Overconfluent stock flasks - is this a problem? - (Jan/21/2011 )

Would keeping overconfluent stock flasks affect the cells? We normally keep our flasks at 100%, and sometimes they get very tightly packed. Would it be more advantageous to keep the flasks at a lower confluency or does it not make a difference? Thanks!

Yes, it is a problem as the cells behave differently at high confluence. You should be splitting and maintaining your cells at less than 70-80% confluent.

totally aree, it will affect the growth dynamics of the cells and hence affect whatever assay/methods you are using them for. best bet is to bin them and bring some more up from fresh stocks then split them regularly. for best effects use T75 flasks as this encourages you to split them every 3-4 days or so.

Appreciate the response from both of you. Any idea why the cells behave differently at higher confluencies?

Because in nature this is a signal for the cells to stop growing (contact inhibition), some immortalised cells have overcome this, but there are still effects from high confluence.