Application of Modern Toxicology Approaches for Predicting Acute Toxicity for Chemical Defense (2015) / Chapter Skim
Currently Skimming:
4 Assays for Predicting Acute Toxicity
4 Assays for Predicting Acute Toxicity
Pages 51-79
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 51... ...
built on the early publications and gave rise to a variety of large-scale initiatives to see how in vitro testing methods can be used to predict human toxicity. To implement the strategy outlined in the NRC report, a collaboration was formed between the National Toxicology Program (NTP)
|
From page 52... ...
to screen chemicals of interest to DOD for acute toxicity. IN VITRO ASSAYS Numerous in vitro screening assays have been developed for measuring specific biological activities of chemicals in specific organs or cell types with an eye to elucidating mechanisms of action.
|
From page 53... ...
FIGURE 4-1 Intended target families and subfamilies for the ToxCast program. The number of assays for each intended target is represented by the sizes and font sizes of the orange nodes.
|
From page 54... ...
. There is an increasing shift away from cell lines toward cell-based assays that use cell types that are more physiologically relevant, such as animal or human primary cells, and human induced pluripotent stem (iPS)
|
From page 55... ...
Notably, several cytotoxicity assays -- an MTT assay in primary rat hepatocytes; a cytotoxicity panel that measures intracellular Ca2+ levels, mitochondrial membrane potential, and plasma membrane potential in HepG2, SHSY5Y and A.704 cells; and a basal cytotoxicity NRU assay in BALB/3T3 cells -- generated data of sufficient quality to be considered in future acute-toxicity testing strategies (Kinsner-Ovaskainen et al.
|
From page 56... ...
For example, the ACuteTox project included four cytokine secretion assays performed on primary white blood cells isolated from human blood and four assays that measured synthesis of neuronal and glia proteins, at the mRNA level, from aggregates of primary cells derived from rat brain (Kinsner-Ovaskainen et al.
|
From page 57... ...
To address the limitation, researchers have been developing approaches for coculture of multiple cell types or for cultures of whole organs as slices or cell aggregates. Those approaches are collectively referred to as organotypic models.6 The discussion below highlights a few organ systems that are relevant to acute toxicity of chemicals.
|
From page 58... ...
The systems use primary cells cultured at an air–liquid interface, and they model airway function better than traditional submerged tissue culture. A recent paper evaluated the models relative to each other and to two conventional submerged tissue-culture systems for their ability to predict rodent lung toxicity of 19 chemicals (Sauer et al.
|
From page 59... ...
. The continued reliance on 2-D cultures and hepatoma-derived cell lines is problematic because testing in more robust in vitro models would probably generate more-predictive data.
|
From page 60... ...
Limitations and Needs for Improvement of Organotypic Models Additional organotypic models have been developed for the heart, kidney, and skeletal muscle. Organotypic models have high potential for predicting acute toxicity and potentially can recapitulate the metabolism and biological activity of a chemical.
|
From page 61... ...
It contains 959 somatic cells, including about 300 neurons that are microscopically visible. The developmental cell lineage and the neural wiring diagram of C
|
From page 62... ...
. Limitations and Needs for Improvement of Nonmammalian In Vivo Animal Models Nonrodent animal models have the potential to assist in characterizing the acute toxicity of chemicals.
|
From page 63... ...
EMERGING TECHNOLOGIES The drive to develop nonanimal methods for toxicity testing is still in its infancy, and new technologies are continually being developed. Most are aimed at commercial applications, particularly for safety assessment in the pharmaceutical and cosmetics industries, but a subset of the new technologies will also be useful for predicting acute toxicity.
|
From page 64... ...
. A recently created database includes expression signatures for 1,000 genes, using the L1000 assays, for treatment of tens of cell lines with thousands of chemicals (Duan et al.
|
From page 65... ...
Thus, the long-term potential for application of iPS cells to toxicity testing is high. Nevertheless, many hurdles must be overcome, including development of methods for reliable differentiation of iPS cells into cell types that are relevant to acute toxicity.
|
From page 66... ...
In Vitro Systems to Study the Role of Metabolism in Toxicity Potential A variety of in vitro model systems have been developed to study metabolism and include "precision-cut tissue slices, subcellular fractions such as the microsomal fraction, primary cells in suspension, primary monolayers of cells in culture, continuous cell lines, immortalized primary cells, liver-derived cell lines re-expressing biotransformation enzymes and geneticallyengineered cell lines expressing biotransformation enzymes" (Combes et al.
|
From page 67... ...
. Primary cells that are derived directly from animal or human tissues are more metabolically competent than immortalized cell lines but have much shorter half-lives and require much more care to be sustained for toxicity screening.
|
From page 68... ...
. BOX 4-1 ACuteTox Testing Strategy The goal of the EU ACuteTox project was to evaluate whether regulatory animal tests for acute systemic toxicity could be replaced with a combination of in vitro assays.
|
From page 69... ...
differentiated cells. In addition, proliferative cell lines have a reduced ability to metabolize parent chemicals.
|
From page 70... ...
. FINDINGS AND RECOMMENDATIONS Finding: On the basis of the results of HTS programs, in vitro assays have demonstrated some predictive value for acute toxicity; therefore, an in vitro screening approach for predicting the potential for chemicals to cause acute, debilitating injuries is theoretically feasible.
|
From page 71... ...
2008. Tox21: Putting a Lens on the Vision of Toxicity Testing in the 21st Century [online]
|
From page 72... ...
2008. Cell lines: A tool for in vitro drug metabolism studies.
|
From page 73... ...
2003. The Registry of Cytotoxicity: Toxicity testing in cell cultures to predict acute toxicity (LD50)
|
From page 74... ...
2008. Characterization of diversity in toxicity mechanism using in vitro cytotoxicity assays in quantitative high throughput screening.
|
From page 75... ...
2012. Evaluation of drugs with specific organ toxicities in organ-specific cell lines.
|
From page 76... ...
2010. Variable toxicological response to the loss of OXPHOS through 1-methyl-4-phenylpyridinium-induced mitochondrial damage and anoxia in diverse neural immortal cell lines.
|
From page 77... ...
2010. The future of toxicity testing: A focus on in vitro methods using a quantitative high throughput screening platform.
|
From page 78... ...
2013. Use of the Cultex® Radial Flow System as an in vitro exposure method to assess acute pulmonary toxicity of fine dusts and nanoparticles with special focus on the intra- and inter-laboratory reproducibility.
|
From page 79... ...
Assays for Predicting Acute Toxicity 79 Yen, J., S Donerly, E.D.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.