Establishment of a rapid drug screening system based on embryonic stem cells

Mitochondrial dynamics when mitochondrial toxic chemicals exposed in 3D cultured mouse embryonic stem cell

Mitochondria need to use considerable energy for the intracellular organelles that produce ATP. They are abundant in the cells of organs, such as muscles, liver, and kidneys. The heart, which requires a lot of energy, is also rich in mitochondria. Mitochondrial damage can induce cell death. Doxorubicin, acetaminophen, valproic acid, amiodarone, and hydroxytamoxifen are representative substances that induce mitochondrial damage. On the other hand, the effects of this substance on the progress of cardiomyocyte-differentiating stem cells have not been investigated. Therefore, a 3D cultured embryonic body toxicity test was performed. The results confirmed that the cytotoxic effects on cardiomyocytes were due to mitochondrial damage in the stage of cardiomyocyte differentiation. After drug treatment, the cells were raised in the embryoid body state for four days to obtain the ID50 values, and the levels of mRNA expression associated with the mitochondrial complex were examined. The mitochondrial DNA copy numbers were also compared to prove that the substance affects the number of mitochondria in EB-state cardiomyocytes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-022-00161-1.

Cytotoxicity evaluation and mechanism of endocrine-disrupting chemicals by the embryoid body test

Endocrine-disrupting chemicals (EDCs) are a structurally diverse class of synthetic and natural compounds. EDCs can cause non-communicable diseases such as obesity, type 2 diabetes, thyroid disorders, neurodevelopmental disease, hormone-dependent cancers, and reproductive disorders. The embryoid body test (EBT) is a developmental toxicity test method that determines the size of embryoid bodies (EBs) and the viability of mouse embryonic stem cells (mESCs) and fibroblasts (3T3 cells). The present study used the EBT to perform cytotoxicity evaluations of 10 EDCs and assessed the mechanistic relationship between endoplasmic reticulum (ER) stress and cytotoxicity. According to the statistical analysis and prediction model results, methylparaben, butylparaben, propylparaben, ethylparaben, triclosan, octylphenol, methoxychlor, bisphenol A, and diethylstilbestrol were classified as cytotoxic, but trichloroacetic acid was non-toxic. Classification accuracy was 90%. The mechanistic study showed that the cytotoxicities of butylparaben, propylparaben, octylphenol, and triclosan were induced by ER stress. The mRNA expressions of BiP, CHOP, and ATF4 were significantly higher following treatments with four EDCs compared to those after the control treatment. Compared to the control treatment, the mRNA levels of XBP1u and XBP1s increased significantly after butylparaben and propylparaben treatments, but did not increase with octylphenol and triclosan treatments. These results indicate that the EBT can be applied as an alternative toxicity test when evaluating the cytotoxicity of EDCs.

Glucocorticoid Effects on Cerebellar Development in a Chicken Embryo Model: Exploring Changes in PAX6 and Metalloproteinase-9 After Exposure to Dexamethasone

The developing cerebellum is vulnerable to effects of glucocorticoids and cerebellar dysfunction is associated with neurodevelopmental disorders (e.g. autism). Transcription factor PAX6 and matrix metalloproteinase-9 (MMP-9) are critical for normal cerebellar development and are highly expressed in migrating neurones. Alterations in MMP-9 and PAX6 are associated with altered cerebellar development. In the present study, we characterised the growth rate and development of the cortical layers, and further investigated how the levels of PAX6 and MMP-9, as well as glucocorticoid receptor (GR) and proliferating cell nuclear antigen (PCNA), change in the cerebellum during the foetal period [embryonic day (E)12-21] in chicken, which corresponds to the human perinatal period. Dexamethasone (DEX) was administered in ovo at E13 and E16, aiming to investigate how prenatal exposure to glucocorticoids interferes with normal development. DEX reduced foetal and cerebellar weight at E17 in a dose-dependent manner linked to a reduced level of PCNA and, over time, down-regulation of GR. We report that promoter activity of PAX6 and MMP-9 increased as a result of GR-stimulation in vitro. Prenatal DEX increased the protein level of PAX6 in a transient manner. PAX6 is reduced in mature granule neurones, and this occurred earlier in embryos exposed to DEX than in non-exposed controls. DEX exposure also led to a slow-onset down-regulation of MMP-9. Taken together, these findings indicate that excess prenatal glucocorticoid stimulation disturbs normal development of the cerebellum through mechanisms associated with reduced proliferation and accelerated maturation where PAX6 and MMP-9 play important roles.

Induced neural stem/precursor cells for fundamental studies and potential application in neurodegenerative diseases

Recent research has shown that defined sets of exogenous factors are sufficient to convert rodent and human somatic cells directly into induced neural stem cells or neural precursor cells (iNSCs/iNPCs). The process of transdifferentiation bypasses the step of a pluripotent state and reduces the risk of tumorigenesis and genetic instability while retaining the self-renewing capacity. This iNSC/iNPC technology has fueled much excitement in regenerative medicine, as these cells can be differentiated into target cells for re placement therapy for neurodegenerative diseases. Patients' somatic cell-derived iNSCs/iNPCs have also been proposed to serve as disease models with potential value in both fundamental studies and clinical applications. This review focuses on the mechanisms, techniques, and app lications of iNSCs/iNPCs from a series of related studies, as well as further efforts in designing novel strategies using iNSC/iNPC technology and its potential applications in neurodegenerative diseases.