Osteosarcoma cell culture problem - (Oct/31/2012 )

Hi anybody deals with osteosarcoma cell culture regularly? I have been culturing osteosarcoma cells (143B control and several cybrids) recently and can see very small black particles floating in the media. They increase in number over time however, the media seems to be clear (At least in the naked eye) and not yellow. I use filtered media and grow the cells in a flask
Does anybody know if the cells secrete any kind of particles in the media???
Any kind of help will be highly appreciates.
Thanks in advance.

do they vibrate? just look closer and let me know.

What do you mean by 'vibrate' it is floating in the media so anytime I handle the flasks It moves around.

don't move the plate around then...., some bacterial contamination slightly vibrate. It is clearly visible under 20X maginification.

Do be aware, though, that non-living particles can vibrate too. It's called Brownian motion.

There are quite a few threads on here about the black dots in tissue culture phenomenon, maybe try searching them and see if you can find someone with the same problem as you and what they did about it

yeah but some of those little ones proliferate and form grape-like clusters in few days.

No they do not form any grape like clusters or any known bacterial foration. However I think they might be vibrating but not sure. But the problem is the media does not get cloudy or yello as it should be in a bacterial contamination

some cells die and float in media. They won't have the morphology of living cells and look different. could be that?