Countess 3 FL Automated Cell Counter

In addition to counting cells, the fluorescence capabilities of the Countess 3 FL instrument are often used to assess cell viability, apoptosis, transfection efficiency, and fluorescent protein expression. But the applications extend to any cellular parameters that are autofluorescent or can be labeled using fluorescent dyes. You’ll find data illustrating cell culture quality control, CAR-T cell screening, CRISPR-Cas9 editing efficiency, and other fluorescence applications in Sample Data.

Cell viability. Assessing cell viability is a key step in daily cell culture and is required for accurate and efficient downstream processing. The Countess 3 FL fluorescence options offer a sensitive and specific viability check that can be performed quickly and easily prior to downstream sample analysis.

Although trypan blue is widely used for viability assessment in brightfield cell counting, it can alter cell morphology in certain cases. For example, when dead mouse PBMCs are stained with trypan blue, they can expand and sink to a different focal plane than live cells, complicating accurate detection and counting. As a fluorescence alternative, Invitrogen ReadyCount Green/Red Viability Stain contains acridine orange and propidium iodide (AO/PI) in an optimized combination. Fluorescent staining provides great sensitivity and greater specificity of live/dead status in a mixed cell population without altering the morphology of the cell.

With the fluorescence capabilities of the Countess 3 FL Automated Cell Counter, you can easily visualize fluorescent proteins and perform apoptosis or proliferation assays in your cell culture room. 

The Countess 3 FL instrument has two optional fluorescence channels, which will detect fluorescent colors determined by the insertion of individual light cubes. With 14 interchangeable light cubes to choose from, the Countess 3 FL instrument is not limited to detection of cells expressing GFP and RFP. 

The Invitrogen EVOS LED light cubes that power these fluorescence applications on the Countess 3 FL provide more than 50,000 hours of brilliant (yet adjustable) illumination that remains constant with minimal degradation over time. Cost-efficient, environmentally friendly, and spectrally optimized, EVOS LED light cubes are designed for precise control, minimal maintenance, and exceptional reliability.

Each cube contains an LED, illuminating optics, and filters. Light cubes are user-interchangeable and automatically detected by the Countess 3 FL system for plug-and-play ease.

Tip: Light cubes are not included with the Countess 3 FL cell counter to allow customization based on dyes and fluorescent proteins used. 

Choose light cubes with spectra that match the dyes and counting applications you want to use. Light cubes are easy to swap in and out and can be purchased at any time to meet new application requirements. A wide range of dyes is supported.

Although many researchers choose GFP and RFP for fluorescent protein detection, there are 14 different EVOS LED Light Cube choices. DAPI is a traditionally used nuclear dye. The table shows common dyes detected by seven popular light cubes.

Suppose you are interested in measuring both apoptosis and viability of cells in a population. You can use an apoptosis indicator that measures caspase activation, such as CellEvent Caspase-3/7 Green Detection Reagent along with the EVOS GFP 2.0 light cube. Additionally, use a viability dye such as SYTOX Red Dead Cell Stain with the EVOS Cy5 2.0 light cube to measure dead cells that have progressed past apoptosis. This staining combination, along with the two EVOS light cubes, offers a fast and simple multiplex method to obtain apoptosis and viability data.

Fluorescence staining can provide rich data on cells, especially in heterogeneous samples, but commercial stains can be difficult to mix, titrate, and apply for optimal performance. Invitrogen ReadyCount reagents are bench-stable fluorescent stains that are pre-optimized for use with Countess 3 FL Automated Cell Counter. 

ReadyCount reagents can be used to stain specific nucleated cells within mixed populations, reducing complexity and improving count-to-count and sample-to-sample reproducibility when matched to the appropriate EVOS light cube. Simply mix 10 µL of cell sample with 10 µL of stain, pipet the solution into a Countess chamber or reusable slide, and insert the slide into the instrument.