Research progress on exosomes derived from mesenchymal stem cells in hematological malignancies

Mesenchymal stem cell-derived exosomes for managing graft-versus-host disease: An updated view

Graft-versus-host disease (GvHD) is the most common complication after stem cell transplantation, and also it is one of the primary limiting factors for the use of hematopoietic stem cell transplantation (HSCT) in the treatment of hematologic cancers. GvHD, a systemic inflammatory disease, is caused by donor T cells recognizing the recipient's foreign antigens. In addition, an immune dysregulation, caused by autoreactive immune cells, complicates potent inflammatory process following HSCT. While there is no one approved treatment method for GvHD, corticosteroids are the most common first-line treatment. Exosomes are biological vesicles between 30 and 120 nm in diameter, which carry various biologically active molecules. They are known to play a key role in the paracrine effect of mesenchymal stem cells with therapeutic and tissue repair effects, including an immunosuppressive potential. Exosomes are unable to replicate themselves but because of their small size and fluid-like structure, they can pass through physiological barriers. Exosome are relatively easy to prepare and they can be quickly sterilized by a filtration process. Administration of exosomes, derived from mesenchymal stem cells, effectively reduced GvHD symptoms and significantly increased HSCT recipients' survival. Mesenchymal stem cell-derived exosome therapy reduced clinical symptoms of GvHD in patients after HSCT. Studies in patients with GvHD described that that mesenchymal stem cell-derived exosomes inhibited the release of IFN-γ and TNF-α by activated natural killer (NK cells), thereby reducing the lethal function of NK cells and inflammatory responses. Current review provides a comprehensive overview about the use of mesenchymal stem cells and their derived exosomes for the treatment of GvHD.

Research advances in the understanding of how exosomes regulate ferroptosis in cancer

Exosomes are extracellular vesicles that can release different bioactive substances to affect tumor cells and cell death pathways. As an important mediator of cell communication, exosomes participate in the occurrence and development of a variety of diseases. Ferroptosis, one of the newly defined forms of regulated cell death, is characterized by massive accumulation of iron ions and lipid peroxidation. An increasing number of studies have shown that ferroptosis plays an important role in malignant tumors. Moreover, exosomes have been recognized for their potential in cancer therapy based on ferroptosis. To further describe how could exosomes regulate ferroptosis in cancer and provide better understanding of the mechanisms involved, this paper reviews the definition as well as the underlying molecular mechanisms of ferroptosis, including iron metabolism, amino acid metabolism, lipid metabolism and so on. Then, we illustrated how could exosomes regulate the ferroptosis pathway and suggested their promising potential as a novel tumor therapy for cancer patients. Finally, we described the perspectives of ferroptosis by exosomes in tumor treatment. Therefore, exosomes have the potential to regulate ferroptosis in clinical cancer treatment.

Nucleic acids and proteins carried by exosomes from various sources: Potential role in liver diseases

Exosomes are extracellular membrane-encapsulated vesicles that are released into the extracellular space or biological fluids by many cell types through exocytosis. As a newly identified form of intercellular signal communication, exosomes mediate various pathological and physiological processes by exchanging various active substances between cells. The incidence and mortality of liver diseases is increasing worldwide. Therefore, we reviewed recent studies evaluating the role of exosomes from various sources in the diagnosis and treatment of liver diseases.

Small-sized extracellular vesicles (EVs) derived from acute myeloid leukemia bone marrow mesenchymal stem cells transfer miR-26a-5p to promote acute myeloid leukemia cell proliferation, migration, and invasion

Bone marrow mesenchymal stem cells (BMSCs) in acute myeloid leukemia (AML) microenvironment undergo modification that includes expression of contents in the small-sized extracellular vesicles (EVs) they secrete. This study aims to investigate whether small-sized EVs from BMSCs of AML patients regulate AML progression by modifying the expression of miR-26a-5p. Small-sized EVs from BMSCs of AML patients (AML-BMSC-EVs) or healthy controls (HC-BMSC-EVs) were isolated by ultra-centrifugation and administered to AML cells (OCI/AML-2 and THP-1). Cell proliferation, migration, and invasion were evaluated by CCK-8 assay, Transwell migration and invasion assays, respectively. Compared with HC-BMSC-EVs, AML-BMSC-EVs contained higher expression of miR-26a-5p and promoted AML cell proliferation, migration, and invasion. Inhibition of miR-26a-5p expression in AML-BMSC-EVs could abrogate the promoting effects of AML-BMSC-EVs on AML cell proliferation, migration, and invasion. Furthermore, GSK3β was a direct target of miR-26a-5p. Moreover, AML-BMSC-EVs inhibited GSK3β expression and activated Wnt/β-catenin signaling in AML cells. Additionally, GSK3β overexpression in THP-1 cells counteracted the promoting effects of AML-BMSCs-EVs on THP-1 cell proliferation, migration, and invasion. AML-BMSC-EVs promoted AML progression by transferring miR-26a-5p to AML cells and subsequently activating the Wnt/β-catenin pathway.