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In vitro Morphogenesis in Developmental Toxicity Testing: Assay Validation and the Search for Teratogenic Mechanisms.

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Title:In vitro Morphogenesis in Developmental Toxicity Testing: Assay Validation and the Search for Teratogenic Mechanisms.
Authors:Warkus, Erica L. L.
Contributors:Developmental & Reprod Biology (department)
Keywords:Erica Warkus
Developmental Toxicity
In Vitro Gastrulation
Embryoid Body Morphogenesis
Validation of Stem Cell Models
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Date Issued:May 2018
Publisher:University of Hawaiʻi at Mānoa
Abstract:Teratogens are chemicals that can cause birth defects in the developing embryo during pregnancy. Major structural birth defects affect 2-5% of children, but the etiology of this developmental error is often unknown. Exposure to teratogens (chemicals that cause birth defects) during gestation may play a causative role in many of these congenital defects. Therefore, it is important to identify teratogenic chemicals before pregnant women are exposed to them, but there is no easy, reliable test to determine potential teratogenicity of pharmaceutical drugs or industrial chemicals (pesticides, herbicides, solvents, etc.). Current developmental and reproductive toxicity (DART) testing uses millions of pregnant animals in outdated, inefficient regulatory studies. Embryonic stem cell-based in vitro tests (EST) produce faster, clearer results and have the potential to revolutionize DART testing, but they often lack the biologic complexity created during embryonic gastrulation and morphogenesis. The embryo is most sensitive to teratogenic exposures during the first three to eight weeks of fetal life. During this time, the process of morphogenesis shapes nearly all three-dimensional (3-D) organs and tissue structures in the embryo. Many of the common birth defects (e.g., neural tube closure defects and cardiac septal defects) are caused by disruptions in this vital process. Since morphogenesis drives the formation of fetal structures and is often affected by teratogenic drugs, a screen for potential teratogens should incorporate similar 3-D structural complexity, but this is a common deficit of in vitro teratogenicity tests. Aggregated P19C5 stem cells spontaneously form “embryoid bodies” (EBs) and recapitulate the germ layer differentiation and structural remodeling that occur during embryonic gastrulation and morphogenesis. Exposure to teratogens disrupts EB morphology, making P19C5 morphogenesis a sensitive indicator of developmental toxicity. In this research project, I validated the P19C5 system as a morphology-based teratogen-screening assay and demonstrate that the P19C5 assay can be used to investigate teratogenic mechanisms that cause structural defects. We expect that this test will allow us to accurately identify chemicals that may cause fetal malformations and help us understand the mechanisms of teratogenic chemicals in order to reduce the number of children born with preventable birth defects.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018.
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Developmental and Reproductive Biology

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