RNA Nanoparticles for Ocular Drug Delivery to the Posterior Eye

描述（由申请人提供）：后眼疾病目前通过玻璃体内注射治疗，有时也通过全身给药。由于遇到全身毒性，不建议全身给药。与全身给药相比，玻璃体内注射是一种更有效的给药途径，但反复注射会对眼睛造成严重的副作用，并涉及较高的医疗费用。在治疗后眼疾病中，对一种更有效的给药方法的需求尚未得到满足。RNA纳米技术提供了具有DNA特征的设计简单的分子，可以用于治疗。然而，RNA纳米技术的一个主要问题是RNA分子相对不稳定，例如，RNA在体内降解，在超低浓度下进入体内后解离。近年来，从噬菌体phi29 DNA包装马达pRNA的三向结（three-way junction, 3WJ）中提取的RNA纳米颗粒被发现在体外和体内都具有热力学和化学稳定性。这些pRNA纳米颗粒，其支架完全由RNA组成，可以被修改以容纳具有不同功能的多个模块，如RNA适体、报告片段、治疗siRNA、miRNA或其他化学药物或配体作为亚基，所有这些都在同一个纳米颗粒中。我们对pRNA纳米颗粒在眼内分布的初步研究表明，其中一种pRNA纳米颗粒在体内结膜下注射后内化在视网膜细胞中。这表明，通过结膜下注射pRNA纳米颗粒作为一种有效的药物递送系统，可将rna为基础的治疗剂递送到视网膜细胞中，用于治疗后眼疾病。然而，纳米颗粒在注射后迅速从结膜下袋中清除。当前的目标

DESCRIPTION (provided by applicant): Posterior eye diseases are currently treated by intravitreal injection and sometimes by systemic drug administration. Systemic administration is not preferred because of the systemic toxicity encountered. Intravitreal injection is a more effective route of administration compared with systemic drug delivery, but repeated injections can cause severe side effects to the eye and involve high healthcare cost. There is an unmet need of a more effective drug delivery method in the treatment of posterior eye diseases. RNA nanotechnology provides molecules that has the simplicity in design with the characteristics of DNA and can be used in therapies. However, a major problem in RNA nanotechnology is that RNA molecules are relatively unstable, e.g., RNA degradation in vivo and dissociation at ultra-low concentration after administration into the body. Recently, RNA nanoparticles derived from the three-way junction (3WJ) of the pRNA of bacteriophage phi29 DNA packaging motor have been found to be thermodynamically and chemically stable both in vitro and in vivo. These pRNA nanoparticles, with their scaffolds purely made up of RNA, can be modified to harbor multiple modules with different functionalities such as RNA aptamer, reporter moiety, and therapeutic siRNA, miRNA, or other chemical drugs or ligands as subunits all in the same single nanoparticle. Our preliminary study on the distribution of pRNA nanoparticles in the eye has shown that one of these pRNA nanoparticles are internalized in the cells in the retina after subconjunctival injection in vivo. This suggests the potential of pRNA nanoparticles via subconjunctival injection as an efficient drug delivery system of RNA-based therapeutic agents to the cells in the retina for treating posterior eye diseases. However, the nanoparticle was cleared from the subconjunctival pocket quickly after the injection. The objectives of the present project are to (a) evaluate ocular delivery of pRNA nanoparticles with different module subunits via subconjunctival injection and (b) develop a sustained delivery system for these nanoparticles. A temperature sensitive gel system, which is a liquid at room temperature and solidifies at body temperature after subconjunctival injection, will be used as the sustained delivery system to enhance the retention of pRNA in the subconjunctival space. In this project, ocular delivery of pRNA nanoparticles will first be evaluated. The mechanisms of pRNA delivery to the retina after subconjunctival injection will be investigated. To overcome fast clearance after subconjunctival injection, a temperature sensitive gel system will be developed to provide sustained ocular delivery of the pRNA nanoparticles. The ultimate goal of this project is to develop a drug delivery platform for ocular drug delivery utilizing pRNA nanoparticles to provide an effective and less invasive approach than intravitreal injection.