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Updated: Mar 24, 2026
Membrane Remodeling of Giant Vesicles in Response to Localized Calcium Ion Gradients
Published on: July 16, 2018
MSC secretes at least 3 EV types each with a unique permutation of membrane lipid, protein and RNA
Ruenn Chai Lai1, Soon Sim Tan1, Ronne Wee Yeh Yeo1
1A*STAR Institute of Medical Biology, Singapore.
Abstract:
Mesenchymal stem cell (MSC), a widely used adult stem cell candidate for regenerative medicine, has been shown to exert some of its therapeutic effects through the secretion of extracellular vesicles (EVs). These homogenously sized EVs of 100-150 ηm exhibited many exosome-like biophysical and biochemical properties and carry both proteins and RNAs. Recently, exosome-associated proteins in this MSC EV preparation were found to segregate primarily to those EVs that bind cholera toxin B chain (CTB), a GM1 ganglioside-specific ligand, and pulse-chase experiments demonstrated that these EVs have endosomal origin and carried many of the exosome-associated markers. Here, we report that only a fraction of the MSC EV proteome was found in CTB-bound EVs. Using Annexin V (AV) and Shiga toxin B subunit (ST) with affinities for phosphatidylserine and globotriaosylceramide, respectively, AV- and a ST-binding EV were identified. CTB-, AV- and ST-binding EVs all carried actin. However, the AV-binding EVs carried low or undetectable levels of the exosome-associated proteins. Only the ST-binding EVs carried RNA and EDA-containing fibronectin. Proteins in AV-binding EVs were also different from those released by apoptotic MSCs. CTB- and AV-binding activities were localized to the plasma membrane and cytoplasm of MSCs, while ST-binding activity was localized to the nucleus. Together, this study demonstrates that cells secrete many types of EVs. Specifically, MSCs secrete at least 3 types. They can be differentially isolated based on their affinities for membrane lipid-binding ligands. As the subcellular sites of the binding activities of these ligands and cargo load are different for each EV type, they are likely to have a different biogenesis pathway and possibly different functions.
Insights
Mesenchymal stem cells secrete diverse extracellular vesicles (EVs) with distinct properties and functions. Researchers identified three EV types in MSCs using specific lipid-binding ligands, revealing differences in cargo and biogenesis.
Area of Science:
- Cell Biology
- Biochemistry
- Regenerative Medicine
Background:
- Mesenchymal stem cells (MSCs) are key for regenerative medicine, with therapeutic effects mediated by secreted extracellular vesicles (EVs).
- These EVs, similar to exosomes, contain proteins and RNAs and can bind specific ligands like cholera toxin B chain (CTB).
- Previous studies indicated CTB-binding EVs originate from endosomes and carry exosome markers.
Purpose of the Study:
- To investigate the heterogeneity of extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs).
- To differentiate and characterize MSC-derived EVs based on their binding affinities to specific lipid-binding ligands.
- To explore the distinct cargo, biogenesis, and potential functions of different EV subtypes.
Main Methods:
- Utilized Annexin V (AV) and Shiga toxin B subunit (ST) as ligands to identify and isolate distinct EV populations from MSCs, alongside CTB.
- Analyzed the proteomic and RNA content of these differentially isolated EV subsets.
- Investigated the subcellular localization of ligand-binding activities within MSCs.
Main Results:
- Identified at least three distinct EV types from MSCs based on binding to CTB, AV, and ST ligands.
- AV-binding EVs showed low exosome-associated proteins and distinct protein cargo compared to apoptotic bodies.
- ST-binding EVs were unique in carrying RNA and EDA-containing fibronectin, with ST-binding localized to the nucleus.
Conclusions:
- Mesenchymal stem cells secrete a heterogeneous population of extracellular vesicles (EVs).
- EVs can be selectively isolated using ligands targeting specific membrane lipids like GM1 ganglioside, phosphatidylserine, and globotriaosylceramide.
- Differential isolation based on ligand affinity reveals distinct EV subtypes with unique cargo, subcellular origins, and likely divergent biogenesis pathways and functions.
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