Engineered extracellular vesicles as a targeted drug delivery system for multiple sclerosis

摘要

Abstract The ultimate goal of this F31 Ruth L. Kirchstein NRSA is to request support to address a fundamental gap in knowledge preventing engineering of efficacious drug delivery vehicles for progressive multiple sclerosis (PMS). PMS is a common, debilitating neurodegenerative disease that causes widespread demyelination in the central nervous system. There are currently no therapies that reliably remediate the advance of PMS, but an emerging strategy is to promote recovery by initiating differentiation of oligodendrocyte progenitor cells (OPCs) to oligodendrocytes, the myelin producing cells depleted in PMS. Current drug delivery techniques to achieve remyelination are either poorly efficacious or highly invasive, major impediments to clinical translation. An effective remyelinating therapeutic for PMS must cross the intact blood-brain barrier (BBB) and then target OPCs. This proposal focuses on the synthesis and testing of engineered extracellular vesicles (eEVs) as a drug delivery vehicle to accomplish these feats. Natural EVs have been shown to both target specific cells/tissues and also cross endothelial barriers. However, due to their immense functional heterogeneity, these qualities do not occur in the same EVs. Although a population of EVs that efficiently targets OPC has been identified, the best EV population and key proteins that promote BBB crossing remain unknown, preventing new biomimetic engineering strategies. To address the limitations of current therapeutics, I propose to identify and fuse subpopulations of EVs that efficiently cross the BBB and target OPCs, load them with microRNA-219, an OPC differentiating agent, to engineer a bioavailable and selective drug delivery vehicle. Building on results obtained in my preliminary data, I will carry out this project in three steps: (1) to optimize a method of fluorescence activated vesicle sorting to identify and isolate BBB-crossing EVs; (2) to elucidate the molecular mechanisms and key proteins during BBB transcytosis using a functional transwell model; and (3) to produce eEVs via fusion of endogenous EVs and loading with remyelinating therapeutics. We will quantify eEV ability to cross the BBB and target OPCs to initiate differentiation and produce myelin in vitro and in vivo. This project is focused on producing a novel therapeutic uniquely suited to PMS, but this pipeline to engineer EVs with multiple targeted functions could be applied to address drug delivery barriers for many medical problems. This project was developed in parallel with a rigorous training plan to enhance my training and technical skills in the areas of neurology, pharmacology, and translational medicine. This plan will enable my transition to independence as I focus on my long-term goal of pursuing an academic career developing neurological therapeutics. Training will exploit the university’s many resources for professional and educational development.