The Roche Diagnostics Xcelligence system can be used to reduce the number of laboratory animals used for in vivo testing of suboptimal compounds that ultimately fail at later stages of drug testing.
A recent study from Roche Pharma and Roche Applied Science describes a comprehensive workflow of in vitro techniques, including real-time cell analysis, biochemical assays and gene expression analyses for hepatotoxicity assessment.
Hepatotoxic effects of the tested compounds were monitored using the Xcelligence system to generate Cell Index (CI) profiles that quantitate the onset and progress of compound-induced cell death.
Compared to routinely used biochemical endpoint assays, the Xcelligence system showed a higher sensitivity 24 hours post-treatment.
Resulting kinetic profiles monitored toxicity from the beginning to end of the experiment; profiles such as this are not possible using endpoint assays.
Continuous CI recording quantifies cytotoxicity identifying the optimal time point for IC50 calculations.
CI profiles revealed dose-dependent hepatocyte responses to the tested compounds as early as six hours post-treatment.
Researchers investigated hepatotoxic effects by gene expression analysis at these early time points.
Whole genome microarray analysis revealed a significant reproducible change in gene expression six hours post-treatment, coinciding with the onset of cell death found in the Xcelligence system data.
Subsequent quantitative RT-PCR for a subset of selected genes revealed a significant change in gene expression six hours after compound administration, indicating early onset of gene regulation within the first hours post-treatment.
The results of this study emphasise the added value of the described workflow of real-time cell analysis, biochemical endpoint assays and gene expression analyses.
Continuous monitoring using the Xcelligence system identified modest cellular effects, providing a versatile way for pinpointing times for downstream proteomic and genomic analyses.
Using Roche Nimblegen microarrays for appropriately timed molecular analysis assures meaningful and reproducible whole genome expression data for identifying new target genes and possible biomarkers.
Gene expression analyses using Universal Probelibrary assays are also now available as pre-tested real-time ready assays.
Combining the Xcelligence system with Roche endpoint assays and this generation of Roche gene expression assays is said to improve the predictive quality of early safety evaluations that may go on to reduce current levels of animal testing in the future.
