Evaluation of phthalates induced cardiotoxicity using human iPSCs-derived cardiomyocyte and dual-cardiotoxicity evaluation methods

Phthalates, known as plasticizers, are endocrine disruptor, and their risks are being highlighted as their use increases worldwide. Di-2-ethylhexyl phthalate (DEHP), the most prevalent of the phthalates, is known to be toxic to humans, and it has recently been reported to be linked to cardiotoxicity. Although many other phthalates are also widely used, data on their cardiotoxic effects are yet to be well established. In this study, we assessed the cardiotoxic potential of various phthalates using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and a microelectrode array-based dual-cardiotoxicity evaluation method previously reported. Cytotoxicity results showed that acute exposure to DEHP, dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), and di-n-octyl phthalate (DnOP) did not affect the viability of hiPSC-CMs. Before examining the functional changes in hiPSC-CMs caused by exposure to these four phthalates, we present changes in field potential (FP) and contractility based on the blocking of major ions for reference. Contrary to concerns, FP results showed a dramatic decrease in spike amplitude, beat period, and FP duration (FPD) at high doses of DBP and BBP rather than DEHP. Interestingly, DnOP resulted in a prolonged FPD, unlike the others. Furthermore, contractility results indicated that, unlike DEHP and DnOP, high doses of DBP and BBP caused beating arrest along with decreased beat amplitude. Overall, this study demonstrated that phthalates other than DEHP can also induce cardiotoxicity, even with acute exposure. It is expected that the application of the established evaluation method will facilitate the development of safe alternatives.