Hi, I have been trying to isolate exosomes from human MSC by ExoQuick kit for a while and haven't obtained any pellet so far ( step 4 in protocol - centrifuge mixture at 1500 g at 30 mins).

So far I have tried:

- from 80% to 100% confluence on the day of change to serum-free medium

- collecting cell culture media (CCM) after 24,48,72h

- collecting CCM from 1, 4 or 8 dishes ( tried to increase volume)

Doing BCA I get concentrations  below 0.3ug/ul. I don't use exosome depleted FBS, I just simply don't use any FBS in medium as serum-free medium.

When I switched to HeLa cells, I got a nice pellet even from 1 dish (10 ml of CCM). Is there any way to increase exosomal yieald,concentration from MSC?

Thank you