β-Cyclodextrin nanosponges for the ocular delivery of therapeutic Micro-RNA in a Mouse model of retinitis Pigmentosa: A proof of concept study

The exploitation of micro-RNA (miR) sequences as therapeutics has become highly attractive for the treatment of several diseases, including those still lacking effective cures such as retinitis pigmentosa (RP). Interestingly, miR-155-5p plays a role in photo-oxidative inflammation in wild-type mice and is up-regulated in rd10 mice showing peak rod degeneration, suggesting its inhibition by the corresponding anti-miR as a viable therapeutic strategy for RP. However, biomedical application of (anti-)miRs is limited by their oligonucleotide nature, suffering from low solubility and bioavailability along with a very low half-life in vivo due to enzymatic degradation. Thereby, the need for suitable delivery systems led to the development of various nanocarriers, including oligosaccharide-based polymers. In this context, we designed and prepared an innovative nanosponge (NS) with a β-cyclodextrin (β-CD) motif payload with a bridge-like molecule, the amphipathic adamantane derivative (ADM), able to establish strong interactions with both NS and the therapeutic miR, thereby delivering and eventually releasing it close to the active site. Through an in vivo study, we both validated the NS system as a useful tool for miR topical administration by eye drop formulation and the functional activity of anti-miR-155-5p in RP.