Characterization of the subcellular structure of engineered cardiomyocytes using small angle X-ray scattering

The structural and functional development of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is essential to understand in order to enable pharmaceutical testing, disease modeling, and ultimately therapeutic use. Recent developments in the field of bioengineering have led to improvements in the efficiency and efficacy of growth methods that allow hiPSC- CMs to be studied in greater detail. However, engineered cardiac tissue still has not achieved a level of maturation necessary for the majority of biomedical applications. Thus, new technologies and methods are necessary to realize the long-term benefits of engineered cardiac tissue. To better understand the development of the tissue, further characterization of the structure and function of these cardiomyocytes is required. In this work, we describe advances using a method not commonly applied to these materials, Small Angle X-ray Scattering (SAXS). SAXS was used to characterize the structural development of hiPSC- CMs on a 3D multicellular platform in their early stages of maturation. The myofilament lattice spacing was found to monotonically decrease as the tissue matured from its initial state post-seeding at a rate between 0.75 and 1 nm per day between days 3 and 10 of maturation. With 49 total samples across three different batches of tissue, the p value for correlation between the lattice plane spacing and maturation time was p