An In Silico Cardiomyocyte Reveals the Impact of Changes in CaMKII Signalling on Cardiomyocyte Contraction Kinetics...

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Biophysics

Background:

• Hypertrophic cardiomyopathy (HCM) is a genetic heart disease characterized by left ventricular hypertrophy, arrhythmias, and sudden cardiac death.
• It is typically caused by mutations in sarcomeric proteins and inherited in an autosomal-dominant pattern.

Purpose of the Study:

• To investigate the single-cell mechanisms underlying altered electrophysiology, contractility, energy metabolism, and crossbridge cycling in HCM using an in silico approach.
• To develop and validate a human ventricular cardiomyocyte model integrating these key cellular functions.

Main Methods:

• Developed a computational model of a human ventricular cardiomyocyte incorporating electrophysiology, metabolism, and force generation.
• Validated the model against experimentally observed HCM properties, including ion channel remodeling and altered myofilament calcium sensitivity.
• Utilized a spatial myofilament half-sarcomere model to analyze crossbridge states.

Main Results:

• Simulations indicated a 9% decrease in the phosphocreatine-to-ATP ratio, suggesting an energy supply-demand mismatch.
• The HCM model exhibited a higher fraction of crossbridges in force-producing states compared to the control.
• Impaired crossbridge kinetics were identified as a key feature of HCM.

Conclusions:

• The computational model reveals that impaired crossbridge kinetics in HCM are associated with an energy supply-demand imbalance.
• This energy mismatch may contribute to the pathophysiology of HCM.
• Targeting the ATP supply-demand ratio presents a potential therapeutic strategy to mitigate sudden death risk in HCM patients.