Is this contamination? (I'm a beginner!) - (Sep/04/2014 )

Hi all,

I've been growing CHO-S cells in static culture for a little while now (doing some cloning). On a whim I recently took a look at an old culture (10+ days) and noticed strange leaf-shape objects in the culture. What do you all think it is? Is it a contaminant? These cells are fairly clumpy/unhealthy so I'm hoping it is somehow a product of this. Thanks all. Image attached.z

Did you just leave the cutlure sitting there for 10+ days? I don't know anything about CHO-S cells but all the cell types I've ever cultured required much more frequent passaging. My guess is the medium became depleted about a week ago and the cells have been left sitting in metabolites.

I think that the things you identify as leaf-shapes are adherent cells - cells which have adhered to the bottom of the vessel.

The ATCC has a lot of information on cell cutlure that you should peruse to make sure you're doing the right thing both in general and for your specific cell types.

The leaf-shaped things are in all probability adherent cells, I can only agree with the above post. It is not a contaminant. Other than that, the pictures looks pretty much like a sphere culture in which the cells have not been passaged adequately, an indicator is the strong brown colour notably in the midst of the "spheres" where nutrient levels are generally the lowest. The cells in there are probably beginning to be necrotic and you can also see that several spheres are beginning to form large clumps.