Measuring and Modeling Self-Assembly in Cardiomyocytes

Myofibrillogenesis is the formation of myofibrils, the building blocks of muscle filaments. How neonatal rat ventricular myocytes and human induced-pluripotent stem cell (iPS) derived cardiomyocytes assemble will have a great impact on tissue engineering strategies for building myocardium in vitro. Normally, cardiomyocytes cultured on extracellular matrix islands form myofibrils that extend across the longest diagonal of the cells, but this is not necessarily the case for iPS-derived cardiomyocytes. In order to investigate why this is not always the case, it is advantageous to examine the self-assembly mechanism in vitro by quantifying the consistency of changes in cardiomyocyte architecture in response to a variety of input conditions. We developed the Co-orientational order parameter (COOP) to quantify the correlation between orientations of biological constructs and the consistency of cytoskeleton architecture. Using this newly invented parameter, we were able to investigate consistency across multiple length scales. To further explore this topic, microcontact printing was used to create cells of specific shapes (i.e. triangles, rectangles, squares, ovals, and circles) which were quantified for consistency through image analysis using the COOP. The images of these cells were used to determine at which length scales cardiomyocyte self-assembly was consistent and to fit and validate a computational myofibrillogenesis model developed previously in our lab. In the future, this model could be used to help uncover mechanisms of self-assembly of neonatal rat ventricular myocytes and human iPS-derived cardiomyocytes