Phenotypic Assays for Characterizing Compound Effects on Induced Pluripotent Stem Cell-Derived Cardiac Spheroids.

Area of Science:

• Cardiovascular research
• Drug discovery and development
• Stem cell biology

Background:

• Developing predictive cell-based assays for compound screening is crucial in drug discovery.
• Traditional 2D cell cultures often lack the complexity and predictive power needed for accurate toxicity assessments.
• Human induced pluripotent stem cell-derived cardiomyocytes offer a promising model for studying cardiac function and toxicity.

Purpose of the Study:

• To establish high-throughput compatible 3D cardiac spheroid assays for cardiotoxicity assessment.
• To characterize compound effects on cardiomyocyte beating rates, patterns, and morphology using advanced imaging techniques.
• To compare the efficacy of 3D versus 2D models in evaluating drug-induced cardiotoxicity.

Main Methods:

• Utilized human induced pluripotent stem cell-derived cardiomyocytes to form 3D cardiac spheroids.
• Employed high-content imaging and fast kinetic fluorescence imaging to monitor intracellular Ca2+ levels and beating patterns.
• Applied advanced image analysis for multiparametric characterization of Ca2+ oscillations and spheroid morphology.

Main Results:

• Phenotypic assays successfully characterized beating frequency, amplitude, Ca2+ oscillation patterns, and cell viability in 3D spheroids.
• A set of 22 compounds, including known cardiotoxic drugs, were assayed, revealing distinct concentration responses and time dependencies in 3D models compared to 2D.
• Significant concordance in observed phenotypes was noted, but essential differences highlighted the distinct biological nature of 3D cardiac spheroids.

Conclusions:

• 3D cardiac spheroids represent a functionally distinct and more biologically relevant model system than traditional 2D cultures.
• Phenotypic assays using 3D model systems are suitable for high-throughput screening and in vitro cardiotoxicity assessment.
• This approach enhances the predictive power of drug discovery by providing a more complex and relevant cellular environment.