Targeted Exosomal Delivery of siRNA Therapeutics for Neuroinflammatory Diseases

Technical Abstract Neurodegenerative disorders affect over 40 million people worldwide and most, if not all, are mediated by inflammation. Even though several drugs have recently been approved by the FDA for treating neurological disorders including Alzheimer's disease (AD), their efficacy as AD therapeutics has not been realized as extremely low levels of the drug reach the brain. The goal of this Phase I project is to develop an effective targeted delivery system for siRNA against NFκB expression (siNFκB) to mitigate neuroinflammatory diseases. We have recently shown that siRNA entrapped in bovine colostrum-derived exosomes and polyethyleneimine matrix (EPM) can effectively deliver siRNA to reduce target gene expression. We will apply our extensive experience in exosomes, siRNA therapeutics and inflammatory responses for efficient, targeted delivery of siNFκB to the microenvironment of the brain where progressive increase in inflammation ultimately leads to manifestation of neuroinflammatory diseases including AD. We hypothesize that EPM-siNFκB formulations administered via a novel trans-spinal (t.s.) route can effectively deliver siNFκB to the brain and knockdown the inflammatory regulator NFκB and attenuate corresponding disease markers. We also hypothesize that use of smaller exosomes (smExo) (average size 45 nm) coupled with folic acid (FA)-functionalization can enhance the brain delivery presumably due to more efficient crossing of the blood brain barrier and high expression of folate receptor-α (FRα) in the brain, respectively. Our hypotheses are supported by high siRNA entrapment (>90%) in the EPM, protection of EPM-siRNA from enzymatic degradation, higher knockdown of NFκB in murine cells than conventional reagents, higher brain accumulation of smEPM-siRNA in mice treated via t.s. route compared with the traditional routes, intravenously and intranasally, and FA-functionalization of exosomes for brain targeting. Innovation in this project lies in the use of bovine colostrum powder - an abundant and cost-effective source of native exosomes, use of smaller exosomes and FA-functionalization coupled with t.s. administration. Investigators experienced in exosomes, drug delivery, siRNA therapeutics and animal models, leveraging extensive experience of Dr. Robert Friedland in AD research, will pursue the following specific aims: Aim 1. Optimize delivery of siNFκB using FA-functionalized exosomal vector in vitro and in vivo. Murine cell lines bearing WT sequences of NFκB will be used to identify effective siNFκB sequences based on NFκB knockdown. Aim 2. In vivo efficacy of brain-targeted FA-smEPM-siNFκB. The lead formulation from Aim 1 will be tested for efficacy in murine models of AD. Therapeutic benefit will be based on knockdown of NFκB in the target (cortex and hippocampus) and non-target tissues, related histopathological and AD biomarker changes, and assessment of behavioral endpoints. This project will provide proof-of-principle for inhibition of neuroinflammation by targeted t.s. delivery of siNFκB. In Phase II, we will compare inhibition of other targets such as BACE1, a key target for AD, alone and in combination with NFκB using multiple rodent AD models to identify the optimal gene target(s) for this disease.