**1. Introduction**

Extracellular vesicles (EVs) are cell-derived membranous structures released by a multitude of cell types into the extracellular environment, from where they can enter body fluids and reach distant tissues, releasing their content [1]. Considered an essential pathway for intercellular communication, EVs are non-traditional lipid membrane-enclosed structures, with nanometric sizes [2]. Many studies have shown that EVs are produced by both prokaryotes and eukaryotes, indicating a persistent evolution of their signaling mechanism during a time, giving EVs an increasingly important role in the future [3, 4]. In general, EVs from the human blood are derived from platelets, but they can also be released from leukocytes, erythrocytes, endothelial cells, smooth muscle cells, and even cancer cells [5, 6].

Internal (platelet activation, pH variations, hypoxia, etc.) and external (irradiation, injury, etc.) factors can stimulate cells to produce EVs, that are secreted in lacrimal fluid, breast milk, broncho-alveolar lavage fluid, blood, ascites, urine, faces, etc. [3, 7, 8].

The content of EVs can vary to a great extent (lipids, proteins, nucleic acid species) and depends on the cell of origin [4, 6].

Their main function is represented by intercellular communication [2]. EVs can influence a variety of biological processes, transferring functional molecules (mRNA, microRNAs, and proteins) between cells [6, 9]. Their content is shuttled between cells, making EVs essential for a multitude of physiological, but also pathological processes (**Figure 1**). The various substances contained in the EVs can be taken up by other cells, both from the proximity of the cells of origin, but also from distant locations where they are transported by biofluids, inducing various phenotypic responses [10]. Apparently, this uptake is pH-dependent and can be of significance, especially in the tumor microenvironment [7].

EVs can also be considered as a possible source of biomarkers for early disease diagnosis [6, 11]. The implication of EVs in several diseases, including cancer, infectious diseases, neurodegenerative diseases, and blood diseases amplified the research interest, aiming to discover new possible therapeutic targets. EVs content can provide important leads about the type and stage of cancer, while during oncological treatment, the composition of EVs can change, which can be beneficial for therapeutic evaluation [5, 9, 12–14].

#### **Figure 1.**

*EVs, produced by different cell types, can be taken up by a recipient cell via phagocytosis, endocytosis, or membrane fusion. Thus, they can determine some biological effects. Oncosomes, a particular type of EVs produced by cancer cells, can stimulate the proliferation and invasiveness of cancer cells and tumor angiogenesis. They can also decrease antitumor immune response. Created with BioRender.com (last accessed on October 26, 2021).*

*Extracellular Vesicles as Intercellular Communication Vehicles in Regenerative Medicine DOI: http://dx.doi.org/10.5772/intechopen.101530*

EVs have various physiological and pathological roles. Current evidence points out their involvement in embryonic development, regenerative medicine (tissue regeneration), immunity modulation, angiogenesis, stress response, senescence, cell proliferation and differentiation, the capture of dissipated cancerous cells [4, 15–17].

Moreover, EVs can be regarded as therapeutic solutions and can act like possible alternatives to stem cell (SC) therapy [4].

Their role was and will continue to be exploited until reaching its maximum. Nowadays, EVs are also regarded as potential drug delivery and gene transport devices [18, 19].

Shortly, EVs are common vehicles between different cell types. Nowadays, their importance has attracted considerable scientific attraction due to their involvement in disease pathogenesis, different therapies, and also in many translational pathways. Extracellular vesicles are certainly a breakthrough in the regenerative medicine field, their involvement in many processes such as apoptosis, cell proliferation, differentiation, migration, angiogenesis, oxidative stress, aging, and inflammation being recently described. Lately, extracellular vesicles were also pointed out as important vehicles for multiple therapies due to their multifaceted roles.

The current chapter will summarize the most up-to-date knowledge about the role of EVs in regenerative medicine and will discuss the effects that EVs may have on tissue regeneration, a phenomenon that was initially focused only on cell therapies or tissue engineering. It will also approach the EVs' significance and crucial role in mediating cell-to-cell communication, especially their relationship with SCs and their biodisponibility in damaged tissue.
