Polystyrene microplastics size as a key localization determinant for isolated adult cardiomyocytes

There is growing evidence of the cytotoxic effects of micro- and nanoplastics (MPs) on the cardiovascular system. However, the proof of their direct interaction with living cardiomyocytes is limited. This study aimed to analyze the interaction of polystyrene (PS) MPs with freshly isolated adult cardiomyocytes. The primary cardiomyocytes from adult rat hearts were exposed to solutions with MPs of different sizes (20, 100, 200, 500, 1000, and 2000 nm, respectively) for up to six hours. We observed that small MPs, sized 20 nm, showed mostly intracellular localization, and MPs sized 100 nm had partial intracellular location. On the other hand, MPs sized 200-1000 nm had predominantly surface localization. The larger MPs, sized 2000 nm, did not interact with the cardiomyocytes. These findings reveal the complexity of MPs-induced interaction with cardiac cells and suggest the size of the MPs as one of the key localization determinants for these cells.