The best performing in vitro tests for estimation of acute oral systemic toxicity have been selected for pre-validation
30 December 2009
During 2009, a statistical analysis of all cytotoxicity data and organ-specific toxicity data was performed. The multivariate CART analysis revealed which in vitro assays were the best performing ones according to their reproducibility and reliability and most importantly, according to their potential to classify chemicals into the official acute oral toxicity classes (GHS and EU). The best performing assays (Table 1) will be challenged in the pre-validation study planned to take place during January-May 2010 with a new set of 33 coded chemicals. The final tiered testing strategy will be revealed after the retrospective analysis of its capacity to predict the official acute oral toxicity classes (GHS and EU). The impact of kinetic factors such as volume of distribution, protein binding, clearance, and oral absorption, together with estimated passage over the blood-brain barrier, will also be integrated in the final prediction model.
Table 1. The best performing in vitro assays, which were selected as candidates for the final tiered testing strategy, will be further evaluated in the pre-validation phase.
|
Selected assay |
Target (workpackage involved) |
|
The neutral red uptake assay using the3T3 fibroblast cell line (3T3/NRU) |
General basal cytotoxicity (WP2) |
|
The cytokine release assay using human whole blood (IL-1, IL-6, TNF-alpha) |
Haemotoxicity (WP 4) |
|
Cell differentiation in human cord blood-derived cells (CBC/CFU-GM) |
Haemotoxicity (WP 4) |
|
Gene expression (GFAP, HSP-32, MBP and NF-H) in primary rat brain aggregate cultures |
Neurotoxicity (WP 7.1) |
|
Uridine incorporation measuring the total mRNA synthesis in primary rat brain aggregate cultures |
Neurotoxicity (WP 7.1) |
|
Cytomic panel measuring oxidative stress (intracellular peroxidative activity, intracellular levels of superoxide anion, oxidized DNA base 8-oxoguanine) in HepG2, SH-SY5Y and A.704 cells |
New endpoints (WP 4) |
|
Cytomic panel for cytotoxicity screening (intracellular Ca2+ levels, mitochondrial membrane potential, plasma membrane potential) in HepG2, SH-SY5Y and A.704 cells |
New endpoints (WP 4) |
|
The MTT assay using primary rat hepatocytes |
Metabolism (WP 6) |
|
Kinetic parameters: volume of distribution, protein binding, clearance, and oral absorption (Caco-2 cells) for the estimation of the oral dose from the effective concentration observed in vitro |
Biokinetics (WP5) |
|
The estimation of compound passage through the blood-brain barrier using neuronal networks (for neurotoxicity assays) |
Biokinetics (WP5) |