culturing caco 2 cells - problems interacted with during the culturing (Mar/25/2011 )

Hi every one, i've been growing caco2 cells and have encountered problems such as a floating cell line within the adhering caco 2 cells. It does not look anything like fungal contamination or so forth and is also differnt from the caco 2 cells. The cells were thawed at 20% FBS,DMEM and then changed to 5% FBS, DMEM but when floating cells appeared cells were then changed to 10%FBS,DMEM because i thought it had something to do with the FBS concentration.
That did not seam to help and i also did a couple of washes but still no luck. So was wondering if any of you guys perheps know what this cells are and how i can remove them.

How quickly did you change the FBS concentration? If you went straight from growing (not from frozen) in 20% to growing in 5%, then they are probably dying, or at least, very unhappy cells. You may need to lower the FBS concentration slowly over several passages (a process called weaning).