Event:298

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Event Title

Vascular, insufficiency
Short name: Vascular, insufficiency

Key Event Overview

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AOPs Including This Key Event

AOP Name Event Type Essentiality
VEGF Signaling and Vascular Disruption Leading to Adverse Developmental Outcomes KE Strong

Taxonomic Applicability

Name Scientific Name Evidence Links

Level of Biological Organization

Biological Organization

How this Key Event works

The cardiovascular system is the first functional organ system to develop in the vertebrate embryo, reflecting its critical role during normal development and pregnancy. Blood vessels are key regulators of organogenesis by providing oxygen, nutrients and molecular signals [Maltepe et al. 1997; Chung and Ferrara, 2011; Eshkar-Oren et al. 2015].

Vascular development commences in the early embryo with in situ formation of nascent vessels from angioblasts, leading to a primary capillary plexus (vasculogenesis). After the onset of blood circulation, the primary vascular pattern is further expanded as new vessels sprout from pre-existing vessels (angiogenesis). Both processes, vasculogenesis and angiogenesis, are regulated by genetic signals and environmental factors dependent on anatomical region, physiological state, and developmental stage of the embryo. The developing vascular network is further shaped into a hierarchical system of arteries and veins, through progressive effects on blood vessel arborization, branching, and pruning (angioadaptation). These latter influences include hemodynamic forces, regional changes in blood flow, local metabolic demands and growth factor signals.

Disruptions in embryonic vascular patterning-adaptation may result in adverse pregnancy outcomes, including birth defects, angiodysplasias and cardiovascular disease, intrauterine growth restriction or prenatal death. Some chemicals may act as potential vascular disrupting compounds (pVDCs) altering the expression, activity or function of molecular signals regulating blood vessel development and remodeling. Critical pathways involve receptor tyrosine kinases (e.g., growth factor-signaling), G-protein coupled receptors (e.g., chemokine signaling), and GPI-anchored receptors (e.g. uPAR system). Embryonic vascular disruption has been implicated in the etiology of human birth defects associated with medications taken by women of child-bearing potential (WOCBP) [van Gelder et al. 2009] and thalidomide teratogenesis in animal studies [Therapontos et al. 2009; Vargesson et al. 2015].

How it is Measured or Detected

Methods that have been previously reviewed and approved by a recognized authority should be included in the Overview section above. All other methods, including those well established in the published literature, should be described here. Consider the following criteria when describing each method: 1. Is the assay fit for purpose? 2. Is the assay directly or indirectly (i.e. a surrogate) related to a key event relevant to the final adverse effect in question? 3. Is the assay repeatable? 4. Is the assay reproducible?

An in vitro signature for potential vascular disrupting chemicals (pVDCs) was mined for developmental toxicity based on ToxCast Phase-I dataset [Kleinstreuer et al. 2011]. The pVDC signature was subsequently expanded into a comprehensive Adverse Outcome Pathway (AOP) framework for vasculogenesis and angiogenesis [Knudsen and Kleinstreuer, 2011]. This has since been applied to the ToxCast inventory to rank order 1060 chemicals for validation testing [McCollum et al. 2016; Tal et al. 2016; Knudsen et al. 2016]. As such, a chemical’s potential to disrupt vascular patterning, remodeling, or utero-placental circulation could be a class predictor of developmental toxicity solely based on the ToxCast in vitro data in combination with our understanding the embryology behind vascular development.

Methods to examine the longer-term consequences of embryonic vascular disruption used trangenic zebrafish as an experimental model of vascular development [Tal et al. 2014]. Transgenic zebrafish that express enhanced green fluorescent protein in blood vessels were used to visualize and quantify blood vessel formation during early development. Intersegmental vessels (ISVs) were selected as a phenotypic readout of angiogenic vessel formation and used to generate a quantitative in vivo model of developmental vascular toxicity. While previous studies have employed automated image based phenotypic evaluation of ISV sprout length, assay sensitivity is unclear. Tran et al. screened 1,280 phamacologic compounds and identified one novel ISV hit in addition to two control compounds [20]. Yozzo et al. screened 10 known cardiovascular toxicants through an image analysis pipeline that included ISV sprout length quantitation and reported no chemical-mediated effects, but significant inter-plate variability in ISV length [21]. In comparison, Vogt et al. deployed automated ISV quantitation to identify concentration dependent decrements in a number of ISV metrics following exposure to a known anti-angiogenic reference compound, but the assay was not expanded to test pharmacological agents or environmental chemicals [22]. We also previously reported a quantitative assay to detect ISV sprout growth, but the assay relies on confocal imaging of individual larvae and is not amenable for screening purposes [23]. Here, we generated a quantitative assay capable of detecting relatively subtle changes (~8%) in ISV length relative to control sprouts.


The quantitative relationship between vascular insufficiency and developmental toxicity is measured in animal models. The relationship to the MIE:VEGFR2, inhibition has been demonstrated in transgenic zebrafish carrying a reporter gene for green fluorescent protein expression [Tal et al. 2014]. exists between the

Evidence Supporting Taxonomic Applicability

References

Chung AS, Ferrara N. Developmental and pathological angiogenesis. Annual review of cell and developmental biology. 2011;27:563-84. PubMed PMID: 21756109.

Eshkar-Oren I, Krief S, Ferrara N, Elliott AM, Zelzer E. Vascular patterning regulates interdigital cell death by a ROS-mediated mechanism. Development (Cambridge, England). 2015 Feb 15;142(4):672-80. PubMed PMID: 25617432.

Jin SW, Beis D, Mitchell T, Chen JN,Stainier DY. Cellular and molecular analyses of vascular tube and lumen formation in zebrafish. Development. 2005 132: 5199-209.

Kleinstreuer NC, Judson RS, Reif DM, Sipes NS, Singh AV, Chandler KJ, et al. Environmental impact on vascular development predicted by high-throughput screening. Environmental health perspectives. 2011 Nov;119(11):1596-603. PubMed PMID: 21788198. Pubmed Central PMCID: PMC3226499.

Knudsen TB, Kleinstreuer NC. Disruption of embryonic vascular development in predictive toxicology. Birth defects research Part C, Embryo today : reviews. 2011 Dec;93(4):312-23. PubMed PMID: 22271680.

Maltepe E, Schmidt JV, Baunoch D, Bradfield CA, Simon MC. Abnormal angiogenesis and responses to glucose and oxygen deprivation in mice lacking the protein ARNT. Nature. 1997 Mar 27;386(6623):403-7. PubMed PMID: 9121557.

McCollum CW, Vancells JC, Hans C, Vazquez-Chantada M, Kleinstreuer N, Tal T, Knudsen T, Shah SS, Merchant FA, Finnell RH, Gustafsson J-A, Cabrera R and Bondesson M (2016) Identification of vascular disruptor compounds by a tiered analysis in zebrafish embryos and mouse embryonic endothelial cells. (submitted).

Tal T, Kilty C, Smith A, LaLone C, Kennedy B, Tennant A, McCollum C, Bondesson M, Knudsen T, Padilla S and Kleinstreuer N (2016) Screening for chemical vascular disruptors in zebrafish to evaluate a predictive model for developmental vascular toxicity. (submitted).

Therapontos C, Erskine L, Gardner ER, Figg WD, Vargesson N. Thalidomide induces limb defects by preventing angiogenic outgrowth during early limb formation. Proceedings of the National Academy of Sciences of the United States of America. 2009 May 26;106(21):8573-8. PubMed PMID: 19433787. Pubmed Central PMCID: 2688998.

van Gelder MM, van Rooij IA, Miller RK, Zielhuis GA, de Jong-van den Berg LT, Roeleveld N. Teratogenic mechanisms of medical drugs. Human reproduction update. 2010 Jul-Aug;16(4):378-94. PubMed PMID: 20061329.

Vargesson N. Thalidomide-induced teratogenesis: history and mechanisms. Birth defects research Part C, Embryo today : reviews. 2015 Jun;105(2):140-56. PubMed PMID: 26043938.