ExoBrite™ STORM CD9 Antibody

Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) are emerging as powerful, cell-free immunomodulatory therapies for inflammatory diseases such as COVID-19. However, because the mechanism is poorly understood, optimizing EV-based therapies remains challenging.

In a 2025 Springer Nature study, Infante et al. investigated how COVID-19 patient serum reshapes the transcriptome and paracrine activity of Wharton’s jelly–derived MSC stem cells (WJ-MSCs). WJ-MCSs exposed to serum from hospitalized COVID patients showed downregulation of NEAT1 and MALAT1, two pro-inflammatory two long noncoding RNAs (lncRNAs). Furthermore, the researchers found that EVs derived from the treated cells had enhanced immunosuppressive activity when administered to T-cells.

The researchers isolated EVs from WJ-MSC cells after NEAT1 and/or MALAT1 knockdown, and tested whether there was an effect on T-cell proliferation. A Western blot of EVs derived from control and lncRNA-knockdown MSCs were probed with ExoBrite™ 680/700 CD81 Western Antibody. ExoBrite™ 770/800 Calnexin Western Antibody was also used as an endoplasmic reticulum marker to assess cellular contamination.

EV enriched samples in control, NEAT1 knockdown, MALAT1 knockdown, and NEAT1/MALAT1-double knockdown were confirmed by bright CD81 detection and the absence of Calnexin. They found that the MALAT1 knockdown EVs were found to have an inhibitory effect on T-cell proliferation. These results illustrate the importance of EV characterization using tools like Biotium’s ExoBrite™ antibodies in translational EV research.

Isolation and characterization of EVs from various lncRNA knock-down WJ-MSCs. Western blot analysis using ExoBrite™ 680/700 CD81 and ExoBrite™ 770/800 Calnexin in EV and MSC lysates. Asterisk (*) indicates reduced conditions used in the MSCs lysate. Modified from Infante et. al. Reproduced under CC BY 4.0.

Learn more about Biotium’s many stains and antibodies for EV research, including ExoBrite™ CD9/CD63/CD81 Antibody Cocktails for flexible and bright multiplexing detection by flow cytometry. Biotium also offers ExoBrite™ stains for pan-EV labeling, optimized fluorescent conjugates of CTB, WGA, and Annexin V for EV detection, ExoBrite™ antibodies for STORM imaging, and more.

Full Citation:

Infante, A., Cabodevilla, L., Gener, B. et al. Modulation of NEAT1 and MALAT1 expression in WJ-MSCs by Covid-19 serum: a foundation for EVs-mediated therapy. Respir Res 26, 313 (2025). https://doi.org/10.1186/s12931-025-03394-4

While early studies of EVs attempted to use first-generation membrane dyes like DiI or PKH to stain EVs, more recently this class of dyes has been found to be largely unsuitable for EV staining due to their high degree of aggregation. Dye aggregation not only generates nonspecific particles that are indistinguishable from EVs in flow cytometry, but also results in poor EV labeling efficiency. Biotium developed the ExoBrite™  True EV Membrane Stains in response to our customers’ difficulties with using traditional membrane dyes to stain EVs. See our Literature Digest for more information.

We strongly recommend our ExoBrite™ Flow Antibody Conjugates for staining both purified or bead-bound EVs. The antibodies are validated and optimized to offer bright signal and low background. They are available against human or mouse CD9, CD63, and CD81 tetraspanin proteins.