Unhealthy Passaging? - passaging cells too much... will they go bad? (Aug/29/2006 )

I have some HepG2, NIH-3T3 and 4T1 cells that I've been passaging a lot for almost 3 months... They look fine to me but a colleague said that cells go bad from too much passaging. Is that true? I thought it might be the case for more sensitive cell lines but less so for cancer cells. I'm not sure if I am right so I wanted to check with someone who is more familiar in this area than I am.

Thanks!

No fixed answer. More like a case specific thing.

every cell type is different and the number of passages vary according to cell type. But all cell lines after a certain number of passages have to b discarded and lower passaged ones have to b thawed out.

my experience is that cells get exausted after numbers of passages, the morphology may look fine, but you never know (especially if you are doing functional assay). I usually maintain a cell line no more than 1 month.

I also use cancer cells and it is definitely reccomended to not passage them too much - mutations just add up. I once compared the many passaged cells to ones that were bought from the ATCC and although the morphology was similar the protein and gene expression was VERY different.