A contractile force measurement system for hiPSC-derived cardiac tissue integrated with an ultrathin, stretchable...

Mechanical stretch is a vital factor influencing the structural and functional properties of cardiac tissue, including its contractile force. While various platforms using elastic substrates have been developed to measure the contractile force under mechanical stretching in real time, significant challenges remain, such as achieving mechanical stability, maintaining sustained cell adhesion, and ensuring seamless system integration. In this study, we developed a contractile force measurement system for hiPSC-derived cardiac tissue using an ultrathin, stretchable polyurethane nanomesh substrate that addresses these limitations. The porous, fibrous structure of the nanomesh provides high mechanical compliance and stretchability, effectively serving as a biomimetic elastic substrate for cardiac tissue. Furthermore, the structure facilitates mechanical interlocking with the tissue, demonstrating significantly more sustained cell adhesion than does a flat substrate. Using this system, we successfully demonstrated stretch-dependent increases in contractile force, a phenomenon central to the Frank-Starling mechanism, and significant stretch-dependent differences in pharmacological responses. Our results suggest that this system could serve as a valuable platform for investigating cardiac function and pharmacological responses under mechanical stretch in vitro.