Noninvasive focused ultrasound-mediated delivery of rAAV9-EGFP vectors for neuronal targeting in rats

Rui Wang; Jiayi Li

doi:10.1016/j.neuroimage.2024.120630

Noninvasive focused ultrasound-mediated delivery of rAAV9-EGFP vectors for neuronal targeting in rats

Neuroimage. 2024 May 11:294:120630. doi: 10.1016/j.neuroimage.2024.120630. Online ahead of print.

Authors

Rui Wang¹, Jiayi Li²

Affiliations

¹ Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China; Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, Sichuan, China. Electronic address: ruiwang@scu.edu.cn.
² Cancer Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.

PMID: 38740226
DOI: 10.1016/j.neuroimage.2024.120630

Abstract

Objective: To evaluate the synergistic potential of Focused Ultrasound (FUS) in conjunction with microbubbles (MB) and recombinant adeno-associated virus serotype 9 (rAAV9) vectors for targeted gene delivery to neuronal cells in rats, optimizing gene expression conditions and assessing any adverse effects.

Methods: The parameters for permeability enhancement of the rat's blood-brain barrier (BBB) were established using FUS+MB, with MRI scans and Evans Blue (EB) dye assisting in the evaluation. Rats underwent FUS-mediated transfection using rAAV9-Syn-EGFP vectors produced via a triple-transfection in HEK293T cells. Following this, the uptake and expression of GFP in targeted brain regions were evaluated using confocal fluorescence microscopy at various time intervals. Inflammatory responses post-FUS treatment were tracked by observing levels of GFAP, a marker for astrocytic activation, and TNF-α, a pro-inflammatory cytokine. Motor behavior effects post-intervention were gauged using the Rotarod test across multiple groups over a span of four weeks.

Results: FUS+MB affected BBB permeability, with optimal results at 4 W for 200 s showing 85 % permeability and evident Gd-DTPA leakage. Settings beyond these resulted in tissue damage. Control groups exhibited a basal GFP expression of 2 % ± 0.5 %, whereas FUS+MB with rAAV-EGFP injections substantially increased GFP expression to about 67 % ± 6 % in targeted neurons. This GFP expression peaked at three weeks post-treatment and remained evident six months later. Following FUS treatment, both GFAP and TNF-α levels underwent fluctuations before eventually nearing their baseline values. The Rotarod test revealed no significant behavioral differences post-treatments among the groups.

Conclusions: Combining FUS+MB with rAAV offers an innovative approach to enhance therapeutic delivery to the central nervous system (CNS) by transiently adjusting BBB permeability.

Keywords: Blood-brain barrier; Focused ultrasound; Gene therapy; Inflammatory response; Recombinant adeno-associated virus.