In vitro validation during PFA device development
Pulsed field ablation (PFA) is an emerging energy modality for treating arrhythmias. Its potential for selective myocardial ablation through predominantly nonthermal injury has made it an important area of cardiovascular intervention research.
Before animal studies, understanding how different pulse parameters affect cardiomyocytes is essential to defining a safety window and optimizing energy delivery. Our tiered in vitro PFA platform spans primary rat cardiomyocytes and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs).
Tiered cell models for development and NMPA-oriented studies
Animal-derived and human-derived model tiers are selected according to development stage and regulatory objectives, supporting early parameter optimization and studies intended to contribute to registration submissions.
- Animal-derived cardiomyocyte models: These support early energy-parameter screening, waveform optimization and safety-window evaluation. Analysis of electroporation and calcium responses establishes quantitative relationships between electric-field strength and cell injury, providing baseline evidence for subsequent human-cell studies.
- Human multicell-type assessment: To address cellular selectivity questions in the context of China's National Medical Products Administration (NMPA), human cardiomyocytes are assessed alongside smooth muscle cells, endothelial cells and neurons. This comparative framework evaluates tissue selectivity and safety boundaries across energy settings.
Applying these model tiers sequentially links basic parameter optimization with preclinical validation and supports the development of scientifically interpretable data aligned with the project's regulatory objectives. Model relevance and the applicable evidence requirements must be evaluated for each project; a cell-based study alone does not establish regulatory acceptance.
Experimental design and pulse parameters
Electric-field parameter matrices can be designed for each model, including:
- Electric-field strength
- Pulse width
- Number of pulses
- Pulse frequency
Microscopy and electrophysiological assessment are used to quantify reversible electroporation thresholds (EFT) and irreversible electroporation (IRE) thresholds for different energy combinations. Temperature measurements alongside the electrical studies help distinguish nonthermal from thermal effects.
Key experimental measurements
- Cell membrane integrity: Real-time fluorescence microscopy using indicator dyes.
- Calcium transient dynamics: Fluorescent probes track changes in intracellular Ca²⁺ signals.
- Action potential-related changes: Voltage-sensitive probes characterize optical voltage responses within the excitation-contraction coupling framework. These fluorescence signals are not direct measurements of absolute membrane potential.
- Temperature rise: Real-time measurement of local temperature changes.
- Electric-field simulation: Finite element modeling (FEM) reproduces electric-field strength distributions and supports analysis of the spatial distribution of injury in the cell layer.
Statistical analysis and inverse electric-field analysis support standardized reporting of EFT/IRE thresholds, thermal effects, cell-death distributions and electric-field maps for device optimization and safety assessment.
Applications across development stages
The in vitro PFA platform can be adapted to objectives at different stages of device development:
- Early energy-parameter screening and waveform optimization, for which neonatal rat cardiomyocyte (NRCM) models are recommended.
- Catheter geometry and electrode-layout optimization using adult rat ventricular myocyte (ARVM) models with electric-field simulation.
- Validation in human-cell models and mechanistic studies using hiPSC-CMs.
- Thermal safety-window assessment and studies of electric-field interactions with tissue.
Services span experimental design, electric-field simulation, data analysis and reporting, tailored to device geometry, output characteristics and the intended tissue type. Animal-derived cardiomyocytes or human hiPSC-CMs are selected according to the research objective and development stage.
