EN
Exosome Isolation and Characterization Methods: A Practical Guide
Exosomes are membrane-bound vesicles with a diameter of approximately 30–150 nm. They are widely present in body fluids such as blood, urine, saliva, cerebrospinal fluid, and peritoneal fluid, where they serve as messengers for intercellular material exchange and communication. Almost all cell types can release exosomes under physiological or pathological conditions, including cell activation, stress, and apoptosis.
With broad application potential, exosomes have become a major focus in life science research in recent years. Obtaining exosomes with high purity while preserving their biological activity is fundamental to downstream studies. So, what are the commonly used methods for exosome isolation and characterization?
Exosome Isolation Methods
| Method | Principle | Advantages | Limitations |
|---|---|---|---|
| 01. Ultracentrifugation | A mainstream method for exosome isolation. Based on exosome size, ultracentrifugation removes cells, large vesicles, and cellular debris, and then pellets exosomes. | Suitable for isolating exosomes from biological fluids and culture media. | Low extraction efficiency for viscous biological fluids such as plasma and serum. Requires an ultracentrifuge and multiple centrifugation steps, making the process time-consuming. Requires a relatively large sample volume. |
| 02. Density Gradient Centrifugation | Exosomes can be enriched in a sucrose density gradient solution using sucrose density gradient ultracentrifugation. | Enables separation of low-density exosomes from other vesicles, particles, and contaminants. | Highly sensitive to centrifugation time. Technically demanding, more complex than conventional ultracentrifugation, and associated with higher experimental costs. |
| 03. Ultrafiltration | Exosomes are isolated and extracted using membranes with different pore sizes. Ultrafiltration membranes are used to separate exosomes from proteins and other macromolecules. | Produces exosomes with relatively high purity. | Exosomes may adhere to the filtration membrane, which can cause membrane clogging or shorten membrane lifespan. In addition, because extra force is applied to push the liquid sample through the membrane, exosomes may become deformed or damaged. |
| 04. Immunoaffinity Isolation | This method isolates exosomes based on the expression of surface markers. Magnetic beads conjugated with specific antibodies are used to capture and separate exosomes. | Allows isolation of total exosomes or selected exosome subtypes. Can also be used for qualitative and quantitative analysis of exosomal proteins. Enables acquisition of exosomes with higher affinity and specificity. | Not suitable for large sample volumes. The isolated vesicles may lose functional activity. |
| 05. Size-Based Filtration/Sieving Isolation | This technique separates exosomes through membrane sieving and filtration driven by pressure or electrophoresis. | Relatively short isolation time and high-purity exosomes. | Low recovery rate of isolated exosomes. |
| 06. Size-Exclusion Chromatography | Solutes are separated based on the relationship between the pore size of gel voids and the molecular size of the sample. Size-exclusion columns contain resin with nanopores of different diameters; larger vesicles can pass through rapidly and elute in the void volume. | Helps prevent loss of exosome biological function and better preserves the native state of exosomes. | Not suitable for processing large sample volumes. |
A variety of methods are currently available for exosome extraction and isolation, and commercial exosome isolation kits have also been developed. However, there is still no perfect isolation method. Researchers should select the most appropriate method based on sample source and downstream analysis requirements. For example, one study isolated exosomes from mouse serum using ultracentrifugation and density gradient centrifugation. The results showed that ultracentrifugation performed better than density gradient centrifugation in terms of purity and application potential; the isolated exosomes showed a more uniform distribution, clearer structure, and less aggregation [1].
Exosome Characterization Methods
Mainstream exosome characterization typically relies on three types of validation: transmission electron microscopy, particle size analysis, and protein marker detection.
| Method | Purpose and Key Features |
|---|---|
| 01. Transmission Electron Microscopy (TEM) | TEM enables simple and direct observation of exosome morphology, including shape, size, and partial structural features. It can be used for a preliminary assessment of whether exosome isolation was successful and whether the obtained exosomes are of acceptable quality. Under electron microscopy, exosomes typically appear as cup-shaped or saucer-like round or oval vesicles. |
| 02. Nanoparticle Tracking Analysis (NTA) | NTA can be used to detect the particle size distribution and particle concentration of exosomes. |
| 03. Protein Marker Detection by Western Blotting (WB) | Exosomal marker proteins are detected to characterize exosomes at the protein level. |
OriCell Exosome Research Services
Based on extensive experience in stem cell research projects and strong platform capabilities, Cyagen OriCell provides cell and reagent products for exosome research, as well as services for exosome isolation, characterization, cargo detection, and validation.
1. Primary Stem Cells
A broad range of mesenchymal stem cells, neural stem cells, and embryonic stem cells.
2. Exosome-Depleted Media
Suitable for bone marrow, adipose, umbilical cord, cord blood, and dental pulp mesenchymal stem cells.
3. Isolation and Characterization Services
Standard services are available, and customized services can also be provided according to your research needs.
Cyagen OriCell's offerings are cited in over 10,000 publications, with a cumulative impact factor exceeding 90,000 and more than 160,000 citations, and the team has supported more than 3,000 research groups. Products are used by tens of thousands of customers across dozens of countries and regions.
References
- Qiu Shantong, Zhang Hao, Shen Yali, et al. Comparison of Different Extraction Methods for Exosomes from Mouse Serum [J]. Experimental Research, 2021.
- Exosomes: Isolation and Characterization Methods and Specific Markers. DOI: https://doi.org/10.13070/mm.en.5.1450
