Current Molecular Medicine - Volume 22, Issue 2, 2022

The recent developments in the field of extracellular vesicles (EVs) point to their potential use for predicting and treating neurodegenerative diseases. This review focusses on the importance and latest advances in this field, especially with respect to Alzheimer’s disease (AD). Increasing evidence shows that the progression of amyloidbeta and tau brain pathology is correlated to the cognitive decline associated with AD. Lot of experimental data suggests the involvement of EVs with these processes, for instance EVs are known to circulate the misfolded proteins involved in AD. The currently available information on the role of EVs in neurodegenerative disorder especially in AD have also presented the knowledge gaps on which future research efforts should be focused.

Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into diverse cell lineages. MSC based therapy has become a widely experimented treatment strategy in regenerative medicine with promising outcomes. Recent reports suggest that much of the therapeutic effects of MSCs are mediated by their secretome that is expressed through extracellular vesicles (EVs). EVs are lipid bilayer bound components that carry cellular proteins, mRNA, lncRNAs, and other molecules in order to mediate intercellular communication and signaling. In fact, MSC-derived EVs have been observed to implement the same therapeutic effects as MSCs with minimal adverse effects and could be used as an alternative treatment method to MSC-based therapy. The regenerative activity of MSC-EVs has been observed in relation to multiple cell/tissue lineages using various animal models. However, further research and clinical trials are essential for the advancement of this novel treatment strategy. This review provides an insight into the available literature on applications of MSC-EVs in relation to angiogenesis, neurogenesis, hepatic and kidney regeneration, and wound healing.

Cell-based regenerative therapies involving stem or progenitor cells are considered as possible therapeutic modalities to treat non-communicable and degenerative diseases. Recently, regenerative outcomes of cell-based therapies have been linked to paracrine factors and extracellular vesicles [EVs] released by the transplanted cells rather than the transplanted cells themselves. EVs contain a cargo that includes microRNAs [miRNAs], mRNAs, as well as proteins. Their role in mediating intercellular communication has been acknowledged in several studies. However, the regenerative potential of the miRNAs, mRNAs, and proteins that are present in EVs is a matter of ongoing scientific debate. In this review, we discuss EVs as an alternative to stem cell-based therapy to treat some of the non-communicable and degenerative diseases. Moreover, we also propose that pre-treatment of the cells could help to produce EVs enriched with particular miRNAs, mRNAs, and/or proteins that could support the successful regeneration of a targeted organ

Extracellular vesicles (EVs), which are released by most of the cells, constitute a new system of cell-cell communication by transporting DNA, RNA, and proteins in various vesicles namely exosomes, apoptotic bodies, protein complexes, high-density lipid (HDL) microvesicles, among others. To ensure accurate regulation of somatic stem cell activity, EVs function as an independent metabolic unit mediating the metabolic homeostasis and pathophysiological of several diseases such as cardiovascular diseases, metabolic diseases, neurodegenerative diseases, immune diseases, and cancer. Whist examining the EV biomolecules cargos and their microenvironments that lead to epigenetic alteration of the cell in tissue regeneration, studies have gained further insights into the biogenesis of EVs and their potential roles in cell biology and pathogenicity. Due to their small size, non-virulence, flexibility, and ability to cross biological barriers, EVs have promising therapeutic potentials in various diseases. In this review, we describe EV’s mechanism of action in intercellular communication and transfer of biological information as well as some details about EVinduced epigenetic changes in recipient cells that cause phenotypic alteration during tissue regeneration. We also highlight some of the therapeutic potentials of EVs in organ-specific regeneration.

Liver fibrosis is one of the leading causes of cirrhotic liver disease, and the lack of therapies to treat fibrotic liver is a major concern. Liver fibrosis is mainly occurred by activation of hepatic stellate cells, and some stem cell therapies had previously reported for treatment. However, due to some problems with cell-based treatment, a safe therapeutic agent is vehemently sought by the researchers. Extracellular vesicles are cell-derived nanoparticles that are employed in several therapeutic approaches, including fibrosis, for their ability to transfer specific molecules in the target cells. In this review, the possibilities of extracellular vesicles to inactivate stellate cells are summarized and discussed. According to several studies, extracellular vesicles from different sources can either have beneficial or detrimental effects by regulating the activation of stellate cells. Therefore, targeting extracellular vesicles for maximizing or inhibiting their production is a potential approach for fibrotic liver treatment. Extracellular vesicles from different cells can also inactivate stellate cells by carrying out the paracrine effects of those cells, working as the agents. They are also implicated as a smart carrier of anti-fibrotic molecules when their respective parent cells are engineered to produce specific stellate cell-regulating substances. A number of studies showed stellate cell activation can be regulated by up/downregulation of specific proteins, and extracellular vesicle-based therapies can be an effective move to exploit these mechanisms. In conclusion, EVs are advantageous nano-carriers with the potential to treat fibrotic liver by inactivating activated stellate cells by various mechanisms.

Wound healing is an elaborated process, well-regulated via cell migration and proliferation. Although the physiological basics of wound healing have been thoroughly investigated and reported, much remains to be studied. Particularly, various studies have demonstrated the immunomodulatory roles of exosomes derived from plant cells, mammalian cells, and mesenchymal stem cells (MSCs) in the healing and repairing system. The paracrine and therapeutic effects of exosomes are mainly associated with the broad exosomal cargo content comprising growth factors, cytokines, enzymes, nucleic acids, proteins, and lipid signaling molecules. Nevertheless, the functional or mechanism pathway of exosomes with reference to overall exosomal cargo remains undetermined. To date, combinatorial analysis strategies employing Database for Annotation, Visualization, and Integrated Discovery (DAVID), STRING tools, Gene Ontology (GO), Kyoto Encyclopedia of Genes, Genomes (KEGG) pathway enrichment analysis, as well as Ingenuity Pathway Analysis (IPA) have been applied in elucidating network interaction and functional pathway of exosomes. In this review paper, the application of combinatorial analysis strategies is demonstrated to better understand the therapeutic potentials of exosomes in the wound healing process. In conclusion, functional modulation of exosomal cargo for specific biological treatment is achievable, and modelling of combinatorial analysis strategies will hopefully bridge the research gap and provide a paradigm shift to regenerative processes.