Microvesicles vs exosomes: why differentiate them into biomarkers?

In the field of extracellular vesicle (EV) biology, exosomes have become prominent players for their role as biomarker carriers in cancer, neurodegenerative diseases or advanced therapies. However, a nearby – and often overlooked – player also deserves attention: microvesicles.

In this post we address the key differences between exosomes and microvesicles, and explain why distinguishing them correctly makes a difference in the development of clinically valid biomarkers.

What are exosomes and microvesicles?

Both are extracellular vesicles, but their origin and characteristics make them unique:

-Exosomes: they geenran inside endosomes and are released upon fusion with the plasma membrane, They are between 30-150 nm in size.

-Microvesicles (also called ectosomes): Sprout directly from the plasma membrane. Their size varies between 100-1000 nm.

These differences are not merely morphological: they affect their protein content, lipid profile, biological function and, most importantly, their value as biomarker vehicles.

Why is it crucial to differentiate them?

1. Accuracy in biomarker development-Numerous studies have shown that mixing populations of EVs can lead to confusing or non-reproducible results. A biomarker present in exosomes, for example, might be absent in microvesicles, or viceversa. In the development of diagnostic kits or detection panels, this can lead to false positives or negatives, reducing their clinical validity.
2. Customized isolation strategies- Each type of EV requires specific isolation strategies. Ultracentrifugation-based methods, for example, tend to co-enrich multiple vesicle subtypes. Thus, the use of specific antibodies or optimized reagents is critical to characterize pure populations. At Immunostep we offer solutions for specific exosome detection and analysis by flow cytometry, enabling higher resolution and reproducibility.
3. Therapeutic and regulatory applications- The rise of extracellular vesicle-based therapeutics raises regulatory questions. How do you control a heterogeneous product? Traceability and purity of EVs will be a key requirement, especially if we aim for clinical use

How can you differentiate them in your laboratory?

The first step is to clearly define your objective: are you looking for exosomal markers? Do you want to validate a population of EVs in a complex fluid?

In that context, we recommend:

• Use of specific antibodies against tetraspanin markers such as CD63, CD9 or CD81 (exosomes).
• Combination with techniques such as nanoparticle tracking analysis (NTA) or sensitive flow cytometry.
• Cross-validation with well-characterized standards, such as those you can find in our product line for detection and analysis of extracellular vesicles.

Conclusion

In biomedical research, details make the difference. Treating exosomes and microvesicles as equivalent may seem practical, but it compromises the scientific and clinical validity of the results.

Differentiating between the two types of vesicles is not just a technical issue: it is an essential step towards precision medicine. At Immunostep, we work to offer solutions that allow you to address this complexity with rigor and reliability.