conditioned medium for ischaemia study - (Nov/29/2012 )

Hi,
I am hoping to condtion media with one cell type in three conditions - normoxia, hypoxia (0.1% 02) and Hypoxia/ischaemia (0.1% 02, no glucose, no serum). I then want to concentrate this media and add it to wells with another type of cell which will be exclusively in hypoxia/ischaemia and observe the effects.
My problem is that the media in the first and second groups (normoxia and hypoxia) will contain FBS, since this media will not be conditioned under ischaemic conditions. Is it possible to remove the FBS from this media through dialysis, centrifugation etc but still preserve the secreted proteins which are present due to the conditioning phase?

I realise this is a long shot...

I doubt it, the secreted stuff is largely protein, as is serum...