Cyclodextrin-Based Nanoparticles for Delivery of Antisense Oligonucleotides Targeting Huntingtin

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Huntington’s disease (HD) is a progressive inherited neurodegenerative disease caused by a CAG repeat expansion in the huntingtin gene, which is translated into the pathologic mutant huntingtin (mHTT) protein. Despite the great potential of HTT lowering strategies and the numerous antisense oligonucleotides (ASOs) in pre- and clinical trials, sustained silencing of mHTT has not been achieved. As a strategy to improve ASO delivery, cyclodextrin-based nanoparticles (CDs) offer a promising approach. Here, three CDs with distinct chemical structures were designed and their efficacies were compared as potential platforms for the delivery of ASO targeting HTT. Results using striatal neurons and HD patient-derived fibroblasts indicate that modified γ-CDs exhibited the best uptake efficiency and successfully downregulated mHTT at protein and allele levels. The incorporation of the brain-targeting peptide RVG into the modified γ-CDs showed greater downregulation of mHTT protein and HD-causing allele SNP1 than untargeted ones in an in vitro blood–brain barrier model. Although the ASO sequence was designed as a nonallele-specific therapeutic approach, this strategy gives an additional benefit of some mHTT selectivity. Overall, this study demonstrated the CD platform’s feasibility for delivering ASO-based therapeutics for HD treatment.

The double-charged chain γ-CDs exhibited superior internalization and knockdown efficacy compared to both β-CDs. Additionally, all three CDs evaluated were found to be non-cytotoxic in striatal neurons and HD fibroblast cells. Although designed as a non-selective approach, our strategy provides an additional benefit of some allele selectivity as demonstrated by western blotting and immunohistochemistry against the mutant polyQ tract. After the incorporation of RVG into γ-CDs, clear differences were observed between the mono- and co-culture models. RVG-targeting did not result in preferential accumulation of the nanocomplexes in the neuronal/fibroblast monoculture but did so in the co-cultured BBB model. These results may be an indication that, by direct injection into the brain, the use of untargeted CDs:ASO nanocomplexes might be sufficient to induce gene/protein knockdown. However, if systemic administration is desired, a targeting approach should be considered to overcome the BBB. 

Mendonça, M.C.P.; Sun, Y.; Cronin, M.F.; Lindsay, A.J.; Cryan, J.F.; O’Driscoll, C.M. Cyclodextrin-Based Nanoparticles for Delivery of Antisense Oligonucleotides Targeting Huntingtin. Pharmaceutics 202315, 520.

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