Contamination or dead cells? - (Nov/29/2014 )

Hi All,

I'm relatively new to cell culture work. I mainly work with HEK293 cells. After thawing the cells, a couple days ago, I changed the media yesterday and subcultured them today. I didnt see any signs of contamination when splitting the cells. However, around 20 mins after I returned them back to the incubator, I rechecked them and found large clumps of cells (they appear brownish in colour). I just want to make sure that this is not a sign of fungal contamination.

I read somewhere that these are likely to be clumps of dead cells but I was wondering if anyone working with HEK293 has encountered this before.

Many thanks in advance

20 min is about the time taken for a single division cycle of E coli.... it takes a little longer than that  for contamination to become apparent. These are clumps of cells, unless you have gross contamination of your cell culture.