Exosomes are nanometer-sized vesicles, secreted from most cell types, with 
documented immune-modulatory functions. Exosomes can be purified from cultured 
cells but to do so effectively, requires maintenance of cells at high density in 
order to obtain sufficient accumulation of exosomes in the culture medium, prior 
to purification. Whilst high density cultures can be achieved with cells in 
suspension, this remains difficult with adherent cells, resulting in low 
quantity of exosomes for subsequent study. We have used the Integra CELLine 
culture system, originally designed for hybridoma cultures, to achieve a 
significant increase in obtainable exosomes from adherent and non-adherent 
tumour cells. Traditional cultures of mesothelioma cells (cultured in 75 cm(2) 
flasks) gave an average yield of 0.78 microg+/-0.14 microg exosome/ml of 
conditioned medium. The CELLine Adhere 1000 (CLAD1000) flask, housing the same 
cell line, increased exosome yield approximately 12 fold to 10.06 microg+/-0.97 
microg/ml. The morphology, phenotype and immune function of these exosomes were 
compared, and found to be identical in all respects. Similarly an 8 fold 
increase in exosome production was obtained from NKL cells (a suspension cell 
line) using a CELLine 1000 (CL1000) flask. The CELLine system also incurred ~5.5 
fold less cost and reduced labour for cell maintenance. This simple culture 
system is a cost effective, useful method for significantly increasing the 
quantity of exosomes available from cultured cells, without detrimental effects. 
This tool should prove advantageous in future studies of exosome-immune 
modulation in cancer and other settings.