DNA Nanostructures as siRNA Delivery Vehicles for Alzheimer's Therapy

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PROJECT SUMMARY Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder, characterized by progressive deterioration of cognitive capacity. Currently available treatments for AD are symptomatic agents that aim to improve cognitive and behavioral symptoms without altering the underlying course of the disease or slowing disease progression. Thus, there is a necessity for disease-modifying treatment strategies for AD that can block or modify the molecular pathological steps leading to neurodegeneration. RNA interference is one such strategy that has been actively pursued for selective knockdown of AD target genes, but typically used viral vectors have preparation and safety concerns. We propose a new DNA nanotechnology approach to overcome these issues. DNA nanotechnology offers near- atomic control over building shapes and structures, eliminating heterogeneity in size of drug carriers. DNA can be functionalized with additional chemical groups that allow controllable attachment of drug molecules and protect the drug against biological degradation. Since DNA is a biological material, DNA nanostructures elicit minimal immune response when used in drug delivery, are non-toxic, biocompatible and biodegradable. Further, DNA nanostructures can enter cells without the need for a transfection agent. Our approach will use DNA polyhedra as model structures for RNA interference based treatment of AD. Specifically, we will: (1) develop DNA polyhedra with controllable attachment of small interfering RNAs (siRNAs) and incorporate 2'-O-methyl strands to enhance biostability in physiological environments, and (2) establish viability of DNA nanostructure- based drug delivery in human induced pluripotent stem cell (iPSC) derived AD model cell lines. Our proposal brings together an interdisciplinary team comprising a diverse group of researchers in chemistry, biology, and neurological disorders to provide a novel approach for RNAi treatment of AD. The proposed strategy has a number of advantages including (i) precise drug loading and quantification, (ii) biocompatibility and biodegradability, (iii) low dosage with high efficacy, and (iv) enhanced biostability to withstand physiological conditions and complex biofluids. We anticipate that our approach will provide a robust proof of concept for viable siRNA delivery by DNA nanostructures with great future potential for clinical treatment of AD.