Brain Gene Silencing with Cationic Amino-Capped Poly(ethylene glycol) Polyplexes

Abdullah A Alamoudi; Paula A Méndez; David Workman; Andreas G Schätzlein; Ijeoma F Uchegbu

doi:10.3390/biomedicines10092182

Brain Gene Silencing with Cationic Amino-Capped Poly(ethylene glycol) Polyplexes

Biomedicines. 2022 Sep 3;10(9):2182. doi: 10.3390/biomedicines10092182.

Authors

Abdullah A Alamoudi^{1

2}, Paula A Méndez^{1

3}, David Workman¹, Andreas G Schätzlein^{1

4}, Ijeoma F Uchegbu^{1

4}

Affiliations

¹ UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK.
² Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
³ Materials Science Research Group, Institute of Chemistry, Faculty of Exact and Natural Sciences, University of Antioquia, Calle 70 N° 52-21, A.A 1226, Medellín 050010, Colombia.
⁴ Nanomerics Ltd., 2 London Wall Place, London EC2Y 5AU, UK.

Abstract

Therapeutic gene silencing in the brain is usually achieved using highly invasive intracranial administration methods and/or comparatively toxic vectors. In this work, we use a relatively biocompatible vector: poly(ethylene glycol) star-shaped polymer capped with amine groups (4APPA) via the nose to brain route. 4APPA complexes anti- itchy E3 ubiquitin protein ligase (anti-ITCH) siRNA to form positively charged (zeta potential +15 ± 5 mV) 150 nm nanoparticles. The siRNA-4APPA polyplexes demonstrated low cellular toxicity (IC50 = 13.92 ± 6 mg mL^-1) in the A431 cell line and were three orders of magnitude less toxic than Lipofectamine 2000 (IC50 = 0.033 ± 0.04 mg mL^-1) in this cell line. Cell association and uptake of fluorescently labelled siRNA bound to siRNA-4APPA nanoparticles was demonstrated using fluorescent activated cell sorting (FACS) and confocal laser scanning microscopy (CLSM), respectively. Gene silencing of the ITCH gene was observed in vitro in the A431 cell line (65% down regulation when compared to the use of anti-ITCH siRNA alone). On intranasal dosing with fluorescently labelled siRNA-4APPA polyplexes, fluorescence was seen in the cells of the olfactory bulb, cerebral cortex and mid-brain regions. Finally, down regulation of ITCH was seen in the brain cells (54 ± 13% ITCH remaining compared to untreated controls) in a healthy rat model, following intranasal dosing of siRNA-4APPA nanoparticles (0.15 mg kg^-1 siRNA twice daily for 3 days). Gene silencing in the brain may be achieved by intranasal administration of siRNA- poly(ethylene glycol) based polyplexes.

Keywords: brain; gene silencing; intranasal; nanoparticles; polyethylene glycol (PEG); siRNA delivery.

Grants and funding

This research was funded by a scholarship from the Saudi Arabia government to A.A.A. (Reference number = K963. The work was also part funded by the Engineering and Physical Sciences Research Council (Grant Reference = EP/L024748/1).