On-chip single-cell-shape control technology for understanding contractile motion of cardiomyocytes measured using optical image analysis system

Quantitative evaluation of mechanophysiological responses of cardiomyocytes has become more important for more precise prediction of cardiotoxicity. For the accurate detection of cardiomyocyte contraction, we have developed an on-chip single-cell-shape control technology on the basis of an agarose microchamber system and an on-chip optical image analysis system that records the contractile motions of cardiomyocytes with noninvasive/nondestructive measurement for long-term experiments. Using this on-chip single-cell-shape control technology, the shape of single cardiomyocytes was controlled by seeding the cells in 21-m-radius (circular) or 20 × 70μm2 (rectangular) agarose microchambers. To detect the contractility of cardiomyocytes, the cells were labeled with microbeads attached onto the surface of target cells and the motion of beads was acquired and analyzed using a newly developed wider-depth-of-field optics equipped with a 1/100 s high-speed digital camera. Mechanophysiological properties such as displacement and direction of movement were obtained using a real-time processing system module at spatial and temporal resolutions of 0.15 μm and 10 ms, respectively. Comparisons of displacement and direction of contraction between circular and rectangular cardiomyocytes indicated that the rectangular cardiomyocytes tended to contract along the longitudinal direction as in a real heart. This result suggests that the shape of cells affected the function of cells. The on-chip single-cell-shape control technology and optical image analysis system enable the detection of the motion of contraction of single-shape-controlled cardiomyocytes, and are expected to be applicable to the more precise prediction of cardiotoxicity.