Roche´s xCELLigence RTCA HT System: Fully-automated Measurement of Therapeutic Targets` Cellular Activity

"Label-free technologies have entered the stage of cellular drug discovery and high-throughput screening (HTS). For the measurement of G protein-coupled receptor (GPCR) activation electrical impedance represents an excellent universal readout technology, since different signaling pathways can be measured in one assay format using recombinant as well as primary cells. The recently developed xCELLigence RTCA HT Instrument from Roche Applied Science now allows to perform fully-automated impedance screens for GPCRs and other targets in the 384-well high-throughput format.
In a recent case study, Urs Lüthi and John Gatfield from Actelion Pharmaceuticals Ltd., Allschwil, Switzerland, integrated 2 RTCA HT (real-time cell analyzer for high-throughput) Instruments on an automated high-throughput screening platform from Agilent Technologies (Santa Clara, US). 263 antagonist hits of the orexin type 1 (Ox1) GPCR that had been identified in a classical calcium flux (FLIPR) HTS were screened for Ox1 inhibition in fully-automated RTCA HT assays. The overall performance, the quality of E-Plates 384 and intra- and inter-assay reproducibility were evaluated. 65% of the 263 antagonist hits were confirmed to be Ox1 receptor antagonists after impedance measurements. According to the researchers, the RTCA HT Instrument could be readily integrated into automated workflows and delivered a highly reproducible data set, making the RTCA HT Instrument a powerful screening technology. 

Compared to standard readout technologies one of the major advantages of label-free technologies is that cellular processes are measured in real-time kinetics in a non-invasive manner. The xCELLigence System uses gold electrodes at the bottom surface of microplate wells as sensors to which an alternating current is applied. Cells that are grown as adherent monolayers on top of such electrodes influence the alternating current at the electrodes by changing the electrical resistance (impedance). The degree of this change is primarily determined by the number of cells, strength of the cell-cell interactions, interactions of the cells with the microelectrodes and by the overall morphology of the cells."

MSE from Waters - the ultimate technology for reproducible profiling

"Waters mass spectrometers provide a method of data acquisition - known as MS^E - that records exact mass precursor and fragment ion information from every detectable component in a sample. This method rapidly alternates between two functions: the first acquiring low-energy exact mass precursor ion spectra, the second acquiring elevated-energy exact mass fragment ion spectra. Every mass is measured, and spectra for each component aligned in retention time. This patented method records data without discrimination or pre-selection so your samples are completely catalogued in a single analysis.



When compared to Data Directed Analysis (DDA), MS^E maximizes instrument duty cycle by ensuring that exact mass precursor and fragment ion information data are obtained for the entire peak complement of a chromatogram, making it ideal for fast analysis and narrow, rapidly eluting peaks. DDA results in both a loss of data in the MS mode when MS/MS data are being acquired, and poor duty cycle. MS^E data is collected fast enough to accurately define the LC peaks for every detectable component.



MS^E is faster than traditional MS followed by MS/MS analysis, and provides data that is not readily obtained by DDA, as both MS and MS/MS data for all detectable components in the chromatogram are generated. MS^E can generate both precursor and product ions in a single analytical run thereby eliminating the need to rerun the samples to obtain further MS/MS spectra. To see MS^E in action and hear what scientists have to say about it, visit www.waters.com/MS^E."