Lung organoids and microplastic fibers: a new exposure model for emerging contaminants

Abstract

Background: Three–dimensional (3D) structured organoids are the most advanced in vitro models for studying human health effects, but they have not yet been applied to evaluate the biological effects associated with microplastic exposure. Fibers from synthetic clothes and fabrics are a major source of airborne microplastics, and their release from dryer machines is still poorly understood. Objectives: In this study, we aimed to establish an in vitro organoid model of human lung epithelial cells to evaluate its suitability for studying the effects of airborne microplastic contamination on humans. Furthermore, we aimed to characterize the microplastic fibers (MPFs) released in the exhaust filter of a household dryer and to test their interactions and inflammatory effects on the established lung organoids. Methods: The polyester fibers emitted from the drying of synthetic fabrics were collected. Morphological characterization of the fibers released into the air filter was performed by optical microscopy and scanning electron microscopy (SEM)/energy dispersive x–ray spectroscopy (EDS). The organoids were exposed to various MPF concentrations (1, 10, and 50 mg L−1) and analyzed by optical microscopy, SEM, and confocal microscopy. Gene expression analysis of lung–specific genes, inflammatory cytokines, and oxidative stress–related genes was achieved by quantitative reverse transcription–polymerase chain reaction (qRT–PCR). Results: We successfully cultured organoids with lung–specific genes. The presence of MPFs did not inhibit organoid growth, but polarized cell growth was observed along the fibers. Moreover, the MPFs did not cause inflammation or oxidative stress. Interestingly, the MPFs were coated with a cellular layer, resulting in the inclusion of fibers in the organoid. Discussion: This work could have potential long–term implications regarding lung epithelial cells undergoing repair. This preliminary exposure study using human lung organoids could form the basis for further research regarding the toxicological assessment of emerging contaminants such as micro– or nanoplastics.

Are We Underestimating Anthropogenic Microfiber Pollution? A Critical Review of Occurrence, Methods, and Reporting

“…Cox et al (2019) recently estimated that annual inhalation of microplastic particles (including synthetic microfibers) ranges from 48,000 to 62,000 particles, concluding that inhalation was the greatest human health exposure pathway. While studies investigating the effects of microfiber inhalation are limited, in vivo studies conducted in industrial settings and in vitro research on human lung organoids have suggested acute and chronic health impacts following exposure to synthetic and nonsynthetic microfibers (Eschenbacher et al, 1999;Hours et al, 2007;Winkler et al, 2021). Given their abundance in indoor air and dust, future studies estimating human exposure to microfibers should incorporate natural and semisynthetic microfibers to better understand the threat that the full suite of anthropogenic microfibers poses to human health.…”

Human Embryos, Induced Pluripotent Stem Cells, and Organoids: Models to Assess the Effects of Environmental Plastic Pollution

“…The organoids were exposed to various MPF concentrations (1, 10, and 50 mg L -1 ) and analyzed by optical microscopy, scanning electron microscopy (SEM), and confocal microscopy. Gene expression assessment of lung-specific genes, inflammatory cytokines, and oxidative stress-related genes was performed by qRT-PCR and showed no significant differences when compared to the control group (Winkler et al, 2021; the contribution is a preprint). Even though MPFs did not have an adverse effect on lung organoids, there was the polarization of the cell growth along the fibers, similarly to organoid-covered plastic fibers with a cellular layer in the study of van Dijk et al (2021; the contribution is a preprint).…”

“…The Notch1 and Notch2 signaling pathways were downregulated, as well as their ligands Jag1 and Jag2, which are responsible for the development of airway epithelial cells, and club cells (van Dijk et al, 2021; the contribution is a preprint). Winkler and coworkers used human lung organoids to examine the effect of microplastic fibers (MPFs) on organoid growth and their inflammatory effects on the established lung organoids (Winkler et al, 2021; the contribution is a preprint). Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used for gene expression analysis of oxidative stress-related genes, lungspecific genes, and inflammatory cytokines (Winkler et al, 2021; the contribution is a preprint).…”

“…Winkler and coworkers used human lung organoids to examine the effect of microplastic fibers (MPFs) on organoid growth and their inflammatory effects on the established lung organoids (Winkler et al, 2021; the contribution is a preprint). Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used for gene expression analysis of oxidative stress-related genes, lungspecific genes, and inflammatory cytokines (Winkler et al, 2021; the contribution is a preprint). No significant differences in the gene expression of cytokines or oxidative stress-related genes such as superoxide dismutase family genes (SOD1 and SOD2), glutathione detox-related genes [glutathione detox-related genes (GSTA1 and GPX1)], catalase (CAT), and ROS-controlling genes [(NADPH oxidase-2 (NOX2), cyclo-oxygenase 1 (COX1), NADH dehydrogenase 1 (ND1)] were noticed in human lung organoids after exposure to MPFs (Winkler et al, 2021; the contribution is a preprint).…”

“…No significant differences in the gene expression of cytokines or oxidative stress-related genes such as superoxide dismutase family genes (SOD1 and SOD2), glutathione detox-related genes [glutathione detox-related genes (GSTA1 and GPX1)], catalase (CAT), and ROS-controlling genes [(NADPH oxidase-2 (NOX2), cyclo-oxygenase 1 (COX1), NADH dehydrogenase 1 (ND1)] were noticed in human lung organoids after exposure to MPFs (Winkler et al, 2021; the contribution is a preprint). The authors also confirmed no significant difference in gene expression responsible for epithelial lung markers such as NK2 homeobox 1 (NKX2.1) and Claudin 1 (CLDN1) as well as the specific airway lung markers surfactant protein A1 (SFTPA1) and surfactant protein C (SFTPC) in alveolar-type 2 progenitor cells (AT2 cells), secretoglobin family 1A member 1 (SCGB1A1) (club cells), nephrocystin 1 (NPHP1), dynein axonemal heavy chain 5 (DNAH5) (ciliated cells), and keratin 5 (KRT5) (basal cells) in human lung organoids exposed to MPFs and the control group (Winkler et al, 2021; the contribution is a preprint). Schwartz et al (2015) studied developmental neurotoxicity by using reproducible 3D neural constructs containing vascular and microglial components on synthetic FIGURE 1 | Human 3D organoid systems: a promising platform to study the effect of environmental pollution.…”