Dynamic cultivation of human mesenchymal stem/stromal cells for the production of extracellular vesicles in a 3D bioreactor system
Ciarra Almeria, René Weiss, Maike Keck, Viktoria Weber, Cornelia Kasper, Dominik Egger
Abstract
Abstract Purpose 3D cell culture and hypoxia have been demonstrated to increase the therapeutic effects of mesenchymal stem/stromal cells (MSCs)-derived extracellular vesicles (EVs). In this study, a process for the production of MSC-EVs in a novel 3D bioreactor system under normoxic and hypoxic conditions was established and the resulting EVs were characterized. Methods Human adipose-derived MSCs were seeded and cultured on a 3D membrane in the VITVO® bioreactor system for 7 days. Afterwards, MSC-EVs were isolated and characterized via fluorescence nanoparticle tracking analysis, flow cytometry with staining against annexin V (Anx5) as a marker for EVs exposing phosphatidylserine, as well as CD73 and CD90 as MSC surface markers. Results Cultivation of MSC in the VITVO® bioreactor system demonstrated a higher concentration of MSC-EVs from the 3D bioreactor (9.1 × 10 9 ± 1.5 × 10 9 and 9.7 × 10 9 ± 3.1 × 10 9 particles/mL) compared to static 2D culture (4.2 × 10 9 ± 7.5 × 10 8 and 3.9 × 10 9 ± 3.0 × 10 8 particles/mL) under normoxic and hypoxic conditions, respectively. Also, the particle-to-protein ratio as a measure for the purity of EVs increased from 3.3 × 10 7 ± 1.1 × 10 7 particles/µg protein in 2D to 1.6 × 10 8 ± 8.3 × 10 6 particles/µg protein in 3D. Total MSC-EVs as well as CD73 − CD90 + MSC-EVs were elevated in 2D normoxic conditions. The EV concentration and size did not differ significantly between normoxic and hypoxic conditions. Conclusion The production of MSC-EVs in a 3D bioreactor system under hypoxic conditions resulted in increased EV concentration and purity. This system could be especially useful in screening culture conditions for the production of 3D-derived MSC-EVs.