Selection of locally administered ocular tissue-targeting RNA aptamers using in vivo SELEX

The number of patients affected by retinal diseases is increasing worldwide, and more effective ocular drug delivery strategies are needed. Intravitreal anti-VEGF therapy has reduced the rates of visual impairment and blindness; however, frequent injections cause a significant burden on patients, resulting in poor compliance and therapeutic outcome. Thus, a targeted approach with less invasive administration could extend the dosing intervals and offer a patient-friendly alternative to the current standard of intravitreal injection. Here, in vivo Systematic Evolution of Ligands by Exponential Enrichment (SELEX) was conducted to select ocular tissue-targeting aptamers in rat using topical eye drops and subconjunctival injection. Data analysis of the sequenced aptamer pools revealed significant enrichment of Apt2 and Apt4 in ocular tissues. Their in vivo biodistribution was further evaluated using quantitative real-time PCR (qRT-PCR) at 0.5, 7, and 24 h after subconjunctival administration. Both aptamers accumulated preferentially in posterior ocular tissues, with Apt2 levels exceeding those of the control aptamer by a factor of two at 0.5 h and four at 24 h. This study demonstrates that in vivo SELEX is a viable tool to select ocular tissue-targeting aptamers from the ocular surface. This method could be utilized in the discovery of ocular targeting aptamers for therapeutic purposes and help uncover novel drug targets for various ocular disorders.