long-term toxicity

/Tag:long-term toxicity

Long-term In Vitro Toxicity Models: Comparisons Between a Flow-cell Bioreactor, a Static-cell Bioreactor and Static Cell Cultures

Patricia Pazos, Salvador Fortaner and Pilar Prieto

In vitro long-term toxicity testing is becoming an important issue in the field of toxicology, and there is a need to develop new model systems that mimic human chronic exposure and its effects. The aim of this work was to test two long-term in vitro toxicity systems which are available, a flow-cell bioreactor (Tecnomouse) and a static cell bioreactor system (CELLine CL 6-well), and to compare them with the use of conventional cell culture flasks. A human cell line, Int 407, was exposed to cadmium chloride (CdCl2; 10-7-10-8M) for 4 weeks. Cell numbers and cell viabilities were determined by the trypan blue (TB) exclusion assay and from exclusion of propidium iodide (PI) as determined by flow cytometry; and cell viability and metabolic activity were determined by the MTT assay. In addition, total protein determination and cadmium uptake measurements were performed. The results obtained with TB and PI exclusion did not show clear differences in cell viability with increasing CdCl2 concentration. However, in the static cell-culture systems, an increase in MTT reduction was found at low concentrations of CdCl2. Expression of heatshock protein (Hsp27 and Hsp70) increased differently, depending on the CdCl2 concentration applied and the system used. In summary, of the two bioreactors, the CELLine CL 6-well bioreactor was shown to be the more efficient system for performing long-term cytotoxicity studies. It is easy to handle, it permits the assessment of several endpoints, and sufficient replicates can be made available.
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Barriers, Nephrotoxicology and Chronic Testing In Vitro

Pilar Prieto

In many organs of the human body, there are effective physiological barriers which contribute to regulation of the uptake, transport and secretion of endogenous and exogenous materials. ECVAM is involved in the development of several in vitro models for detecting damage to various barriers, including, the renal epithelium, the intestinal barrier, and the blood-brain barrier, after acute and chronic exposure to chemicals and products of various kinds. Long-term toxicity testing is an important issue in toxicology. At present, there are no generally accepted in vitro models available for replacing chronic testing in animals. Under chronic exposure conditions, the cellular response is greater than that which can be predicted in the standard cytotoxicity models. Therefore, the approach to predicting chronic toxicity will need to involve more-complex in vitro models. Several currently available in vitro long-term toxicity systems are under evaluation.
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An Integrated Decision-tree Testing Strategy for Repeat Dose Toxicity with Respect to the Requirements of the EU REACH Legislation

Christina Grindon, Robert Combes, Mark T.D. Cronin, David W. Roberts and John F. Garrod

This paper presents some results of a joint research project conducted by FRAME and Liverpool John Moores University, and sponsored by Defra, on the status of alternatives to animal testing with regard to the European Union REACH (Registration, Evaluation and Authorisation of Chemicals) system for the safety testing and risk assessment of chemicals. The project covered all the main toxicity endpoints associated with REACH. This paper focuses on the use of alternative (non-animal) methods (both in vitro and (in silico) for repeat dose (sub-acute, sub-chronic and chronic) toxicity testing. It reviews the limited number of in silico and in vitro tests available for this endpoint, and outlines new technologies which
could be used in the future, e.g. the use of biomarkers and the ‘omics’ technologies. An integrated testing strategy is proposed, which makes use of as much non-animal data as possible, before any essential in vivostudies are performed. Although none of the non-animal tests are currently undergoing validation, their results could help to reduce the number of animals required for testing for repeat dose toxicity.
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An Integrated Decision-tree Testing Strategy for Repeat Dose Toxicity with Respect to the Requirements of the EU REACH Legislation

Christina Grindon, Robert Combes, Mark T.D. Cronin, David W. Roberts and John F. Garrod

This paper presents some results of a joint research project conducted by FRAME and Liverpool John Moores University, and sponsored by Defra, on the status of alternatives to animal testing with regard to the European Union REACH (Registration, Evaluation and Authorisation of Chemicals) system for the safety testing and risk assessment of chemicals. The project covered all the main toxicity endpoints associated with REACH. This paper focuses on the use of alternative (non-animal) methods (both in vitro and in silico) for repeat dose (sub-acute, sub-chronic and chronic) toxicity testing. It reviews the limited number of in silico and in vitro tests available for this endpoint, and outlines new technologies which
could be used in the future, e.g. the use of biomarkers and the ‘omics’ technologies. An integrated testing strategy is proposed, which makes use of as much non-animal data as possible, before any essential in vivostudies are performed. Although none of the non-animal tests are currently undergoing validation, their results could help to reduce the number of animals required for testing for repeat dose toxicity.
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