cells culture - (Jun/04/2008 )

Hi,
I'm a new on cells culture, I hope some one can answer me below questions.
1) How do I measure cell viability? Is there a quantitative method I can records cell viability?

3) Are there methods I can learn to help me detect contamination?
How do I know that a cell line I've been growing for 2 weeks or that I'm about to freeze down again is pure? Is there an easy way to do that or is that an analysis that someone else does?

Thanks very much for your time,

1. The easiest way I know of to measure viability is to count cells stained with Trypan Blue on a hemocytometer before subculturing them. If the cells are clear, they're good; if they're blue, they're dead and you don't count them. If you're trying to see if your cells grew or didn't grow in the presence of something else, the MTT proliferation assay is the quantitative method I'm most familiar with, though there are others.

2. ?

3. Bacterial and Fungal contamination is usually plain to see, with a marked increase in turbidity of the media and cells which are not your culture visible when the flasks are viewed under the inverted-phase microscope. If your culture is contaminated by another cell line, then good luck figuring that out - that's much easier to prevent by good aseptic technique. Testing for mycoplasmas is a pain, but neccessary - the PCR tests are not reliable, and neither are most other assays for them that don't involve growing in/on selective media/agar.

Hope this helps.

Thanks so much for Thesquire's response! That was very helpful.

. .. Nature Protocol's description was helpful.