Producing vesicle-free cell culture additive for human cells extracellular vesicles manufacturing
Résumé
A new paradigm has emerged recently, which consists in shifting from cell therapy to a more flexible acellular
“extracellular vesicle (EV) therapy” approach, thereby opening a new and promising field in nanomedicine.
Important technical limitations have still to be addressed for the large-scale production of clinical-grade EV.
Cells are cultured in media supplemented with human platelet lysate (hPL) (xenogenic-free) or GMP-grade fetal
calf serum (FCS). However, these additives contain high amounts of EV that cannot be separated from cellsecreted
-EV. Therefore, cells are generally maintained in additive-free medium during the EV secretion
phase, however this can substantially limit their survival. In the present work, we developed a method to prepare
vesicle-free hPL (EV-free hPL) or vesicle-free FCS (EV-free FCS) using tangential flow filtration (TFF). We show a
very efficient EV depletion (>98%) for both pure hPL and FCS, with a highly conserved protein content. Culture
medium containing our EV-free additives supported the survival of human bone marrow MSC (BM-MSC). MSC
could survive at least 216 h, their conditioned medium being collected and changed every 72 h. Both the cell
survival and the cumulative EV production were substantially higher than in the starving conditions classically
used for EV production. In EV-free hPL containing medium, we show that purified EV kept their morphologic and
molecular characteristics throughout the production.
Finally, we tested our additives with 3 other cell types, human primary Endothelial Colony Forming Cells
(ECFC) and two non-adherent human cell lines, Jurkat and THP-1. We confirmed that both EV-free hPL and FCS
were able to maintain cell survival and EV production for at least 216 h.
Our method provides therefore a new option to help producing large amounts of EV from virtually any
mammalian cells, particularly those that do not tolerate starvation. This method can apply to any animal serum
for research and development purpose. Moreover, EV-free hPL is clinical-grade compatible and allows preparing
xenobiotic-free media for massive therapeutic EV production in both 2D (cell plates) and 3D (bioreactor) setting.