Abstract 7247: Exosome-mediated delivery of RNA and DNA: Enhanced efficiency with polycationic PEI-PEG
Authors: Moholkar Disha Nagesh , Kandimalla Raghuram , Wallen Margaret , Jeyabalan Jeyaprakash , Spencer Wendy , Aqil Farrukh , Gupta Ramesh C. 
Published: March 2024

Abstract
Emerging advances in gene therapy over the past few decades have revolutionized biomedical research. Our lab has pioneered bovine milk and colostrum-derived exosomes (Exo) and devised a nanoplatform for nucleic acid delivery achieving targetability with folic acid (FA) functionalization. We showed that bovine colostrum exosomes complexed with high MW polyethyleneimine (PEI-60K) can efficiently delivery siRNA and plasmid DNA (pDNA) in vitro and in vivo. We hypothesize that lower MW PEI may improve transfection efficiency and enhance oral uptake of EPM-siRNA, in addition to presumably higher degradability in a cellular system. We now report that exosomes and PEI of lower MW (25K)-PEG copolymer is as effective or more effective for delivery of siRNA and pDNA than PEI-60K. Incubation of exosomes, PEI-25K and siRNA in the presence of 5’-32P-labeled siRNA as a tracer showed high siRNA entrapment (&gt;90%) based on the distribution of the radioactivity in EPM-siRNA precipitate compared with the supernatant. The efficacy of the EPM matrix is gene specific. As treatment of A549 lung cancer cells with EPM-(PEI-60K)-siKRAS showed 60% knockdown of target KRAS gene, which was enhanced to 70% by EPM-(PEI-25K)-siKRAS. Moreover, p53-pDNA delivered by EPM-25K resulted in nearly 2-fold higher expression of p53 in p53-null H1299 lung cancer cells compared with EPM-60K. However, still lower MW PEI (PEI-15K) diminished the transfection efficiency (36% KRAS knockdown). EPM formulated with PEI-60K and 25K had similar effect on cell viability of HEK293 cells. Upon in vivo testing, EPM-25K loaded with siKRAS and functionalized with folic acid (FA) showed time-dependent growth inhibition of A549-innoculated orthotopic lung tumors in NOD Scid mice eliciting 76% (p&lt;0.01) tumor growth inhibition. The tumor inhibition was accompanied with 50% (p&lt;0.05) knockdown of the target gene in the tumor tissue, while the adjacent lung tissue showed no modulation. The anti-tumor efficacy of siKRAS delivered by FA-functionalized EPM-25K is the same or somewhat higher than the efficacy reported previously with FA-functionalized EPM-60K.In conclusion, based on our in vitro and in vivo results, lower MW PEI (PEI-25K) is a suitable alternative for PEI-60K with boosted efficacy in terms of knockdown of KRAS. Our proposed technology offers a platform to advance and overcome the obstacles in the clinical translation of gene therapy.
Funding: Work supported from funds provided by 3P Biotechnologies and in part Agnes Brown Duggan Funds. Disha Nagesh Moholkar is supported by IPIBS Fellowship, University of Louisville.
Citation Format: Disha Nagesh Moholkar, Raghuram Kandimalla, Margaret Wallen, Jeyaprakash Jeyabalan, Wendy Spencer, Farrukh Aqil, Ramesh C. Gupta. Exosome-mediated delivery of RNA and DNA: Enhanced efficiency with polycationic PEI-PEG [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7247.