Probing the mechanobiological properties of human embryonic stem cells in cardiac differentiation by optical tweezers.

Human embryonic stem cells (hESC) and hESC-derived cardiomyocytes (hESC-CM) hold great promise for the treatment of cardiovascular diseases. However the mechanobiological properties of hESC and hESC-CM remains elusive. In this paper, we examined the dynamic and static micromechanical properties of hESC and hESC-CM, by manipulating via optical tweezers at the single-cell level. Theoretical approaches were developed to model the dynamic and static mechanical responses of cells during optical stretching. Our experiments showed that the mechanical stiffness of differentiated hESC-CM increased after cardiac differentiation. Such stiffening could associate with increasingly organized myofibrillar assembly that underlines the functional characteristics of hESC-CM. In summary, our findings lay the ground work for using hESC-CMs as models to study mechanical and contractile defects in heart diseases.