Focused Ultrasound Induced Blood-Brain Barrier Opening for Targeting Brain Structures and Evaluating Chemogenetic Neuromodulation
December 22nd, 2020
4.5K views
This protocol delineates steps necessary for the gene delivery through focused ultrasound blood brain barrier (BBB) opening, evaluation of the resulting gene expression, and measurement of neuromodulation activity of chemogenetic receptors through histological tests.
Overview
This protocol outlines the gene delivery process via focused ultrasound to open the blood-brain barrier (BBB) in mice, assess gene expression, and evaluate the activity of chemogenetic receptors using histological techniques.
Key Study Components
Area of Science
- Neuroscience
- Gene Therapy
- Imaging Techniques
Background
- Focused ultrasound is a non-invasive technique used for BBB opening.
- Precise targeting is crucial for effective gene delivery.
- Microbubble activation plays a key role in enhancing ultrasound-mediated delivery.
- Histological analysis is utilized to confirm gene expression and neuronal activity.
Purpose of Study
- To develop a protocol for BBB opening using focused ultrasound.
- To enable gene delivery with minimal surgical intervention.
- To evaluate neuromodulation through the expression of chemogenetic receptors.
Methods Used
- The main platform used is focused ultrasound targeted through an MRI-guided system.
- Mice are the biological model for gene delivery and neuromodulation assessment.
- No multiomics workflows are mentioned.
- Key steps include catheter insertion, ultrasound settings adjustment, and MRI sequencing.
- Histological tests are performed post-experiment to analyze gene expression.
Main Results
- The protocol facilitates reliable gene delivery and BBB opening.
- DREADD expression can be evaluated through immunostaining.
- Behaviors related to neuromodulation are recorded following clozapine N-oxide administration.
- Histological results indicate successful activation of targeted neuronal pathways.
Conclusions
- This study demonstrates a feasible approach for targeted gene delivery via ultrasound.
- Implications include enhanced methods for studying neuronal mechanisms and potential treatments for neurological disorders.
- The results underline the importance of non-invasive techniques in neuroscience research.
Frequently Asked Questions
What are the advantages of using focused ultrasound for gene delivery?
Focused ultrasound allows non-invasive BBB opening, reducing the need for surgical interventions while providing precise targeting capabilities.
How is the mouse model prepared for the experiment?
Mice are anesthetized, and a catheter is inserted into a lateral tail vein for the delivery of agents while monitoring vital signs during the procedure.
What types of data are obtained from this protocol?
Data includes imaging results from MRI, assessments of gene expression through histology, and behavioral outputs following neuromodulation.
Can this method be adapted for other models or conditions?
Yes, the protocol can be adjusted for different animal models or therapeutic agents aiming to target various neurological conditions.
What are some considerations when using this technique?
Careful monitoring of the mouse's stability and responses during the procedure is essential, along with ensuring proper coupling of the ultrasound transducer.
How does the histological analysis contribute to the study?
Histological analysis provides critical validation of gene expression and the efficacy of the neuromodulation techniques employed in the study.
Executive Industry Relevance
This protocol enables non-invasive, MRI-guided focused ultrasound for precise blood-brain barrier opening in mice, supporting targeted gene delivery and chemogenetic neuromodulation. It provides a scalable, surgery-free approach for studying neural circuit function and evaluating DREADD-based interventions in preclinical neuroscience. The method enhances target validation confidence by enabling spatially controlled transduction of large and small brain regions with millimeter precision.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of therapeutic hypotheses through spatially restricted AAV delivery to defined brain nuclei.
- Operational Value: Supports functional target validation by allowing long-term, device-free neuromodulation via chemogenetic ligands.
- Predictive Value: Improves confidence in target engagement by correlating BBB opening with mCherry immunostaining for DREADD expression.
Screening & Assay Development
- Scientific Value: Prepares validated biological systems for downstream screening by enabling consistent, localized transgene expression.
- Operational Value: Enhances assay standardization through reproducible FUS-BBBO parameters and 3D-printable targeting hardware.
- Scalability: Facilitates platform reuse across studies via adaptable mouse targeting components and microbubble preparation protocols.
Translational & Preclinical Research
- Translational Continuity: Supports preclinical validation by enabling non-invasive, repeated neuromodulation in freely moving animals using CNO.
- Mechanistic De-risking: Allows evaluation of neuronal pathway activation through histological analysis of mCherry expression post-stimulation.
- Disease-Relevant System: Models neuromodulation in brain structures like the hippocampus, relevant to cognitive and neurological disorder research.
Pipeline & Workflow Integration
The method integrates into the discovery continuum from target validation through lead identification by enabling controlled neuromodulation to assess phenotypic outcomes.
- Discovery Biology: Supports hypothesis testing by allowing precise, non-invasive control of specific neural circuits via DREADD activation.
- Screening: Describes assay readiness through quantitative MRI-based confirmation of BBB opening and histological readouts of transgene expression.
- Analytics: Highlights T1 signal enhancement and immunostaining as key readouts for comparing targeted versus non-targeted conditions.
- Translational Research: Connects to preclinical continuity through longitudinal behavioral monitoring following CNO administration.
- Enterprise Reuse: frames the protocol as a reusable capability via 3D-printable components and standardized microbubble-AAV preparation.
Operational & Enterprise Impact
- Scientific Value: Predictive confidence in target modulation through spatially controlled chemogenetic receptor expression.
- Operational Value: Standardization and reproducibility via detailed microbubble handling, catheterization, and ultrasound coupling steps.
- Strategic Value: Reduces late-stage biological risk by enabling early assessment of neuromodulation effects in intact neural circuits.
- Portfolio Impact: Informs risk-adjusted advancement by linking target engagement to behavioral and histological outcomes.
Implementation Considerations
- Requires expertise in stereotaxic targeting, venous catheterization, and ultrasound transducer coupling.
- Depends on MRI-compatible targeting hardware, focused ultrasound transducer, and microbubble activation device.
- Necessitates cross-team standardization for consistent microbubble preparation and AAV dilution across experiments.
- Involves adaptation considerations for scaling to different species or brain targets using modified 3D-printed components.
- Includes practical limitations such as microbubble stability during injection and the need for degassed gel to maintain ultrasound coupling.
Biopharma FAQs
Why does confirming lack of pedal reflex matter before catheter insertion?
Confirming lack of pedal reflex ensures adequate anesthesia depth, which is critical for stable catheter placement in the lateral tail vein and prevents movement during microbubble and virus injection.
How does isolating the independent variable of ultrasound pressure support target validation?
Isolating ultrasound pressure (0.3–0.45 MPa) allows precise control over BBB opening, enabling researchers to correlate specific pressure ranges with consistent gene delivery and DREADD expression in targeted regions.
What quantitative dependent variable measurements enable assessment of BBB opening?
T1 signal enhancement measured via fast low angle shot MRI sequence provides a quantitative readout of BBB opening, allowing correlation with microbubble delivery and transgene expression in the hippocampus and other brain regions.
Why do replication requirements matter for cross-functional collaboration in this protocol?
Replication requirements ensure that targeting coordinates, microbubble preparation, and virus dilution are consistent across experiments, enabling reliable data sharing between neuroscience, pharmacology, and histology teams.
What statistical analysis capabilities are required before implementing this method for target engagement studies?
Before implementation, teams require the ability to quantify T1 signal changes and mCherry-positive cell counts across conditions to statistically evaluate the significance of targeted versus non-targeted BBB opening and transgene expression.
Chapters in this video
0:04
Introduction
0:54
Animal Preparation
2:30
MRI‐Guided Targeting
4:35
Injection Solution Preparation
5:59
Insonation
7:10
Blood Brain Barrier (BBB) Opening Evaluation and Designer Receptors Activated Exclusively by Designer Drugs (DREADD) Stimulation
7:47
Results: BBB Opening and DREADD Expression Visualization
8:11
Conclusion
