Cell Counting and Cell Viability

Cell counters are used to count live and/or dead cells in a culture. Cell counting can be used to determine cell concentration prior to cell passage, assess cell viability following drug treatment, accurately count every cell in the sample, qualitatively determine cell health, count subpopulations and capture, analyze and manipulate data.

Types of Cell Counters:

Manual cell counters are also referred to as hemocytometers .

Automatic cell counters use three different types of technology:

• Coulter counters: A probe that contains two electrodes separated by a small hole is inserted into a solution containing the particles to be counted. As particles pass through the hole, they disrupt the impedance between the two electrodes. The impedance is related to particle size, enabling particle size distribution to be measured. This correlates to mobility, surface charge, and concentration of the particles. This method cannot distinguish live from dead cells.
  
  
• Direct imaging: Cells are stained and suspended on a slide, and directly counted. Using a dye that stains nuclei is a common method to mark cells for counting. Some stains can be used for viability analyses, as they are actively excluded from live cells and stain only dead cells.
  
  
• Flow cytometry: Cells are suspended in a stream of fluid and passed by an electronic detection apparatus for counting. Flow cytometry is a rapid method of classifying cell type percentages, but most cytometers cannot directly provide the concentration or absolute count of cells in a sample.