Sarcomere dynamic instability and stochastic heterogeneity drive robust cardiomyocyte contraction.

Stochastic heterogeneity and dynamic instability in sarcomeres enable robust cardiomyocyte contraction despite mechanical constraints, with 85 kPa stiffness revealing significant heterogeneity.

• Why it matters: Understanding sarcomere behavior is crucial because their intrinsic stochastic dynamics may underpin how heart cells adapt to mechanical stress, impacting cardiac health and disease.
• What they did: Using fluorescent sarcomere reporters on micropatterned soft gels of varying stiffness combined with AI tracking, the study analyzed sarcomere dynamics in human induced pluripotent stem cell-derived cardiomyocytes, focusing on heterogeneity and stochastic fluctuations.
• The result: Findings show that sarcomeres exhibit non-uniform, stochastic oscillations and overextensions, which help prevent damage and facilitate adaptation, suggesting a shift from protective fluctuations to deterministic overload in cardiomyopathy.