Good morning everybody,
I'm looking for help to identify strange ?contaminants? in my bone marrow MSC cell culture (P1). I do precise that cells were bought and unfrozen in T25 flask. Here is what we noted :
- When culturing the cells for 2 weeks after unfrozen, a "mist" of black dots has developed at the same time.
- These dots are non-motiles and seem to be tightly adhered to the cells and to the flask. It really looks like bacteria contamination but I don't think it is that.
- Rinse with PBS did not allow to eliminate them.
- MSC growth seems not to be affected by this veil as cells are more numerous day after day and the morphological aspect also seemed to be ok.
- Cell medium color is absolutely clear and normal and did not turn turbid at all.
- Trypsine use to detach the cells did not have any effect on them, they do not detach at all.
Other cells are cultured currently but only MSCs display this veil.
Did someone already have seen something like that ? Is it a contamination ? If yes, what kind and how to get rid of this ?
I attached pictures at magnificence x5, x10 and x20 to illustrate the problem.
Thank you for any kind of information. Hope I did not forget something to clearly explain the problem. Please let me know if you have any questions, I will try to answer it.
Thanks in advance !!
Hello Sandra Roumani
From the picture, on comparing the relative size of the black dots with the cells, it seems to be bacterial contamination. Since you mentioned these are immotile and do not get removed after trypsinization, it probably can be Staphylococcal contamination. If it is possible for you, please click a picture at 100x and provide the same. I hope you are using antibiotics in your culture medium. If not, then supplement PenStrep, gentamicin, or even amoxicillin to remove this contaminant. These antibiotics won't harm your cells, but you will have to perform multiple passages under antibiotic pressure to remove this contaminant. Hope it helps you :)
Hello Sandra Roumani
- The problem had been seen before in two papers
1- Got black swimming dots in your cell culture? Identification of Achromobacter as a novel cell culture contaminants.
2- Preliminary evidence of a new microbial species capable of sustainable intracellular survival and transfer in mammalian cell lines.
- I guess, it is a bacterial contamination and your stock of cells should be further examined. I hope this will help you.
That's right, it seems from the pictures that it's a bacterial contamination, but your explanation regarding the color of the medium and other things really raises suspicion.
It may be remnants of the residues of the medium or it may be cells of a type of yeast or something else.
Try the following
Pass the medium through a 0.22 micron filter (all contents of the medium including FBS). Before adding the medium, wash it well several times with PBS.
Use a cocktail of antibiotics of ampicillin, penicillin, gentamicin, streptomycin and a fungal antibiotic, use it at a concentration twice the concentration you are currently using.
I wish you good luck
- Badges
- Science topic