Overcoming Challenges in Exosome Research

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Emma Mason is the founder and director of Cambridge Technical Content Ltd, based in the U.K. Since graduating with a bachelor’s degree in biology from the University of Kent at Canterbury in 2000, she has gained extensive experience developing and running immunoassays within companies including Millennium Pharmaceuticals, AstraZeneca and Cellzome. She now produces a wide range of scientific content, including regular features for Biocompare.

July 24, 2025

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The field of exosome biology is evolving rapidly, aided by the development of innovative tools for exosome isolation and characterization. This article explores common challenges for exosome research before focusing on some of the products available to address these problems.

What are exosomes?

Exosomes are nanosized, membrane-bound particles secreted by cells into the extracellular space. They are distinguished from other types of extracellular vesicles (EVs), such as microvesicles and apoptotic bodies, by their endosomal route of origin, whereby the cell membrane invaginates to internalize various biomolecules from the surrounding milieu.^1,2 Because exosomes play a pivotal role in intracellular communication by mediating biomolecular transfer, they are being investigated for their potential utility in a broad range of diagnostic and therapeutic applications. For example, glypican-1⁺ exosomes hold promise as a biomarker for early pancreatic cancer, stem cell-derived exosomes are being studied for skin repair, and engineered exosomes are being developed for therapeutic delivery.^3-5

Limitations of established methods for exosome isolation

The small size, low abundance, and fragility of exosomes can make isolating them challenging. According to Eric Vincent, Ph.D., Sr. Product Manager at Promega Corporation, plasma-derived exosomes may be harvested by several broad routes, each balancing throughput, purity, and clinical practicality. “Differential or density-gradient ultracentrifugation remains a benchmark but demands hours of spin time and user intervention,” he says. “Size-exclusion and ultrafiltration columns offer gentler handling and modest equipment costs, yet often sacrifice yield and may co-isolate proteins. Rapid polyethylene-glycol precipitation delivers milliliter-scale throughput, but protein carryover can mask low-abundance biomarkers. And immunoaffinity capture methods targeting EV-specific markers typically use only one or two antigens, which ultimately will not select for all EVs in a biological system.”

Other common challenges for exosome research

“Besides isolation issues, another key challenge in EV research is the lack of standardization in vesicle validation,” reports Poppy Nathan, Ph.D., Scientific Marketing Specialist at Proteintech Group. This is being addressed by the International Society for Extracellular Vesicles (ISEV), which published an updated version of its Minimal Information for Studies of Extracellular Vesicles in 2023 (MISEV2023).⁶ “Proteintech’s antibody kits for exosome validation and characterization offer a comprehensive panel that aligns with the MISEV2023 guidelines, which recommend using multiple markers for accurate exosome identification,” says Nathan.

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For researchers studying the RNA cargo present in exosomes, obtaining enough material can be problematic. MicroRNAs (miRNAs)—the small, non-coding nucleotides that regulate gene expression post-transcriptionally—are an especially challenging sample type due to their low abundance. “Exosomal miRNAs have attracted great attention as biomarkers of cancer and other diseases,” reports Pedro Echave, Ph.D., Senior Manager, Global Business Segment at Revvity. “However, the exosomal miRNA content can be as little as 1 miRNA molecule per 100 exosomes, presenting significant issues for miRNA library preparation.”

Tools and technologies for studying exosomes

For researchers to fully leverage the diagnostic and therapeutic potential of exosomes, it has been necessary to develop novel tools and technologies for exosome isolation and characterization. The following are some of the available options:

• MACS^® EV Isolation Kits—Miltenyi Biotec

MACS EV Isolation Kits use MACS MicroBeads coupled to tetraspanin antibodies (CD9, CD63, CD81, or a combination of all three) to capture exosomes from biofluids. “Following a 1 hour incubation, the bead-bound exosomes are applied to a magnetic column, washed, and eluted,” explains Stefan Wild, Ph.D., Manager R&D at Miltenyi Biotec. “Compared to traditional EV isolation methods based on physical parameters like size and density, this approach is both gentler and faster.”

• MACSPlex^® EV Kits for characterizing EV populations—Miltenyi Biotec

MACSPlex EV Kits comprise a cocktail of fluorescently labeled MACSPlex bead populations, each coated with a specific antibody for one of 37 different EV surface epitopes (plus two isotype controls). After incubation with the sample, a detection cocktail containing CD9, CD63, and CD81-specific APC-conjugated antibodies is added and the resulting complexes are analyzed by flow cytometry.⁷ “MACSPlex EV Kits are available for immuno-oncology, neurobiology, and mesenchymal stem cell applications, where they provide a quick and easy method for profiling EV populations,” says Wild.

• Highly cited antibodies against exosome markers—Proteintech Group

Proteintech has developed an extensive portfolio of antibodies for exosome validation and characterization. This includes antibodies against the most widely used exosome markers, CD9, CD63, and CD81, as well as antibodies targeting multivesicular body-associated proteins (Alix, Tsg101), molecular chaperones (HSP70, HSP90), phospholipid-binding protein (Annexin V), and the exosome-associated epithelial marker (EpCAM). “We also offer Exosome Essentials and Exosome Expanded Antibody Kits, which each contain a panel of antibodies for studying exosomes, along with a cis-Golgi marker, GOLGA2/GM130, which serves as a reliable negative control,” says Nathan.

Notably, Proteintech’s antibodies against exosome markers are highly cited. For example, a recent Cell Research publication reports the use of Proteintech antibodies targeting CD63, TSG101, and CD9 to validate the exosome-mediated delivery of small interfering RNAs (siRNAs) in vivo.⁸ “This study demonstrated how liver cells can be engineered to package siRNAs into exosomes for systemic or tissue-specific gene silencing, highlighting the importance of reliable exosome markers in therapeutic development,” comments Nathan.

• NEXTFLEX^® Small RNA-Seq Kit v4—Revvity

The NEXTFLEX Small RNA-Seq Kit v4 provides a completely gel-free small RNA library preparation solution for Illumina and Element Biosciences sequencing platforms. Additionally, the protocol is fully automated on the Sciclone^® G3 NGS/NGSx and Zephyr^® G3 NGS workstations. “Libraries prepared with this kit have been shown to repeatedly produce high rates of miRNA mapping and unique miRNAs when working with challenging samples such as biofluids and purified exosomes,” says Echave. “Importantly, the kit minimizes adapter ligation bias and reduces adapter dimer formation, enabling high-quality results in as little as six hours.”

Recent reports citing the NEXTFLEX Small RNA-Seq Kit v4 for exosomal profiling include a study published earlier this year, which identified an EV-derived miRNA signature for septic shock in postsurgical patients.⁹

• Integrated exosome immunocapture and high-quality miRNA extraction—Promega

To streamline workflows involving both exosome isolation and miRNA extraction, Promega has united two magnetic particle technologies—INOVIQ EXO-NET’s immunoaffinity capture and its own Maxwell nucleic acid extraction chemistry. “Our workflow isolates intact EVs and their RNA cargo in a fully automated sequence without centrifugation, columns, or extensive manual processes,” reports Vincent. Specifically, EXO-NET capture (15 minutes) uses a 3D matrix of 10 antibodies covalently linked around a 40–50 nm paramagnetic core to bind a broad range of EVs directly from biological fluids. The automated Maxwell purification system (25–60 minutes, 16 or 48 samples/run) then shuttles the particles through chaotropic lysis, binding, ethanol washes and low-salt elution, yielding inhibitor-free total RNA or miRNA. “These two technologies, used together, enable researchers to isolate high-quality RNA from exosomes and other EVs that can be used in downstream assays such as RT-qPCR or NGS,” says Vincent.

• ViroCheck NanoParticle Reference Kit—Thermo Fisher Scientific

The ViroCheck NanoParticle Reference Kit from Thermo Fisher Scientific is designed for calibrating fluorescence during flow cytometric analysis of submicron particles, such as EVs. It includes 100 nm, 200 nm, and 500 nm particles with NIST-standardized ERF values across 15 filter set channels and serves to improve experimental precision and consistency. “Using this kit standardizes flow cytometry data, enabling quantitative and comparable exosome characterization across different instruments and labs, which is crucial for advancing exosome research,” says Daniel Applegate, Ph.D., Product Manager Flow Reagents.

• Total Exosome RNA & Protein Isolation Kit—Thermo Fisher Scientific

Thermo Fisher Scientific’s Total Exosome RNA & Protein Isolation Kit allows for the simultaneous recovery of small RNA species, including miRNAs, along with native protein content from exosome samples extracted from biofluids. One portion of the sample is subjected to organic extraction, followed by immobilization of RNA on glass-fiber filters, while the other is used directly for applications such as western blotting. “This approach provides ultra-pure RNA in just 30–60 minutes,” notes Rhonda Newman, Ph.D., Sr. Director, Sample Prep R&D. “The scalable, user-friendly method preserves exosome cargo integrity for downstream multi-omics applications.”