For researchers performing invasion and migration assays, the CIM-Plate 16 used with the xCELLigence Real-Time Cell Analyzer (RTCA) DP instrument from Roche Applied Science, a business area of Roche Diagnostics, offers a means to monitor cellular responses in real time, without exogenous labels, through impedance-based technology. The CIM-Plate 16 provides a kinetic cell-response profile throughout an experiment, detailing the onset and rate of invasion and migration. This information can help researchers understand processes that current endpoint experiments are unable to address.
The study of cell invasion and migration is of great importance to enable a better understanding of underlying biological and molecular mechanisms. The new CIM-Plate 16 device detects real-time invasion and migration of cells without the use of labels.
Cell invasion is the intrusion on and destruction of adjacent tissues, particularly with respect to cancer cells. Cell migration is the movement of cells from one area to another, generally in response to chemical signal; it is important in diverse physiological and pathological processes, including embryonic development, cell differentiation, wound healing, immune response, inflammation, and notably, cancer metastasis.
Conventional methodologies for migration detection are endpoint and label-based assays. One of the more commonly used methods is the Boyden chamber (also called trans-well migration assay), whereby cells placed in inserts are allowed to invade and migrate through an artificial microporous membrane into lower chambers containing a given chemoattractant.
There are drawbacks to this approach. The migrated cells (typically attached on the reverse side of the membrane) must be stained with chemical dyes or labeled with fluorescent molecules. In most cases, the membrane is removed from the insert, and then the stained or labeled cells are counted manually using a microscope or evaluated using a spectrometer.
This labor-intensive process limits throughput and, as a result of labeling the cells, may alter gene-expression profiles and lead to intra-assay variability because of differences in labeling efficiency. Additionally, cell counting by means of microscopy may not be accurate, often resulting in inconsistent and irreproducible migration data.
In contrast to conventional methods, the Roche xCELLigence RTCA DP Instrument provides kinetic information about cell migration by dynamically recording the entire cell migration and invasion process in real time without labeling cells, considerably improving invasion and migration assay quality.
The RTCA DP Instrument uses the CIM (cellular invasion/migration)-Plate 16, which features microelectronic sensors integrated onto the underside of the microporous polyethylene terephthalate membrane of a Boyden-like chamber (Figure 1).
As cells migrate from the upper chamber through the membrane into the bottom chamber in response to chemoattractant, they contact and adhere to the electronic sensors on the underside of the membrane, resulting in an increase in impedance. The impedance increase correlates to increasing numbers of migrated cells on the underside of the membrane, and cell-index values reflecting impedance changes are automatically and continuously recorded by the RTCA DP Instrument (Figures 2 and 3). Therefore, cell-migration activity can be monitored via the cell-index profile.