Related Experiment Video
Updated: Sep 26, 2025
Author Spotlight: Real-Time Measurements of Calcium and Contractility Parameters in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes
Published on: May 26, 2023
Live-Cell Imaging of the Contractile Velocity and Transient Intracellular Ca2+ Fluctuations in Human Stem
Aviseka Acharya1, Harshal Nemade1, Krishna Rajendra Prasad1
1Working Group Sachinidis, Center for Physiology, Faculty of Medicine and University Hospital Cologne, The University of Cologne, 50931 Cologne, Germany.
Insights
Researchers developed novel human stem cell models for live imaging of heart cell function. This platform enables precise, real-time analysis of calcium transients and contraction, aiding cardiac disease research and drug screening.
Area of Science:
- Cardiology
- Stem Cell Biology
- Biotechnology
Background:
- Live-cell imaging is crucial for understanding heart disease mechanisms.
- Current methods for studying cardiomyocyte physiology in real-time have limitations.
Purpose of the Study:
- To engineer human stem cells for advanced live-cell imaging of cardiomyocyte function.
- To develop a platform for high-throughput drug screening and cardiac disease modeling.
Main Methods:
- Engineered human induced pluripotent stem cells with genetically-encoded calcium indicators (GECI) and α-cardiac actinin-copepod green fluorescent protein (ACTN2-copGFP).
- Utilized CRISPR-Cas9 and homology directed recombination for genetic modification.
- Differentiated engineered stem cells into cardiomyocytes for live imaging.
- Developed video analysis software to quantify calcium transients and sarcomere shortening velocity.
Main Results:
- Achieved real-time imaging of intracellular calcium ([Ca2+]i) transients and sarcomere shortening velocity in engineered cardiomyocytes.
- Demonstrated precise quantification of drug effects on cardiomyocyte contraction and relaxation (inotropic and lusitropic effects).
- Validated the platform's utility in assessing cardioactive drugs.
Conclusions:
- The developed human stem cell platform provides a powerful in vitro tool for cardiac research.
- Enables high-throughput drug screening and mechanistic studies of cardiac diseases using human-relevant models.
Abstract:
Live-cell imaging techniques are essential for acquiring vital physiological and pathophysiological knowledge to understand and treat heart disease. For live-cell imaging of transient alterations of [Ca2+]i in human cardiomyocytes, we engineered human-induced pluripotent stem cells carrying a genetically-encoded Ca2+-indicator (GECI). To monitor sarcomere shortening and relaxation in cardiomyocytes in real-time, we generated a α-cardiac actinin (ACTN2)-copepod (cop) green fluorescent protein (GFP+)-human-induced pluripotent stem cell line by using the CRISPR-Cas9 and a homology directed recombination approach. The engineered human-induced pluripotent stem cells were differentiated in transgenic GECI-enhanced GFP+-cardiomyocytes and ACTN2-copGFP+-cardiomyocytes, allowing real-time imaging of [Ca2+]i transients and live recordings of the sarcomere shortening velocity of ACTN2-copGFP+-cardiomyocytes. We developed a video analysis software tool to quantify various parameters of sarcoplasmic Ca2+ fluctuations recorded during contraction of cardiomyocytes and to calculate the contraction velocity of cardiomyocytes in the presence and absence of different drugs affecting cardiac function. Our cellular and software tool not only proved the positive and negative inotropic and lusitropic effects of the tested cardioactive drugs but also quantified the expected effects precisely. Our platform will offer a human-relevant in vitro alternative for high-throughput drug screenings, as well as a model to explore the underlying mechanisms of cardiac diseases.
