Counting Human Neural Stem Cells

Passaging Human Neural Stem Cells

Note: Please refer to the Passaging Human Neural Stem Cells article on how to detach and resuspend the cells. http://www.jove.com/index/Details.stp?ID=263

Preparing the Cell Suspension for Counting

1. Place 25 µl of 0.4% Trypan Blue solution and 20 µl of cell media into an eppendorf tube.
2. Resuspend the cells to be counted by gently tapping the tube containing the cells in a known volume of media to create a homogenous suspension. Place 5 µl of cells into the eppendorf tube from the previous step. This step dilutes the cell concentration by a factor of 10.
3. Place the cover glass on the hemacytometer, and load about 11-12 µl of the cell suspension.
   
   
   
   

Counting Cells in the Hemacytometer

1. Observe the entire grid of the hemacytometer in a phase contrast microscope. Focus on one quadrant of the grid (such as the one in red).
   
   
   
   
2. Dead or dying cells will appear blue because their membrane has been damaged and are not able to exclude the Trypan blue dye. Viable cells will not appear blue and will be surrounded by a “halo” of light in phase contrast (will be “phase-bright”).
3. Count the number of viable cells in one quadrant (area 1 mm²). You can also determine cell viability by dividing the number of viable cells by the total number of cells. Count cells in 3-4 random quadrants and determine the average number of cells per quadrant. Since the volume of a quadrant is known to be 10^-4 ml or 0.1 µl, the concentration of cells can be determined
   
   
   
   
   
   
4. You can use the following shortcut to determine the #cells/µl:
   
   
   
   Total # of cells in tube =# cells/µl X µl in tube

This protocol describes a straightforward and rapid way to determine the cell concentration for a variety of experiments involving cells. Using the shortcut described in 3d, one can quickly and accurately determine the cell concentration and total cell number in a given volume.