Cell Viability

A Bright Field Cell Viability Assay in the cellTRAY® CT-1000 Live Cell Imaging System

M. Powell, A. Cabasug, L. Higashi

The process of apoptosis involves a cascade of cytoplasmic and nuclear events that result in a series of morphological changes and eventually cause the demise of the cell. Apoptosis can be initiated by a variety of different stimuli that lead to a convergence of biochemical signaling pathways into a common collection of executioner molecules. A growing area of current research involved trying to determine the sequence of events and the interdependencies involved in apoptosis signaling. The goal of this research is to identify the commitment step (point of no return) in the process. Knowledge of this event can help develop therapeutic approaches to delaying and controlling cellular death.

Time lapse images of trypan blue cell viability study
Time lapse images of trypan blue cell (Sigma Aldridge Trypan Blue Solution) viability study performed on drosophila KC cells treated with Valinomycin. Time duration of photos was 4 hours. Photos acquired on inverted Nikon TE2000, 10x objective, and OEM 1.4 MP CCD bright field camera

In vitro cell culture model systems and screening assays for cell death have become important tools for determining the chronology of events resulting in apoptosis. In vitro model systems have also been proven useful in screening for inhibitory or stimulatory compounds that affect specific enzyme systems or affect the general process of cell death and apoptosis. Information derived from these assays can indicate whether a cell population that has been exposed to an experimental stimulus is healthy or dying, actively dividing or in stasis, or has committed to an apoptotic pathway.

Trypan Blue is a stain used to differentiate viable and nonviable cells. Cells are very selectable when it comes to allowing or baring compounds to pass through the cell membrane. The blue stain is easily visible, and cells can be counted using a light microscope. Using Nanopoint's cellTRAY CT-1000 Live Cell Imaging System, a protocol has been developed for performing cell viability assays with the vital stain Trypan blue.

Nanopoint’s cellTRAY, a novel micro-fabricated live cell containment device, was designed specifically for imaging live cells. The device enables the precise containment of cells in an optical glass substrate the size of a standard 1"x3" microscope slide, comprised of a micro-array of thousands of precision etched wells for isolating cells (or small groups of cells) for experimentation and imaging. Cells can be observed before and after replication allowing the researcher to monitor the response of cells to other stimuli.

The cellTRAY also contains microfluidic channels that allow life support and reagents to be administered to the various wells. The significant advantage of the cellTRAY over current systems is its size (small physical footprint) and the number of fluidically isolated regions containing individual microwells that can all contain multiple live cells. This means cells are loaded (or seeded) into micron-sized openings on the surface of the cellTRAY and assays require much less reagents than what is currently used for plate-based assays, making it a low cost alternative to current well-plate technology.


  1. “Ways of dying: Multiple Pathways to Apoptosis” Jerry M. Adams, Genes and Development, 2003, 17, 2481-2495
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CT-1000 Live Cell Imaging System cellTRAY Live Cell Containment Device