Multi-Imaging Method to Assay the Contractile Mechanical Output of Micropatterned Human iPSC-Derived Cardiac Myocytes
Rationale: During each beat, cardiac myocytes generate the mechanical output necessary for heart function through contractile mechanisms that involve shortening of sarcomeres along myofibrils. Human induced pluripotent stem cells can be differentiated into cardiac myocytes that model cardiac contractile mechanical output more robustly when micropatterned into physiological shapes. Quantifying the mechanical output of these cells enables us to assay cardiac activity in a dish.
Objective: We sought to develop a computational platform that integrates analytical approaches to quantify the mechanical output of single micropatterned cardiac myocytes from microscopy videos.
Methods and Results: We micropatterned single cardiac myocytes differentiated from human induced pluripotent stem cells on deformable polyacrylamide substrates containing fluorescent microbeads. We acquired videos of single beating cells, of microbead displacement during contractions, and of fluorescently labeled myofibrils. These videos were independently analyzed to obtain parameters that capture the mechanical output of the imaged single cells. We also developed novel methods to quantify sarcomere length from videos of moving myofibrils and to analyze loss of synchronicity of beating in cells with contractile defects. We tested this computational platform by detecting variations in mechanical output induced by drugs and in cells expressing low levels of myosin binding protein C.
Conclusions: Our method can measure cardiac function in cardiac myocytes differentiated from induced pluripotent stem cells and determine contractile parameters that can be used to elucidate the mechanisms that underlie variations in cardiac myocyte function. This platform will be amenable to future studies of the effects of mutations and drugs on cardiac function.
- Received November 23, 2016.
- Revision received April 7, 2017.
- Accepted April 11, 2017.