ABSTRACT
Sonogenetics is a promising strategy allowing the noninvasive and selective activation of targeted neurons in deep brain regions; nevertheless, its therapeutic outcome for neurodegeneration diseases that need long-term treatment remains to be verified. We previously enhanced the ultrasound (US) sensitivity of targeted cells by genetic modification with an engineered auditory-sensing protein, mPrestin (N7T, N308S). In this study, we expressed mPrestin in the dopaminergic neurons of the substantia nigra in Parkinson's disease (PD) mice and used 0.5 MHz US for repeated and localized brain stimulation. The mPrestin expression in dopaminergic neurons persisted for at least 56 days after a single shot of adeno-associated virus, suggesting that the period of expression was long enough for US treatment in mice. Compared to untreated mice, US stimulation ameliorated the dopaminergic neurodegeneration 10-fold and mitigated the PD symptoms of the mice 4-fold, suggesting that this sonogenetic strategy has the clinical potential to treat neurodegenerative diseases.
Subject(s)
Parkinson Disease , Animals , Disease Models, Animal , Dopamine , Dopaminergic Neurons , Mice , Mice, Inbred C57BL , Parkinson Disease/genetics , Parkinson Disease/therapy , Substantia NigraABSTRACT
Sonogenetics is a promising approach for in vivo neuromodulation using ultrasound (US) to non-invasively stimulate cells in deep tissue. However, sonogenetics requires accurate transduction of US-responsive proteins into target cells. Here, we introduce a non-invasive and non-viral approach for intracerebral gene delivery. This approach utilizes temporary ultrasonic disruption of the blood-brain barrier (BBB) to transfect neurons at specific sites in the brain via DNA that encodes engineered US-responsive protein (murine Prestin (N7T, N308S))-loaded microbubbles (pPrestin-MBs). Prestin is a transmembrane protein that exists in the mammalian auditory system and functions as an electromechanical transducer. We further improved the US sensitivity of Prestin by introducing specific amino acid substitutions that frequently occur in sonar species into the mouse Prestin protein. We demonstrated this concept in mice using US with pPrestin-MBs to non-invasively modify and activate neurons within the brain for spatiotemporal neuromodulation. Method: MBs composed of cationic phospholipid and C3F8 loaded with mouse Prestin plasmid (pPrestin) via electrostatic interactions. The mean concentration and size of the pPrestin-MBs were (16.0 ± 0.2) × 109 MBs/mL and 1.1 ± 0.2 µm, respectively. SH-SY5Y neuron-like cells and C57BL mice were used in this study. We evaluated the gene transfection efficiency and BBB-opening region resulting from pPrestin-MBs with 1-MHz US (pressure = 0.1-0.5 MPa, cycle = 50-10000, pulse repetition frequency (PRF): 0.5-5 Hz, sonication time = 60 s) using green fluorescence protein (Venus) and Evans blue staining. Results: The maximum pPrestin expression with the highest cell viability occurred at a pressure of 0.5 MPa, cycle number of 5000, and PRF of 1 Hz. The cellular transfection rate with pPrestin-MBs and US was 20.2 ± 2.5%, which was 1.5-fold higher than that of commercial transfection agents (LT-1). In vivo data suggested that the most profound expression of pPrestin occurred at 2 days after performing pPrestin-MBs with US (0.5 MPa, 240 s sonication time). In addition, no server erythrocyte extravasations and apoptosis cells were observed at US-sonicated region. We further found that with 0.5-MHz US stimulation, cells with Prestin expression were 6-fold more likely to exhibit c-Fos staining than cells without Prestin expression. Conclusion: Successful activation of Prestin-expressing neurons suggests that this technology provides non-invasive and spatially precise selective modulation of one or multiple specific brain regions.
Subject(s)
Brain/metabolism , Genetic Therapy/instrumentation , Protein Engineering/methods , Ultrasonic Waves/adverse effects , Ultrasonography/instrumentation , Animals , Auditory Pathways/metabolism , Auditory Pathways/physiopathology , Blood-Brain Barrier/metabolism , Cations/metabolism , DNA/metabolism , Gene Transfer Techniques/instrumentation , Mice , Mice, Inbred C57BL , Microbubbles , Molecular Motor Proteins/metabolism , Neurotransmitter Agents/pharmacology , Plasmids/metabolism , Sonication , Targeted Gene Repair/methods , TransfectionABSTRACT
Biomolecules that respond to different external stimuli enable the remote control of genetically modified cells. We report herein a sonogenetic approach that can manipulate target cell activities by focused ultrasound stimulation. This system requires an ultrasound-responsive protein derived from an engineered auditory-sensing protein prestin. Heterologous expression of mouse prestin containing two parallel amino acid substitutions, N7T and N308S, that frequently exist in prestins from echolocating species endowed transfected mammalian cells with the ability to sense ultrasound. An ultrasound pulse of low frequency and low pressure efficiently evoked cellular calcium responses after transfecting with prestin(N7T, N308S). Moreover, pulsed ultrasound can also noninvasively stimulate target neurons expressing prestin(N7T, N308S) in deep regions of mouse brains. Our study delineates how an engineered auditory-sensing protein can cause mammalian cells to sense ultrasound stimulation. Moreover, our sonogenetic tools will serve as new strategies for noninvasive therapy in deep tissues.
