Assessment of Induced Pluripotent Stem Cell-Derived Cardiomyocyte Contractility Using Micropost Arrays

Cardiovascular stem cell therapies have shown increasing promise as a potential therapeutic means for reversing the effects of a myocardial infarction [1]. Out of the currently available sources of human stem cells, human induced pluripotent stem cells (hiPSCs) are very promising in that: the number of cell lines that can be induced to the pluripotent state is extremely vast, they serve as a potential source for patient-specific cardiomyocytes, and their use is non-controversial. However, before they can be used feasibly in a clinical setting, the functional engraftment of these cells into the host tissue must be improved [2]. It is hypothesized that the structural and functional maturity of the stem-cell derived cardiomyocytes prior to implantation, may significantly affect the ability of these cells to engraft with resident heart tissue [3]. One of the most important functional characteristics of a cardiomyocyte is its ability to produce contractile forces. However, assessing the contractile properties of single iPS-CMs is a difficult task. iPS-CMs generally have relatively unorganized cytoskeletons, with stress fibers in multiple directions. This trait renders one or two-point force assays ineffectual in determining total cell forces. Furthermore, iPS-CMs don’t spread well on tissue culture surfaces, which make two-dimensional force measurements almost impossible.