Rhodopsin Genomic Loci DNA Nanoparticles Improve Expression and Rescue of Retinal Degeneration in a Model for Retinitis Pigmentosa

The use of gene therapy may allow replacement of the defective gene. Minigenes, such as cDNAs, are often used. However, these may not express normal physiological genetic profiles due to lack of crucial endogenous regulatory elements. We constructed DNA nanoparticles (NPs) that contain either the mouse or human full-length rhodopsin genomic locus, including endogenous promoters, all introns, and flanking regulatory sequences of the 15-16 kb genomic rhodopsin DNA inserts. We transduced the NPs into primary retinal cell cultures from the rhodopsin knockout (RKO) mouse in vitro and into the RKO mouse in vivo and compared the effects on different functions to plasmid cDNA NP counterparts that were driven by ubiquitous promoters. Our results demonstrate that genomic DNA vectors resulted in long-term high levels of physiological transgene expression over a period of 5 months. In contrast, the cDNA counterparts exhibited low levels of expression with sensitivity to the endoplasmic reticulum (ER) stress mechanism using the same transgene copy number both in vitro and in vivo. This study demonstrates for the first time the transducing of the rhodopsin genomic locus using compacted DNA NPs.