Nanoparticle-mediated Delivery of Anti-PU.1 Sirna via Localized Intracisternal Administration Reduces Neuroinflammation.

Neuroinflammation is a hallmark of neurodegenerative disorders including Alzheimer's Disease (AD). Microglia, the brain's immune cells, express many of the AD-risk loci identified in genome wide association studies and present a promising target for anti-inflammatory RNA therapeutics but are difficult to transfect with current methods. Here, we examined several lipid nanoparticle (LNP) formulations and identified a lead candidate that supports efficient RNA delivery in cultures of human stem cell-derived microglia-like cells (iMGLs) and animal models of neuroinflammation. The lead microglia LNP (MG-LNP) formulation showed minimal toxicity and improved delivery efficiency to inflammatory iMGLs, suggesting a preference for delivery into activated microglia. Systemic injection of the MG-LNP formulation generated wide-spread expression of the delivered reporter construct in all organs whereas local intracisternal injection directly into the cerebrospinal fluid led to preferential expression in the brain. We showed that LNP-mediated delivery of siRNA targeting the PU.1 transcription factor, a known AD-risk locus, successfully reduced PU.1 levels in iMGLs and reduced neuroinflammation in mice injected with LPS and in CK-p25 mice that mimic the chronic neuroinflammation seen in AD patients. Our LNP formulation represents an effective RNA delivery vehicle when applied intrathecally and can be broadly utilized to test potential neuroinflammation-directed gene therapies. This article is protected by copyright. All rights reserved.