Tetrahedral DNA nano-PROTAC dNCL@tFNAs enhances ocular penetration and degrades nucleolin for choroidal neovascularization therapy

Despite advances, neovascular age-related macular degeneration (nAMD) and its hallmark, choroidal neovascularization (CNV), still pose significant challenges. Current anti-VEGF therapies require frequent, invasive intravitreal injections, carrying risks like intraocular infection and retinal damage, alongside substantial economic and psychological burdens. These limitations underscore the urgent need for novel therapeutic targets and less invasive drug delivery strategies. This study investigates nucleolin (NCL), a protein found to be upregulated in CNV lesions and mobilized to the endothelial cell surface upon VEGF stimulation, highlighting its critical role in angiogenesis and its potential as a therapeutic target.

Researchers developed an integrated delivery and degradation platform, dNCL@tFNAs, leveraging tetrahedral framework nucleic acids (tFNAs) to present an aptamer-based proteolysis-targeting chimera (PROTAC) specifically for nucleolin (NCL). The platform was constructed via simple Watson-Crick pairing. They evaluated dNCL@tFNAs for stability, ocular penetration, and degradation efficiency in vitro. Mechanistic studies explored the role of membrane-associated NCL in facilitating cellular uptake and subsequent degradation via the ubiquitin-proteasome pathway. In vivo studies were conducted to assess the efficacy of dNCL@tFNAs in suppressing choroidal neovascularization following a minimally invasive subconjunctival injection, alongside evaluating its safety profile.

The study identified that nucleolin (NCL) is significantly upregulated in choroidal neovascularization lesions and rapidly mobilizes to the endothelial cell surface upon VEGF stimulation. The developed dNCL@tFNAs platform demonstrated notable stability, significantly improved ocular penetration, and enhanced degradation efficiency of NCL. Mechanistic investigations revealed that membrane-associated NCL actively promotes the uptake of dNCL@tFNAs into endothelial cells. Once internalized, the PROTAC machinery engages the cytosolic ubiquitin-proteasome pathway to efficiently degrade intracellular NCL.