Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) have promise for elucidating basic biological processes, drug testing, and regenerative medicine, yet are known to be heterogenous and immature. Methods to analyze cardiomyocytes are typically destructive or require labeling that alters the cells’ performance. Thus, we have developed a non-invasive image-based method for analyzing and classifying cardiomyocytes based on their morphology and contractile properties, and applied this method to analyze the effects of controlling cell shape.
We optimized a diffraction phase microscope (DPM) to yield low noise optical thickness measurements at over 100 frames per second. We extracted contraction and relaxation motion cycles of single hiPSC-CMs and analyzed beat frequency and regularity. DPM also enabled comparisons of morphological characteristics by measuring the optical thickness of the cells.
We compared populations of hiPSC-CMs with controlled (patterned) and uncontrolled (unpatterned) shape and we observed the following: 1) patterning effectively controls the shape of the cells, while cells with the desired mature-like shape rarely appear in the unpatterned population, 2) patterned cells are more likely to beat with consistent and lower beat frequency compared to unpatterned cells, and 3) the patterns tend to select for larger (more mature-like) cells. Finally, we identified a cutoff point under which cells of a certain dry mass do not adhere to the patterns. These results indicate that controlling the shape of hiPSC-CMs improves their characteristics, which can be analyzed using DPM, and has the potential to yield more consistent research results and homogenous populations of cells for clinical applications.