A team at the German Cancer Research Center in Heidelberg, Germany, has used the Xcelligence MP from Roche to quantify cell proliferation, without the need for tagging or modifying sampled cells.
According to Roche, RNA interference studies are particularly suitable for high-throughput screening.
However, endpoint analyses only provide a snapshot of the analysed cellular phenotype, as it is not possible to measure developmental changes over time.
As reported in the July 2011 edition of Plos One Online, the researchers showed that the measurement of impedance strength is positively correlated with the number of cells attached to electrodes.
Impedance measurements reflect not only cell number but also the quality of the cells' interaction with their substrate, making this technology a sensitive and reliable way to assess cell status, including cell morphology, cell adhesion and cell viability.
The Heidelberg German Cancer Center research team integrated the Roche Xcelligence MP instrument into a high-throughput workflow for assaying the effects of large numbers of small interfering RNA (siRNA) transfections.
They used a human siRNA library to perform a whole-kinome screen, targeting 779 kinases and 80 cell cycle genes to analyse cell proliferation in real time by monitoring the dynamics of the cellular responses after high-throughput gene knockdown.
The team's findings showed that Xcelligence system measurements correlate with results obtained using, in parallel, conventional endpoint analyses, in particular Promega's Celltiter-Blue and Roche's WST-1 cell proliferation reagent for assaying cell viability, as well as qRT-PCR for quantifying gene expression.
However, the dynamic data obtained with the Xcelligence system allowed the team to identify the timing after transfection where the effect was maximal and to sort genes according to these time points.
Stefan Wiemann, one of the authors of the study and head of the division of molecular genome analysis at the centre, said: 'We have carried out a human kinome RNAi screen using Xcelligence with electrical impedance as output.
'This screen has confirmed previously identified inhibitor genes, as well as activators of cell proliferation.
'Our data establish the technology of the Xcelligence system as a novel tool amenable for high-throughput screening, opening new avenues in the dynamic cellular analysis of phenotypes induced by RNAi and other perturbations,' he added..
The Xcelligence MP instrument uses proprietary software and E-Plates 96 to measure electronic cell impedance using sensor electrodes.
Computer-controlled signal generation and automatic frequency scanning enable the continual precise detection of changes in cell behaviour using 96-well culture plates.