Roche's xCELLigence System: Key Technology for Analysing Cells and Drug Mechanisms

As shown in a number of experiments with different cell lines, the impedance-based xCELLigence System offers distinct and important advantages over traditional end point assays in research and is suitable for label-free and dynamic monitoring of the biological status of the cells, including cell number, viability, morphology and assessment of drug interactions with target cells.

First, the avoidance of labels allows for more physiologically relevant assays, which save on time, labour, and resources. In addition, by recording the entire course of drug interaction with particular cells during research, dynamic monitoring enables the user to gain a better understanding of the mode and mechanism of drug interaction. Finally, since each compound or drug has its own characteristic profile with respect to its interaction with target cells, impedance-based technology may be useful for determining the mechanism of action of drugs with unknown targets.

The use of cell-based assays is crucial for understanding the efficacy, specificity, permeability, solubility, stability and mechanism of drug interaction with target cells. It is therefore important that researchers choose the right platform for cell-based assays in order to thoroughly and efficiently exploit the potential of compound libraries.

Most formats designed for analysis of cell proliferation and viability are single end-point assays such as WST-1, XTT, MTT assays as well as fluorescence microscopy. These techniques have several limitations, involving labelling, destruction of the cells, and lack of quality control when they are used to determine cell viability before and after exposure to a compound.

Based on this knowledge, xCELLigence allows label-free dynamic monitoring of cell proliferation and viability in real-time. The technique utilizes an electronic readout of impedance to non-invasively quantify cellular status in real-time. Cells are seeded in E-Plate microtiter plates, which are integrated with microelectronic sensor arrays. The interaction of cells with the microelectrode surface generates a cell-electrode impedance response, which not only indicates cell viability but also correlates with the number of the cells seeded in the well.

The xCELLigence System is a joint development from Roche Applied Science and ACEA Biosciences in San Diego. ACEA´s RT-CES^® system is the predecessor of the xCELLigence system.