Cellometer: Disposable Hemacytometer From Nexcelom Bioscience

The utilization of cultured mammalian cells in biological or biomedical research will almost assuredly necessitate counting the cells at some time or another. For routine cell counting, the most commonly used tool is the hemacytometer. Although quite simple in concept, the hemacytometer is a precision instrument that permits an accurate estimation of cell number. It consists of a sturdy glass base somewhat larger than a microscope slide and containing two microscale grids etched into the center portion. Overlaying the gridded areas with a coverslip forms a chamber of precisely defined depth so that cells in a defined volume (usually 0.1 µl) can be counted visually with the aid of a phase-contrast microscope. While the hemacytometer is perfect for counting cells from one or two cultures, it tends to become somewhat of a pain as the number of cultures increases. This is because the hemacytometer must be disassembled, rinsed with water and ethanol, and dried before being used again. Fortunately, there is a cell counting device that eliminates the between-use manipulations of the conventional hemacytometer.

The Cellometer (Nexcelom Bioscience, Lawrence, MA) is a disposable counting gadget modeled after the hemacytometer. Each Cellometer device contains two counting chambers mounted on a glass or plastic base the size of a microscope slide. Since the grid pattern and size are essentially identical to that found on conventional hemacytometers, the transition from using the hemacytometer to the Cellometer is seamless. To use the device, you simply dilute the cell culture to the appropriate level and pipette 15-20 µl into one of the counting chambers. Each chamber has two ports, one for introduction of the sample and one for venting of trapped air in the chamber. The Cellometer can be used either with the vital dye trypan blue or without.

I have recently used the Cellometer for counting cultured myeloma cells and found it to be very convenient and easy to use. One issue I have with the device is that for the glass-based model it is impossible to have both the cells and the grid in sharp focus at the same time. Apparently, this is because the grid pattern is on the underside of the cover of the counting chamber while the cells settle to bottom of the chamber. According to an employee of Nexcelom, the plastic-based Cellometers have the grid on the bottom of the counting chamber, allowing both the cells and the grid to be in the same focusing plane.

Although the Cellometer can be ordered directly from Nexcelom, it is also available from vendors such as ISC BioExpress and Bellco. Package sizes range from a box of 5 to a case or 500 and the cost per device varies with package size. For example, 5 glass-based devices cost $25 and a box of 100 plastic-based ones is $300 from ISC BioExpress. If you are going to use the Cellometer frequently, the cost adds up quickly. However, I have found that the Cellometer is reusable. After counting, I hold the Cellometer over the sink and squirt ddH₂O through the counting chamber followed by 70% ethanol. I then allow the device to air dry in a drawer. I have reused a glass-based Cellometer 3 or 4 times and have had no problems. I haven’t tried this with the plastic ones but I presume they could also be reused.