Frequently asked questions

"MSC" is used in two ways in the literature: mesenchymal stem cell and mesenchymal stromal cell. The International Society for Cell & Gene Therapy has recommended "stromal" because most preparations contain a mixed population that does not strictly meet stem-cell criteria. The acronym remains the same.

No. It is an umbrella term for any culture format that allows cells to organise in three dimensions rather than as a flat layer on plastic. The most common formats are spheroid culture (cells aggregate into clusters), scaffold culture (cells grow on a porous biomaterial), hydrogel culture (cells suspended in a soft polymer network), and bioreactor culture (for example hollow-fiber or stirred-tank systems). Each has tradeoffs in scalability, reproducibility, and ease of characterisation.

MSCs in their native tissue are surrounded by other cells and extracellular matrix and receive cues from all directions. A growing body of work shows that 2D plastic culture changes their gene expression, paracrine output, and EV cargo away from the in-tissue baseline, while 3D formats restore some of those features. See the 3D vs 2D page for details.

Both are extracellular vesicles. Exosomes (typically ~30–150 nm) form inside multivesicular bodies and are released when those bodies fuse with the plasma membrane. Microvesicles (typically ~150 nm to 1 µm) bud directly from the plasma membrane. The size ranges overlap, and most isolation methods recover a mixed population. The MISEV2018 guidance recommends using "small extracellular vesicles" as a default term unless biogenesis can be unambiguously demonstrated.

The secretome is the entire set of molecules a cell releases into its environment — soluble proteins (cytokines, chemokines, growth factors), lipids, nucleic acids, and membrane-bound vesicles. For MSCs the secretome includes immunomodulatory factors, pro-angiogenic factors, matrix proteins, and EVs carrying microRNA, mRNA, and protein cargo. See the secretome page.

Reports in the peer-reviewed literature frequently describe higher yield per cell from 3D systems — particularly hollow-fiber bioreactor and spheroid formats — compared with matched 2D cultures, but the magnitude depends on the specific bioreactor, harvest schedule, isolation method, and cell source. There is no single fold-change that applies universally.

No. EVs are sub-cellular particles enclosed by a lipid bilayer; they cannot replicate, do not contain a nucleus, and are an order of magnitude smaller than the cells that produce them. They carry a subset of the parent cell's molecular content (proteins, lipids, RNAs) but are biologically and regulatorily distinct.

The MISEV2018 guidance recommends reporting at minimum: the isolation method, particle count and size distribution (e.g. by nanoparticle tracking analysis), and the presence of canonical markers (such as CD9, CD63, CD81, syntenin, TSG101) and absence of intracellular contaminants (such as calnexin, GM130). Direct imaging by cryo-electron microscopy is also commonly included. See the exosomes page.

No. There are several distinct stem-cell families — embryonic, induced pluripotent (iPSC), haematopoietic, neural, and mesenchymal among them — each with different biology, regulatory status, and clinical application. MSCs are tissue-resident multipotent stromal cells most commonly isolated from bone marrow, adipose tissue, or umbilical cord.

Conditioned medium is the cell culture supernatant after a defined incubation period — the bulk liquid containing everything the cells released during that window plus residual medium components. EVs can be purified from conditioned medium by ultracentrifugation, tangential flow filtration, size-exclusion chromatography, or affinity capture. A study that reports "secretome" effects may be referring to either whole conditioned medium or purified EVs; the distinction matters when comparing studies.

The research library on this site lists representative peer-reviewed citations with DOI and PubMed links. For broader literature, search PubMed for terms such as "3D MSC culture", "spheroid mesenchymal secretome", "3D-derived extracellular vesicles", or "hollow-fiber bioreactor MSC exosomes".

No. 3DMSCs.com is an independent educational resource. It does not endorse, review, or sell any product, and is not affiliated with any commercial supplier. See the about and disclaimer pages.