Question

After taking an aliquot of J558 suspension cells from your T75 culture flask, you dilute this aliquot in Trypan Blue in a 1:1 ratio. After loading the cells on the hemocytometer you obtain the following counts:

	Transparent cells	Blue cells
Quadrant 1	62	0
Quadrant 2	58	0
Quadrant 3	61	1
Quadrant 4	57	0
Quadrant 5	59	0

1) What is the cell viability (%)?

2) What is the average number of living cells per quadrant?

3) What is the cell density in the original culture?

4) What is the total number of cells in your T75 culture flask?

Answer 1

1) Cell viability = (Number of cell transparent cells/ Total number of cells) X 100

= (162+ 258+ 361+ 457+ 559/1798) X 100 = (1797/1798) X 100 = 99.9%.

Cell viability usually calculated by counting the transparent cells because, a live cell will take the tryphan blue dye.

2. Average number of living cells = (162+ 258+ 361+ 457+ 559)/5 = 359.4.

3. Cell density = ( Number of cells counted/Number of quadrants counted)Xdilution factorX10⁴

⁼ {(162+ 258+ 361+ 457+ 559/1798) / 5} X 2 X 10⁴ = (1797/5) X2 X 10000 = 359.4 X2X10000 = 7,188,000 cells/ml.

Sample was diluted with tryphan blue in 1:1 rati. So, the dilution factor will be 2.

4. Usually T75 flask will hold 8-15 ml of media. Here the begining volume of the cell suspension was not given to calculate the total number of cells in T75 flask.