1. tumor cell stock : 2.8 x 10^6 cells per 1 mL (Cell concentration = 2.8 x 10^6 cells/mL)
2. mice number : 2 mice
3. tumor cell number and volume when doing injection to a mouse: 1 x 10^6 cells per 0.015 mL
I have no idea which calculation is exactly right, but I guess the first explanation is correct.
The first calculation applied a proportional formula, and the seconde calculation applied a formula, which is 'concentration x volume = concentraion' x volume''.
The first calculation is
2.8 x 10^6 cells : 1 mL = 1 x 10^6 cells x 2 mice : x mL
x = (1 x 10^6 cells x 2 mice) / (2.8 x 10^6 cells) = 0.714 mL (714 uL)
Thus, I cannot make 1 x 10^6 cells in 0.015 mL. I should subculture the tumor cell again.
The second calculation is
2.8 x 10^6 cells x x mL = 1 x 10^6 cells x 2 mice x (0.015 mL x 2)
x = (1 x 10^6 cells x 2 mice x (0.015 mL x 2)) / 2.8 x 10^6 cells = 0.021 mL (21 uL)
Thus, I prepare 1 x 10^6 cells in 0.015 mL for 2 mice by mixing 21 uL cells and 9 uL PBS.
Which one is correct?
Would you please check the calculation?
Hello Seulki Choi
The first calculation is right.
Pipette up and down the tumor cell stock, and aspirate 714ul of the cell suspension from the stock (containing 1ml) into a new microfuge tube. Centrifuge the tube at 800-1000g for 5 minutes and discard the supernatant taking care not to disturb the cell pellet. Tap the cell pellet (2 x10^6 cells), and add 100ul of sterile PBS. Place the cells on ice. Since you have two mice, you may remove 50ul of cell suspension in another microfuge tube. So, each tube will now have 1 x 10^6 cells in 50ul.
It is recommended that the cells for injection be combined with 50ul of Matrigel right before injection. So, cell suspension and Matrigel may be mixed in the ratio of 1:1 for total volume of 100 µL. Using a 1cc syringe, draw up 50ul Matrigel and mix into the cells suspended in PBS in the two tubes just prior to the start of injections.
Do remember to keep this cell prep on ice to prevent the Matrigel from solidifying prior to injection. Use of Matrigel will help to facilitate tumor formation and growth.
You have enough cells from the stock to inject into two mice. No need to subculture the tumor cells again.
Best.
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