Acute, uniaxial, static stretch of 6% induced dynamic sarcomeric addition in 50% of live neonatal cardiomyocytes under longitudinal stretch compared to 0% in unstretched controls.
The study provides the first live-cell observations of dynamic sarcomeric addition in neonatal cardiomyocytes under static stretch, offering insights into the mechanisms of cardiac hypertrophy.
Absolute Event Rate: 50% vs 0%
p-value: p=0.0070
An increase in mechanical load in the heart causes cardiac hypertrophy, either physiologically (heart development, exercise and pregnancy) or pathologically (high blood pressure and heart-valve regurgitation). Understanding cardiac hypertrophy is critical to comprehending the mechanisms of heart development and treatment of heart disease. However, the major molecular event that occurs during physiological or pathological hypertrophy is the dynamic process of sarcomeric addition, and it has not been observed. In this study, a custom-built second harmonic generation (SHG) confocal microscope was used to study dynamic sarcomeric addition in single neonatal CMs in a 3D culture system under acute, uniaxial, static, sustained stretch. Here we report, for the first time, live-cell observations of various modes of dynamic sarcomeric addition (and how these real-time images compare to static images from hypertrophic hearts reported in the literature): 1) Insertion in the mid-region or addition at the end of a myofibril; 2) Sequential addition with an existing myofibril as a template; and 3) Longitudinal splitting of an existing myofibril. The 3D cell culture system developed on a deformable substrate affixed to a stretcher and the SHG live-cell imaging technique are unique tools for real-time analysis of cultured models of hypertrophy.
Yang et al. (Wed,) conducted a other in In vitro simulated cardiac hypertrophy (n=39). Acute, uniaxial, static, sustained stretch vs. Unstretched cells was evaluated on Observation of sarcomeric addition under longitudinal stretch (95% CI 0.147-0.686, p=0.0070). Acute, uniaxial, static stretch of 6% induced dynamic sarcomeric addition in 50% of live neonatal cardiomyocytes under longitudinal stretch compared to 0% in unstretched controls.