cell viability with PI staining - (Oct/20/2014 )

Hi, 

I want to test the cell viability by PI.

But i have only found the protocol of cell cycle.

In the protocol, it have to add 70% EtOH to fix cell and add RNase A with PI staining solution.

Should i do the steps if i just want to test viability?

Should i do a trypam blue stain and visually counting to compare it?

Thanks a lot.

PI is not transported across viable cell membranes, so it will only penetrate dead/non-viable cells. Fixing your cells will kill them and, seeing as you are using ethanol, will probably permeabilize the membranes such that PI will penetrate. As a viability stain, you wouldn't fix your cells, but I'm not sure exactly the process.

To check viability, just add PI to your sample immediately before measuring. Dead cells will take it up immediately so you can then discriminate live and dead populations on FACS.