Direct Cytosolic Delivery of siRNA Conjugates: A Paradigm in Antiangiogenic Therapy for Choroidal Neovascularization

Small interfering RNA (siRNA) has garnered tremendous interest as a potential therapeutic tool because of its intriguing gene-silencing ability. Toward the success in the manufacture of siRNA therapeutics for the potential treatment of choroidal neovascularization (CNV), siRNA conjugated with dual functional units of membrane-penetrating heptafluoropropyl and age-related macular degeneration-targeting cyclic Arg-Gly-Asp (RGD) peptide was attempted for transcellular transportation into the cell interiors. Of note, cyclic RGD allowed selective affinities toward the angiogenic endothelial cells in the pathological CNV. Noteworthy is the functional heptafluoropropyl group, due to its tempting lipophobic and hydrophobic properties, stimulating energy-independent transcellular trafficking behaviors to the cytoplasm directly from the extracellular compartments, namely, the nonendocytotic pathway. The behaviors manage to avoid the well-acknowledged drawback of endolysosomal entrapment, which is deemed to be the critical threat to the biovulnerable genomic therapeutics, thereby contributing to potent gene knockdown at the affected cells. Aiming for treatment of CNV, the siRNA duo was schemed with appropriate chemistry-based modifications for the targeted knockdown of both angiogenic VEGF-A and VEGF-R2. Subsequent investigations verified the potent reduction of vascular leakage, and our proposed siRNA duo accomplished a significant reduction of 67.3% in the mean area of the CNV lesion. Bioinformatic analysis has unveiled a multitude of therapeutic benefits conferred by anti-VEGF therapy, extending beyond the mere inhibition of angiogenesis, including the regulated leukocyte transendothelial migration, retinol metabolism, and estrogen signaling pathways. Hence, our proposed chemistry represents an interesting siRNA conjugate strategy accomplishing direct intracellular transportation of macromolecular biological payloads to the cytosol. Hence, this proposed fluorination strategy should be highlighted to encourage the development of appropriate prodrug chemistry in pursuit of transcellular trafficking of membrane-impermissible and biovulnerable biotherapeutics.