I have a general question regarding the isolation of extracellular vesicles (EVs). I have read in various papers that EVs isolated from cell culture media are initially grown in media supplemented with regular FBS for 24 hours, achieving approximately 70% confluency. Following this, the cells are washed with PBS three times before switching to exosome-depleted FBS for a 48-hour incubation. This step is intended to prevent contamination of the samples with EVs from the FBS. I am wondering if it is possible to grow my cells from the beginning using media supplemented solely with exosome-depleted FBS, rather than following the initial steps with regular FBS.
Dear Dr. Bianca Mercado Velez,
It is necessary to first grow HEK293 cells in media supplemented with regular FBS and then transfer them to media with exosome-depleted FBS. This is because the cells need time to adapt to the absence of these exosomes when switching to exosome-depleted FBS. Transferring the cells gradually allows them to adjust to the new environment, minimizing stress and maintaining cell viability.
When you initially grow cells in regular FBS, it provides the necessary nutrients and growth factors for cell proliferation. Then, when you transfer the cells to the media containing exosome-depleted FBS, it ensures that the cells are properly prepared for your experiment where the focus is on the cells' own exosome production and not those derived from the serum.
This approach will help cells adapt to the culture conditions before introducing the altered serum.
Regards,
Malcolm Nobre
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