Preclinical Cardiac Electrophysiology Assessment by Dual Voltage and Calcium Optical Mapping of Human Organotypic Cardiac Slices
June 16th, 2020
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This protocol describes the procedure for sectioning and culturing human cardiac slices for preclinical drug testing and details the use of optical mapping for recording transmembrane voltage and intracellular calcium signals simultaneously from these slices.
Overview
This protocol describes the procedure for sectioning and culturing human cardiac slices for preclinical drug testing. It details the use of optical mapping for recording transmembrane voltage and intracellular calcium signals simultaneously from these slices.
Key Study Components
Area of Science
- Cardiac physiology
- Preclinical drug testing
- Optical mapping techniques
Background
- This protocol utilizes donor human hearts for physiological drug testing.
- It employs voltage and calcium dyes for simultaneous characterization of cardiac action potentials and intracellular calcium transients.
- The setup includes a tissue bath and a perfusion system.
- Temperature and oxygenation are critical for maintaining tissue viability.
Purpose of Study
- To provide a reliable method for studying human cardiac tissue.
- To enable the simultaneous recording of voltage and calcium signals.
- To facilitate preclinical testing of cardiac drugs.
Methods Used
- Preparation of human cardiac slices using a vibratome.
- Use of a polydimethylsiloxane gel layer in the tissue bath.
- Circulation of recovery solution at controlled temperature and oxygen levels.
- Optical mapping with CMOS cameras and specific LED light sources.
Main Results
- Successful simultaneous recording of transmembrane voltage and intracellular calcium signals.
- Demonstrated viability of human cardiac slices for drug testing.
- Validated the optical mapping setup for future studies.
- Provided a detailed protocol for researchers to replicate.
Conclusions
- This protocol enhances the ability to study human cardiac physiology.
- It offers a valuable tool for preclinical drug testing.
- Future studies can build on this methodology for further insights.
Frequently Asked Questions
What is the significance of using human cardiac slices?
Using human cardiac slices allows for more accurate physiological responses in drug testing compared to animal models.
How are the cardiac slices prepared?
Cardiac slices are prepared using a vibratome after the heart is placed in a cardioplegia solution.
What is optical mapping?
Optical mapping is a technique used to visualize electrical activity and calcium transients in cardiac tissue using fluorescent dyes.
What temperature is required for the recovery solution?
The recovery solution should be maintained at 37 degrees Celsius.
What types of dyes are used in this protocol?
Voltage-sensitive and calcium indicator dyes are used for simultaneous recording.
Can this protocol be used for other types of tissues?
While this protocol is designed for cardiac tissue, similar methods may be adapted for other tissues with appropriate modifications.
Executive Industry Relevance
Human cardiac slice models bridge the translational gap between animal studies and clinical trials by preserving native human tissue architecture, enabling more predictive preclinical assessment of cardiac drug effects. This approach supports mechanistic de-risking of electrophysiological liabilities early in discovery, improving go/no-go decisions and reducing late-stage attrition. The high-throughput capacity from single-heart slice yield enhances portfolio triage efficiency for lead optimization campaigns.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables direct interrogation of drug effects on human cardiac electrophysiology and calcium handling, clarifying target engagement and pathway modulation.
- Operational Value: Provides quantitative, simultaneous voltage and calcium readouts for functional target validation in physiologically relevant human tissue.
Screening & Assay Development
- Scientific Value: Generates standardized, reproducible electrophysiological and calcium transient metrics for assay readiness in compound screening.
- Operational Value: Supports high-throughput preparation of hundreds of slices per heart, enabling multi-concentration and combination drug testing under controlled conditions.
Translational & Preclinical Research
- Scientific Value: Maintains multicellular structure, cell-cell coupling, and extracellular matrix, ensuring disease-relevant human tissue responses for preclinical continuity.
- Operational Value: Allows acute and chronic drug effect studies in the same model, supporting longitudinal safety and efficacy profiling.
Pipeline & Workflow Integration
The method integrates into early discovery for target validation, feeds into screening cascades for lead identification, and supports preclinical assessment by providing human-relevant electrophysiological data that informs risk-adjusted advancement decisions.
- Discovery Biology: Supports hypothesis testing of cardiac ion channel and calcium handling targets through direct measurement of action potentials and transients in human tissue.
- Screening: Delivers quantitative, simultaneous optical mapping outputs that enable reliable compound effect comparison across concentrations and combinations.
- Analytics: Provides conduction velocity, action potential duration, calcium transient decay, and rise time metrics that help teams compare drug-induced electrophysiological changes.
- Translational Research: Connects discovery findings to preclinical validation by using the same human tissue model across stages, enhancing mechanistic continuity.
- Enterprise Reuse: Establishes a reusable platform for iterative drug testing, reducing reliance on disparate animal models and increasing data consistency across projects.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in target validation by reducing species-specific mechanistic ambiguity in cardiac electrophysiology.
- Operational Value: Ensures standardization and reproducibility through controlled tissue preparation, dye loading, and optical mapping parameters.
- Strategic Value: Improves capital efficiency by enabling early detection of cardiac liabilities, reducing costly late-stage failures.
- Portfolio Impact: Facilitates risk-adjusted prioritization of compounds based on human-relevant electrophysiological safety profiles.
Implementation Considerations
- Requires expertise in human tissue handling, vibratome sectioning, and optical mapping system setup.
- Dependent on perfusion systems with precise temperature and oxygenation control, CMOS cameras, and specific LED excitation sources.
- Necessitates cross-team standardization of slice preparation, dye protocols, and signal conditioning procedures for reproducible results.
- Must account for tissue variability across donor hearts and regional differences in slice electrophysiological properties.
- Limited by slice viability duration in culture, requiring timely experimentation to maintain physiological fidelity.
Biopharma FAQs
Why does simultaneous voltage and calcium optical mapping matter for target validation?
Simultaneous recording of transmembrane potentials and intracellular calcium dynamics enables direct assessment of drug effects on excitation-contraction coupling in human tissue, providing mechanistic insight into target engagement and functional consequences beyond surrogate markers.
How does isolating the independent variable (drug concentration) fit the discovery pipeline?
Controlling drug concentration as the independent variable allows precise dose-response characterization of electrophysiological effects, supporting lead optimization and structure-activity relationship analysis in early discovery.
What quantitative dependent variable measurements enable predictive confidence?
Measurements such as conduction velocity, action potential duration, calcium transient decay constant, and rise time provide objective, quantifiable endpoints for comparing drug effects and establishing structure-safety relationships.
Why do replication requirements matter for cross-functional collaboration?
Replication across multiple slices from the same heart and across different donor hearts ensures data reliability and reproducibility, enabling confident interpretation by discovery, toxicology, and clinical teams.
What statistical analysis capabilities are required before implementation?
Implementation requires capability to analyze activation maps, conduction velocity vectors, action potential duration maps, and calcium decay constants, including statistical parameters like mean, median, and standard deviation for robust data interpretation.
