Extracellular Vesicles and Exosomes: Insights From Exercise Science

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  FIGURE 1. Schematic representation of extracellular vesicles released by cells in response to exercise. Apoptotic bodies (∼>500 nm), microvesicles (∼100–1,000 nm) and exosomes (∼40–120 nm). (A) Exosome formation. Early endosomes form from the inward budding of the plasma membrane (PM) before maturing into late endosomes which contain multiple intraluminal vesicles (ILVs). With the presence of ILVs, the late endosome can also be characterized as a multivesicular body (MVB) (Sotelo and Porter, 1959; Akers et al., 2013). MVBs exist in different subpopulations (White et al., 2006) can either fuse with a lysosome for degradation, or fuse with the PM to release ILVs into the extracellular space as exosomes (Akers et al., 2013; Crenshaw et al., 2018). MVB development in an Endosomal Sorting Complex Required for Transport (ESCRT)-dependent or independent manner with tetraspanins (Hemler, 2005; Pols and Klumperman, 2009) or ceramides (Trajkovic et al., 2008) being involved. Rab GTPases (RABs) and soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) may also regulate the cargo sorting and transport of exosomes. (B) Exosome uptake in recipient cell. Following release,…

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  FIGURE 2. Schematic representation of the proposed origin, release, composition, and cargo of exosome-like vesicles (ELVs) following an exercise stimulus. Following either chronic training or a single bout of exercise, ELVs may be released from muscle or other cell populations and enter into the systemic circulation. Exercise-induced alterations in plasma concentration, exosome markers (e.g., ALIX, TSG101, tetraspanins, flotillin, and heat shock proteins) and cargo (e.g., miRNA, ‘myomiR’ abundance) have been observed. APC, antigen presenting cell; α-SGC, α-sarcoglycan; FABP, fatty-acid-binding proteins; WBC, white blood cells; including monocytes and lymphocytes.