Cardiac myofibril networks induce shear stress

Area of Science:

• Cardiovascular Biology
• Biophysics
• Computational Biology

Background:

• Myofibril arrangement is crucial for cardiac muscle function, influencing force generation and contraction.
• Traditional models assumed uniaxial myofibril arrays, overlooking the complexity revealed by advanced imaging.

Purpose of the Study:

• To investigate how complex myofibril networks, rather than simple uniaxial arrays, modulate force and deformation in cardiomyocytes.
• To develop and utilize a computational model informed by real cellular morphology.

Main Methods:

• Morphological analysis of sheep left-ventricular cardiomyocytes.
• Deep learning segmentation of z-discs to analyze myofibril orientation.
• Non-linear finite element modeling of cardiomyocyte contraction using morphological data.

Main Results:

• Myofibrils exhibit orientation deviations up to 30° from the contraction axis.
• Simulations showed unique deformations, including internal rotation and off-axis movements, based on myofibril network geometry.
• Anisotropy in myofibril networks generates distinct shear stresses and spatial balancing of forces across the cell.

Conclusions:

• Myofibril networks significantly impact cardiac cell mechanics, generating complex deformations and stresses.
• The study highlights the importance of considering myofibril network complexity for understanding cardiac function and disease.
• Computational models integrating detailed myofibril morphology are essential for accurate cardiac mechanics simulation.