Rapid Regulation of Cardiomyocytes Adhesion on Substrates with Varied Modulus via Mechanical Cues.

In-depth understanding of the mechanisms underlying the adhesion of myocardial cells holds significant importance for the development of effective therapeutic biomaterials aimed at repairing damaged or pathological myocardial tissues. Herein, we present evidence that myocardial cells (H9C2) exhibit integrin-based mechanosensing during the initial stage of adhesion (within the first 2 h), enabling them to recognize and respond to variations in substrate stiffnesses. Moreover, the bioinformatics analysis of RNA transcriptome sequencing (RNA-seq) reveals that the gene expressions associated with initial stage focal adhesion (Ctgf, Cyr61, Amotl2, Prickle1, Serpine1, Akap12, Hbegf, and Nedd9) are up-regulated on substrates with elevated Young's modulus. The fluorescent immunostaining results also suggest that increased substrate stiffness enhances the expression of Y397-phosphorylated focal adhesion kinase (FAK Y397), talin, and vinculin and the assembly of F-actin in H9C2 cells, thereby facilitating the adhesion of myocardial cells on the substrate. Next, we utilize fluidic force microscopy (FluidFM)-based single-cell force spectroscopy (SCFS) to quantitatively evaluate the impact of substrate stiffness on the cell adhesion force and adhesion work, thus providing novel insights into the biomechanical regulation of initial cell adhesion. Our findings demonstrate that the maximum adhesion forces of myocardial cells exhibit a rise from 23.6 to 248.0 nN when exposed to substrates with different moduli. It is worth noting that once the αvβ3 integrins are blocked, the disparities in the adhesion forces of myocardial cells on these substrates become negligible. These results exhibit remarkable sensitivity of myocardial cells to mechanical cues of the substrate, highlighting the role of αvβ3 integrin as a biomechanical sensor for the regulation of cell adhesion. Overall, this work offers a prospective approach for the regulation of cell adhesion via integrin mechanosensing with potential practical applications in the areas of tissue engineering and regenerative medicine.