Sonothermogenetics for noninvasive and cell-type specific deep brain neuromodulation

Abstract

Background: Critical advances in the investigation of brain functions and treatment of brain disorders are hindered by our inability to selectively target neurons in a noninvasive manner in the deep brain.Objective: This study aimed to develop sonothermogenetics for noninvasive, deep-penetrating, and celltype-specific neuromodulation by combining a thermosensitive ion channel TRPV1 with focused ultrasound (FUS)-induced brief, non-noxious thermal effect. Methods: The sensitivity of TRPV1 to FUS sonication was evaluated in vitro. It was followed by in vivo assessment of sonothermogenetics in the activation of genetically defined neurons in the mouse brain by two-photon calcium imaging. Behavioral response evoked by sonothermogenetic stimulation at a deep brain target was recorded in freely moving mice. Immunohistochemistry staining of ex vivo brain slices was performed to evaluate the safety of FUS sonication. Results: TRPV1 was found to be an ultrasound-sensitive ion channel. FUS sonication at the mouse brain in vivo selectively activated neurons that were genetically modified to express TRPV1. Temporally precise activation of TRPV1-expressing neurons was achieved with its success rate linearly correlated with the peak temperature within the FUS-targeted brain region as measured by in vivo magnetic resonance thermometry. FUS stimulation of TRPV1-expressing neurons at the striatum repeatedly evoked locomotor behavior in freely moving mice. FUS sonication was confirmed to be safe based on inspection of neuronal integrity, inflammation, and apoptosis markers. Conclusions: This noninvasive and cell-type-specific neuromodulation approach with the capability to stimulate deep brain has the promise to advance the study of the intact nervous system and uncover new ways to treat neurological disorders.

Incisionless targeted adeno-associated viral vector delivery to the brain by focused ultrasound-mediated intranasal administration

“…We performed a comparative analysis of FUSIN, DI, FUS-BBBD, and IN delivery of AAV5-hSyn-EGFP. The AAV dose used in DI was limited by the injection volume (1.2 µL), 26 , 27 and the injection was targeted at the mouse cortex. The AAV dose for all other methods was 24 μL.…”

“…Each mouse in the DI group was injected with 1.2 μL of AAVs following the established protocol. 26 , 27 …”

Non-invasive optogenetics with ultrasound-mediated gene delivery and red-light excitation

“…Despite its scalability, ATAC has limited temporal control over the stimulation duration, which depends on the circulation time of CNO. Ultrasound has also been used as a thermal stimulus following direct injection of lentivirus-encoded thermally-sensitive TRPV1 ion channels in sonothermogenetics [34]. Sonothermogenetic activation evoked locomotor behavior in freely moving mice, only when local temperature during high-duty-cycle sonication exceeded 42 C. However, this approach required either anesthesia or implantation of a construct bearing the FUS transducer onto the mouse skull, hindering application in larger species or humans.…”

Binary acoustic metasurfaces for dynamic focusing of transcranial ultrasound

“…It can non-invasively penetrate through the skull bone and focus on targeted brain locations with millimeter precision. tFUS at low intensity levels has been used for neuromodulation by targeting different parts of the brain ( Legon et al, 2014 ; Ibsen et al, 2015 ; Qiu et al, 2020 ; Yang et al, 2021 ; Darmani et al, 2022 ). tFUS combined with microbubbles can non-invasively, locally, and reversibly disrupt the blood-brain barrier for brain drug delivery ( Chen and Konofagou, 2014 ; Lipsman et al, 2018 ; Chen et al, 2021 ; Hu et al, 2022a ) or brain tumor-derived molecular biomarker release ( Zhu et al, 2018 ; Meng et al, 2021 ; Pacia et al, 2022 ).…”