Toxicity Evaluation of Glyphosate and Its Formulation Adjuvant, Polyoxyethylene Tallow Amine (POEA) on Cardiogenesis Using a Novel Human Heart Organoid Model

Based on morphological observations of animal models, people had reported that Glyphosate (Gly) herbicide exposure would cause cardiac abnormalities. However, multiple studies focused on developing toxicity of Gly-based herbicides (GBHs), which included not only Gly but also its adjuvant, causing molecule mechanisms hard to be clarified. To evaluate both the individual and combined exposure effects of Gly and its adjuvant, Polyoxyethylene tallow amine (POEA), on human heart development, we constructed a human pluripotent stem cells-derived model named human heart organoids (hHOs), which could imitate bona fide human cardiogenesis process. We conducted an exposure of Gly and POEA throughout the differentiation process, alone or in combination with hHOS, to hHOs from day 0 to day 16. Morphological, immunofluorescencet, and transcriptomic analyses showed that individual Gly exposure would result in epicardium hyperplasia, while single POEA exposure would induce cell apoptosis and restricted cardiomyocyte contraction. The combined exposure outcomes resembled POEA, where malformation mainly occurred in cardiomyocyte subtypes specification, atrioventricular septation formation, and heart contraction protein synthesis. To conclude, by employing a novel model, we demonstrated the adverse effects of Gly and proved the adjuvant POEA possessed stronger toxicity; we also depicted the similarities and differences between single and combined exposure. Moreover, we brought a new model method for human exposure toxicity evaluation. Overall design: To further study the Gly and POEA's influence on hHOs and clarify the underlying mechanism, we conducted transcriptome analysis on hHOs from high-dose groups containing 10µg/mL Gly, 3.33µg/mL POEA and combined exposure of 10µg/mL Gly with 3.33µg/mL POEA at day 16 of the differentiation, when the hHOs possessed distinct phenotype.