I have been culturing HUVEC and sometimes the cells look stressed and stop dividing. When this happens, they don't recover after I change the medium. What may be causing this problem? Expired medium (2 months ago)? Reusing (washed and sterelised) plastic tubes? Reusing (washed and sterelised) serological glass pippets? I have tried coating and not coating with gelatin. It didn't make difference. Can someone give any idea?
This is the protocol I use for subculturing:
-wash with versene
-incubate with trypsin
-inactivate trypsin with DMEM 5% FBS
-centrifuge 800rpm 5min
-resuspend in EGM2
-seed the cells