**2. Study of EVs**

EVs can be released and interact with the target cell through different mechanisms. Currently, there are several databases that serve as resource for EVs research: Vesiclepedia [6, 7], EVpedia [8–10], ExoCarta [11–14], and EVmiRNA [15]. These databases include data from different organisms, type of vesicle, and content type (protein, mRNA, miRNA, and lipid). The composition of each kind of EV derives from the cell and purpose of the vesicle realized to the media. As such, these vesicles became an important marker for diseases, including cancer, infectious diseases, renal diseases, and diabetes [16–20]. In order to achieve this, EVs must be characterized and analyze their confidence to be candidates for those used by humans. The isolation and purification of different sets of EVs in a single cell is complicated.

Even though several studies isolate EVs from all kinds of fluids, including blood, urine, saliva, tears, semen, and cerebrospinal fluid, there is not a consensus to determine the best isolation technique to purify EVs. Several approximations have been published to isolate and analyze EVs from different sources [5, 21–23]. Differential centrifugation and ultracentrifugation are necessary steps at the beginning of the process to avoid sample contamination with non-EVs contaminants that can confound the analysis (ex. cellular debris, protein aggregates or lipoproteins). After the centrifugation steps, there are several techniques that can be used to isolate and analyze the EVs [24, 25]. Several common techniques are listed below:

**5**

*Introductory Chapter: An Overview to the Extracellular Vesicles*

The methods summarized above are the most common. However, there are more

variations of these methods used to purify EVs. All the methods have different advantages and disadvantages. Because of the diversity of the EVs, there is not a unique method to purify them. The selection of the method and the adaptation to the particular scenario is vital for the success of the isolation. After the EVs isolation, several procedures can be performed to characterize, quantify, and validate the correct purification of these organelles [5, 26–30]. The most common methods

*DOI: http://dx.doi.org/10.5772/intechopen.90820*

• Size exclusion chromatography

• Immunological separation

• Microfluidic chip

• Commercial precipitation kits

• Transmission electron microscopy (TEM)

• Atomic force microscopy (AFM)

• Dynamic light scattering (DLS)

• Single-particle tracking (SPT)

• Nanoparticle tracking analysis (NTA)

• Protein identification by mass spectrometry (MS)

**3. The role of the extracellular vesicles in human health**

Extracellular vesicles are released by many different cell types and organisms. The role of the EVs is mediated by the signals transmitted through them by the protein, lipids, and nucleic acids that are part of the EVs cargo. The release of the EVs to the environment allows the emitting cell to send messages to sites close or even far from the origin. These vesicles are able to transport biological information through

• Filtration

are listed below:

• Western blot

• Flow cytometry

• *In vitro* functional analyses

• *In vivo* functional analyses

• Lipidomic analysis

• RNA analysis

• ELISA


*Introductory Chapter: An Overview to the Extracellular Vesicles DOI: http://dx.doi.org/10.5772/intechopen.90820*


*Extracellular Vesicles and Their Importance in Human Health*

**4**

• Differential ultracentrifugation

• Density gradient ultracentrifugation

**2. Study of EVs**

**Figure 1.**

EVs can be released and interact with the target cell through different mechanisms. Currently, there are several databases that serve as resource for EVs research: Vesiclepedia [6, 7], EVpedia [8–10], ExoCarta [11–14], and EVmiRNA [15]. These databases include data from different organisms, type of vesicle, and content type (protein, mRNA, miRNA, and lipid). The composition of each kind of EV derives from the cell and purpose of the vesicle realized to the media. As such, these vesicles became an important marker for diseases, including cancer, infectious diseases, renal diseases, and diabetes [16–20]. In order to achieve this, EVs must be characterized and analyze their confidence to be candidates for those used by humans. The isolation and purification of different sets of EVs in a single cell is complicated. Even though several studies isolate EVs from all kinds of fluids, including blood, urine, saliva, tears, semen, and cerebrospinal fluid, there is not a consensus to determine the best isolation technique to purify EVs. Several approximations have been published to isolate and analyze EVs from different sources [5, 21–23]. Differential centrifugation and ultracentrifugation are necessary steps at the beginning of the process to avoid sample contamination with non-EVs contaminants that can confound the analysis (ex. cellular debris, protein aggregates or lipoproteins). After the centrifugation steps, there are several techniques that can be used to isolate and analyze the EVs [24, 25]. Several common techniques are listed below:

*Evolution of the number of papers published in PubMed over the past 21 years (1997–2018).*


The methods summarized above are the most common. However, there are more variations of these methods used to purify EVs. All the methods have different advantages and disadvantages. Because of the diversity of the EVs, there is not a unique method to purify them. The selection of the method and the adaptation to the particular scenario is vital for the success of the isolation. After the EVs isolation, several procedures can be performed to characterize, quantify, and validate the correct purification of these organelles [5, 26–30]. The most common methods are listed below:

