Potential Threats of Nanoplastic Accumulation in Human Induced Pluripotent Stem Cells

Abstract Background: Micro- and nanoplastics (NPs) produced from the bulk fragmentation are rampant in the world by enormous plastic trash everyday life. NPs can be exposed to humans through a variety of routes, including inhalation and intake. The threat to humans from NPs is increasing invisibly. Nowadays, many people are concerned about human safety and health, but few are reported about the effects of NP on humans. To overcome the limitations in human studies, human induced pluripotent stem cells (hiPSCs) were used as an optimal in vitro platform to investigate developmental toxicology and subtle changes on cellular functions in terms of differentiation potential throughout a long-term culture. Results: Negatively charged polystyrene nanoplastics (PS NPs) were used to exclude acute toxic issues of surface charge and investigate the impact of the NP's size and nature during bioaccumulation. Intracellular observations revealed that NPs up to 1000 nm were over-internalized into single cells within 48 h, and smaller NPs demonstrated greater potency at decreasing number of viable cells by a strong correlation with the number of NPs on an equal mass basis. Also, PS NPs caused a significant reduction in self-renewal capacity of hiPSCs for 48 h. After the cells were exposed to PS NPs for 48 to 96 h at the beginning of the differentiation process, NPs accumulated in hiPSC did not render cellular functions vulnerable or adversely affect EB formation, EB-mediated differentiation, and neural lineage differentiation for up to 14 days. Conclusion : This study confirmed that hiPSC exposure to polystyrene nanoplastics results in acute toxicity and non-significant long-term effects on cellular functions. This report is important for understanding the developmental toxicology of nanoplastics and the origin of disease.