Extracellular vesicles from 3D MSC culture
Extracellular vesicles (EVs) are membrane-enclosed particles released by virtually all cells. In MSC research, EVs have attracted interest because they carry many of the same nucleic-acid and protein cargoes that mediate MSC paracrine effects, while being smaller, easier to store, and more amenable to characterisation than whole cells.
Terminology
The current consensus reference is MISEV2018, the Minimal Information for Studies of Extracellular Vesicles guidance from the International Society for Extracellular Vesicles. MISEV recommends:
- Using the broad term "extracellular vesicles" as the default rather than committing to a biogenesis subtype unless evidence supports it.
- Reporting size distribution (e.g. by nanoparticle tracking analysis), particle count, and marker profile.
- Documenting the isolation method, since different methods yield overlapping but distinct populations.
"Exosome" specifically refers to small EVs of endosomal origin, typically 30–150 nm in diameter, formed from intraluminal vesicles of multivesicular bodies and released when those bodies fuse with the plasma membrane. In practice, most preparations called "exosomes" in the literature are mixed small-EV populations and the MISEV term small EVs is more accurate.
How EVs are characterised
| Method | What it measures |
|---|---|
| Nanoparticle tracking analysis (NTA) | Particle count and size distribution from light scattering of moving particles |
| Tunable resistive pulse sensing (TRPS) | Particle-by-particle size and concentration through a calibrated pore |
| Cryo-electron microscopy | Direct imaging of vesicle morphology and bilayer membrane |
| Western blot / flow cytometry | Presence of canonical EV markers (e.g. CD9, CD63, CD81, TSG101, syntenin) and absence of contaminants |
| Mass spectrometry | Protein cargo profile |
| Small-RNA sequencing | microRNA and other small-RNA cargo |
What changes with 3D production
Across published comparisons of EVs harvested from MSCs grown in 2D versus 3D systems, the most commonly reported differences include:
Yield per cell
Several groups have reported substantially higher EV yields per cell from 3D systems — particularly hollow-fiber bioreactor and spheroid formats — compared with matched 2D monolayer controls. Reported fold-changes vary widely with the specific bioreactor, harvest schedule, and isolation method.
Cargo profile
Small-RNA sequencing comparisons report shifts in the relative abundance of specific microRNAs in 3D-derived EVs, with multiple studies highlighting enrichment of microRNAs associated with anti-inflammatory or matrix-modulating pathways. Protein cargo studies have similarly reported shifts in tetraspanin abundance and in matrix-associated proteins.
Size distribution and surface markers
Some reports observe a tighter size distribution in 3D-derived preparations, especially when bioreactor culture is paired with tangential flow filtration. Canonical EV markers (CD9, CD63, CD81) are typically retained.
Functional readouts
In in vitro assays — for example wound-healing scratch assays, endothelial tube formation, macrophage polarisation — EVs from 3D-cultured MSCs have been reported to show higher activity per particle than those from matched 2D cultures. These findings should be read in context: assay endpoints, isolation methods, and dosing schemes vary, and translation from cell-based assays to clinical outcomes requires further controlled study.