Hello,
We have just started growing cryopreserved primary human epithelial keratinocytes provided from Thermo Fisher, and three days after culture initiation we noticed a yellow floating mass in all of the flasks we plated (please see attached picture).
Could it be contamination? If not, what is it? Should we discard the cultures?
Thank you in advance for your answers.
Mouna
Could be dead cells that have detached, wash a few times with complete medium or pbs then or sub culture to very low 1:20 or 1:30 and wait a day or three... it apears again it may be a resistant contamination, if you have pen/strep or g418 pressure.
These cells grow well and live cells should attach, dont let cultures get too confluent bf subculturing.
The first culture you get with low passage number, geow to a giant culture or tons of t-75s and freeze back 10 to 20 tubes with 10 million or so per freeze. Just in case.
I do hope its not contamination, you could call fisher?
Best wishes!
Thank you Charles. I will try washing the culture and seeing if the mass remains. I will also call Fisher, perhaps they have an explanation.
Mouna
Hi Mouna - the mass looks very similar to the cells you are plating (which is a good sign).
Do you use pen/strep in your media? When plating adherent cells, I will always change the media the next day to remove any cells that are dead or have not adhered (as it is inevitable that some will become stressed and die during the process).
Replace the media, and if the mass returns/grows do not open the plate again and get rid of the cultures.
I am assuming that the plates that you are using are specifically tissue culture plates and are sterile :)
Good luck!
Rachel
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