Exosomes Derived from Human Primed Mesenchymal Stem Cells Induce Mitosis and Potentiate Growth Factor Secretion

Abstract

Mesenchymal stem cells (MSCs) facilitate functional recovery in numerous animal models of inflammatory and ischemic tissue-related diseases with a growing body of research suggesting that exosomes mediate many of these therapeutic effects. It remains unclear, however, which types of proteins are packaged into exosomes compared with the cells from which they are derived. In this study, using comprehensive proteomic analysis, we demonstrated that human primed MSCs secrete exosomes (pMEX) that are packaged with markedly higher fractions of specific protein subclasses compared with their cells of origin, indicating regulation of their contents. Notably, we found that pMEX are also packaged with substantially elevated levels of extracellular-associated proteins. Fibronectin was the most abundant protein detected, and data established that fibronectin mediates the mitogenic properties of pMEX. In addition, treatment of SHSY5Y cells with pMEX induced the secretion of growth factors known to possess mitogenic and neurotrophic properties. Taken together, our comprehensive analysis indicates that pMEX are packaged with specific protein subtypes, which may provide a molecular basis for their distinct functional properties.

Preclinical translation of exosomes derived from mesenchymal stem/stromal cells

“…Due to the potential for coisolation of residual FBS exosomes, as well as FBSderived protein aggregates, it may be advantageous to use serum-free isolation media to diminish the possibility of introducing bovine-derived artifacts. 7 However, the optimum media constituents required to manufacture MEX with maximum potency has yet to be determined, and may vary according to the target disease.…”

“…35,36 In addition, MEX are highly enriched for extracellular proteins. 7 Therefore, an increased focus on the proteins packaged into MEX is warranted. However, the critical and essential factors that are packaged into MEX that mediate their immunomodulatory and tissue healing properties have yet to be robustly characterized.…”

“…4 There are likely several reasons for such differences observed between MSC preclinical and clinical studies such as potency, consistency and scale-up manufacturing issues which have been reviewed elsewhere. 4,5 MSCs' therapeutic effects are generally thought to be mediated through the secretion of a variety of factors including canonical secretory proteins such as cytokines and growth factors, as well as exosomes [6][7][8][9][10] (Figure 1). MSCs act as a localized delivery system by secreting such factors, which then in turn affect the physiology of both adjacent and distant responder cells.…”

Dynamic Changes in Function and Proteomic Composition of Extracellular Vesicles from Hepatic Stellate Cells during Cellular Activation

“…In activated HSC, FN1-integrin α5β1 interactions are important for the regulation of cell adhesion, survival, cytoskeletal rearrangements or expression of matrix metalloproteases or collagen I [53][54][55][56][57], but this interaction may also underlie the binding of EVs to target HSC, the extent of which will be dependent on activation-associated changes in cellular integrin expression and EV FN1 levels. Importantly, EV FN1 may also directly participate in downstream pro-fibrogenic actions of HSC EVs in light of recent studies showing, firstly, that FN1 in cancer cell microvesicles mediates their ability to confer transformation characteristics on fibroblasts and epithelial cells [58] and, secondly, that exosomal FN1 mediates the mitogenic activity of exosomes from mesenchymal stem cells [59]. Such functions may also be conserved in EVs from hHSC, since we showed FN1 to be the most abundant component of EVs from LX-2 cells in these studies.…”

Immunoregulatory Potential of Exosomes Derived from Cancer Stem Cells

“…However, it is feasible that CSC secrete CSCEX, which possess similar immunosuppressive properties similar to TEX [85]. Numerous reports have established that exosomes derived from other stem cell source possess comparable properties as well [149][150][151][152].…”