力信号对心肌细胞跳动的调控

Regulation of mechanical force on cardiomyocytes beating

心肌细胞的机械行为对生命健康起至关重要的作用,通常认为电信号和化学信号对心肌细胞的行为起调控作用.近年来发现细胞微环境的物理因素能够调控细胞的增殖、铺展、迁移和分化等行为,但其对心肌细胞机械行为的调控研究仍然缺乏.本文制备具有不同杨氏模量的水凝胶以模拟心肌细胞力学微环境,并通过加载力学刺激来探究细胞外基质中不同配体对心肌细胞的力学调控.研究表明机械力信号可以通过基质-配体-细胞的信号通路来调控心肌细胞的跳动,进而引起细胞间的耦合振荡实现心肌细胞的节律控制.这种力信号调控受细胞微环境的杨氏模量、细胞黏附配体种类和密度、以及力信号的强弱和节律三者共同影响,这为理解心率失调和心肌梗死后心力衰竭等疾病提供基础.

The mechanical behavior of cardiomyocytes plays an essential role in maintaining life and health.It is traditionally believed that both electrical signals and chemical signals modulate the cardiomyocytes behaviors.Recent discoveries have elucidated that the physical cues of microenvironment can regulate cell activities such as proliferation,spreading,migration,and differentiation.However,there is still limited research on regulating cardiomyocytes beating through mechanical force.Herein we prepare different polyacrylamide gels coated with different cell adhesion ligand proteins to simulate the physical microenvironment of cardiomyocytes.Then the mechanical loading forces are loaded by using a tungsten probe to stretch elastic hydrogels which can emulate the mechanical oscillations induced by the beating of adjacent cardiomyocytes.We investigate the responsive behavior of cardiomyocytes to external mechanical oscillations within various physical microenvironments.Firstly,we load 1 Hz mechanical oscillation on the matrix(E=11 kPa)with different kinds and concentrations of ligands(0,5,20,100μg/mL)to stimulate cardiomyocytes and observe their mechanical response behavior.Our findings indicate that all kinds of ligands including Laminin,Fibronectin and Collagen I,can mediate the cardiomyocytes response to extrinsic mechanical oscillatory stimuli,which might be due to distinct mechanisms of mechanical force coupling(Fig.(b)).This suggests that mechanical force signals can regulate the beating of cardiomyocytes through matrix-ligand-cell signaling pathway,thereby inducing intercellular coupled oscillations for rhythmic control of cardiomyocytes.Cardiomyocytes cultured on the matrix coated with 20μg/mL Laminin show the highest and most stable response fraction.We hypothesize that there exist dual force transduction pathways for Laminin binding to integrin and dystrophin glycoprotein complex(DGCFig.(a)).We further analyze the cardiomyocytes behaviors under mechanical oscillation with different values of substrate stiffness(E=1.8,11,27 kPa)and concentrations of Laminin(0,5,20,100μg/mL).We find that cardiomyocytes cultured on 1.8 kPa coated with 20μg/mL Laminin show the highest response fraction(Fig.(c)).Our results demonstrate that the stiffness of substrate,the type and density of cell adhesion ligands,as well as the strength and rhythm of the mechanical signals can synergetically affect the cardiomyocytes responses to external mechanical stimulations,which provides the foundation for understanding the diseases such as cardiac arrhythmias and heart failure following myocardial infarction.