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Researchers investigated how geometric confinement and substrate stiffness affect force generation in human induced pluripotent stem cell-derived cardiomyocytes. Using traction force microscopy and live-cell imaging, they found that geometric confinement leads to longer resting sarcomeres and more pronounced shortening on both physiological (10 kPa) and fibrotic (30 kPa) stiffness substrates. The combination of geometric confinement and physiological stiffness resulted in characteristics associated with mature cardiomyocytes, including higher peak contractile stress and faster relaxation, while substrate stiffness alone primarily influenced peak contractile stress rather than sarcomere length.
Why it matters
These findings have important implications for cardiac disease modeling, drug testing, and regenerative medicine applications using stem cell-derived cardiomyocytes. The results demonstrate that both cell geometry and substrate stiffness must be carefully controlled when using these cells as model systems, as they interact to determine cardiomyocyte maturation and function, which is particularly relevant for understanding heart failure and fibrosis.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Cardiomyocyte contraction is essential for the pumping action of the heart and deteriorates after myocardial damage, either as a consequence of irreversible cardiomyocyte injury or stiffening of the extracellular matrix, a process described as fibrosis. Cell geometry and substrate stiffness not only influence sarcomere architecture and contractility, they also determine how much work the cardiomyocytes can transfer to their environment. Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes provide a model system to examine these effects in a controlled manner, enabling us to mimic key features of the cardiac environment in vitro. Here we show that geometric confinement and substrate stiffness influence different aspects of cardiomyocyte force generation. By combining traction force microscopy and live-cell imaging of hiPSC-derived cardiomyocytes on soft and patterned substrates, we find that geometric confinement leads to longer resting sarcomeres and more pronounced sarcomere shortening on substrates with both physiological (10 kPa) and fibrotic (30 kPa) stiffness. Interestingly, the substrate stiffness itself has little effect on resting sarcomere length, but influences the peak contractile stress. On 10 kPa substrates, confined cells generate higher peak contractile stresses than unconfined cells, whereas this difference is not observed at 30 kPa. Confinement also results in faster mechanical relaxation at 10 kPa, with no detectable difference at 30 kPa. The combination of defined cell geometry and physiological stiffness leads to longer resting sarcomere lengths, more pronounced sarcomere shortening, higher peak contractile stress, and faster relaxation, features associated with a more mature cardiomyocyte phenotype. These findings show that the mechanical consequences of cell geometry depend on substrate stiffness and, therefore, both aspects have to be considered when employing hiPSC-derived cardiomyocytes as a model system in mechanobiology research, disease modeling and drug testing.
Source: Force generation of cardiomyocytes in engineered environments