEAs) based on tris[2-(acryloyloxy)ethyl]isocyanurate (TAEI) cross-linked low-molecular-weight polyethylenimine (Mw: 0.8k/1.2k/2.0k) have been evaluated for delivering antisense phosphorodiamidate morpholino oligomer (PMO) in vitro and in vivo in the dystrophic mdx mouse. The results show that the PEAs constructed with polyethylenimine (PEI) 2.0k (C series) improved PMO delivery more efficiently than those constructed with PEI 0.8k (A series) or 1.2k (B series) in a GFP reporter-based C2C12 mouse myoblast culture system. The highest efficiency of exon-skipping in vitro with the PMO oligonucleotide targeting human dystrophin exon 50 was obtained when the PEA C12 [TAEI-PEI 2.0k (1:2)] was used. Nearly all of the PEAs improved dystrophin expression in mdx mice by local injection with a 2–4-fold increase when compared with PMO alone. Improved transfection efficiency and lower toxicity indicate the potential of the biodegradable PEA polymers as safe and efficient PMO delivery vectors for in vivo applications.