Modeling alcohol-induced neurotoxicity using human induced pluripotent stem cell-derived three-dimensional cerebral organoids

Abstract

Maternal alcohol exposure during pregnancy can substantially impact the development of the fetus, causing a range of symptoms, known as fetal alcohol spectrum disorders (FASDs), such as cognitive dysfunction and psychiatric disorders, with the pathophysiology and mechanisms largely unknown. Recently developed human cerebral organoids from induced pluripotent stem cells are similar to fetal brains in the aspects of development and structure. These models allow more relevant in vitro systems to be developed for studying FASDs than animal models. Modeling binge drinking using human cerebral organoids, we sought to quantify the downstream toxic effects of alcohol (ethanol) on neural pathology phenotypes and signaling pathways within the organoids. The results revealed that alcohol exposure resulted in unhealthy organoids at cellular, subcellular, bioenergetic metabolism, and gene expression levels. Alcohol induced apoptosis on organoids. The apoptotic effects of alcohol on the organoids depended on the alcohol concentration and varied between cell types. Specifically, neurons were more vulnerable to alcohol-induced apoptosis than astrocytes. The alcohol-treated organoids exhibit ultrastructural changes such as disruption of mitochondria cristae, decreased intensity of mitochondrial matrix, and disorganized cytoskeleton. Alcohol exposure also resulted in mitochondrial dysfunction and metabolic stress in the organoids as evidenced by (1) decreased mitochondrial oxygen consumption rates being linked to basal respiration, ATP production, proton leak, maximal respiration and spare respiratory capacity, and (2) increase of non-mitochondrial respiration in alcohol-treated organoids compared with control groups. Furthermore, we found that alcohol treatment affected the expression of 199 genes out of 17,195 genes analyzed. Bioinformatic analyses showed the association of these dysregulated genes with 37 pathways related to clinically relevant pathologies such as psychiatric disorders, behavior, nervous system development and function, organismal injury and abnormalities, and cellular development. Notably, 187 of these genes are critically involved in neurodevelopment, and/or implicated in nervous system physiology and neurodegeneration. Furthermore, the identified genes are key regulators of multiple pathways linked in networks. This study extends for the first time animal models of binge drinking-related FASDs to a human model, allowing in-depth analyses of neurotoxicity at tissue, cellular, subcellular, metabolism, and gene levels. Hereby, we provide novel insights into alcohol-induced pathologic phenotypes, cell type-specific vulnerability, and affected signaling pathways and molecular networks, that can contribute to a better understanding of the developmental neurotoxic effects of binge drinking during pregnancy.

The Effects of Environmental Adversities on Human Neocortical Neurogenesis Modeled in Brain Organoids

“…Another study focused on acute ethanol exposure for 6 h of 2 month old cerebral organoids, where apoptosis was induced at ethanol concentrations of 115 mg/dl. This concentration is comparable to the blood ethanol concentration upon binge drinking (80 mg/dl, corresponding roughly to four glasses of wine over less than 2 h) ( Arzua et al, 2020 ). In addition to apoptosis induction, the authors noticed ultrastructural changes, such as abnormal mitochondria cristae and glycogen foci ( Arzua et al, 2020 ).…”

“…This concentration is comparable to the blood ethanol concentration upon binge drinking (80 mg/dl, corresponding roughly to four glasses of wine over less than 2 h) ( Arzua et al, 2020 ). In addition to apoptosis induction, the authors noticed ultrastructural changes, such as abnormal mitochondria cristae and glycogen foci ( Arzua et al, 2020 ). The abnormal morphology of mitochondria was accompanied by functional changes in energy metabolism ( Arzua et al, 2020 ).…”

“…In addition to apoptosis induction, the authors noticed ultrastructural changes, such as abnormal mitochondria cristae and glycogen foci ( Arzua et al, 2020 ). The abnormal morphology of mitochondria was accompanied by functional changes in energy metabolism ( Arzua et al, 2020 ). More changes were found at the transcriptional level with microarray analysis showing a deregulation of groups of genes involved in cell proliferation, nervous system development, and neurological diseases ( Arzua et al, 2020 ).…”

“…The abnormal morphology of mitochondria was accompanied by functional changes in energy metabolism ( Arzua et al, 2020 ). More changes were found at the transcriptional level with microarray analysis showing a deregulation of groups of genes involved in cell proliferation, nervous system development, and neurological diseases ( Arzua et al, 2020 ). Given the complexity of cell type composition in cerebral organoids at 2 months of differentiation ( Lancaster et al, 2013 ), these results provide an interesting starting point for further experiments on cell type-specific events.…”

Making Sense of Patient-Derived iPSCs, Transdifferentiated Neurons, Olfactory Neuronal Cells, and Cerebral Organoids as Models for Psychiatric Disorders

“…As a model for fetal alcohol spectrum disorder, the neurotoxic effects of ethanol exposure on metabolic, tissue, and cellular levels were shown using 2-month old iPSC-derived human cerebral organoids ( Arzua et al, 2020 ).…”