Graft-Versus-Host Disease Amelioration by Human Bone Marrow Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles Is Associated with Peripheral Preservation of Naive T Cell Populations

Abstract

A substantial proportion of patients with acute graft-versus-host disease (aGVHD) respond to cell therapy with culture-expanded human bone marrow mesenchymal stromal/stem cells (BM-MSCs). However, the mechanisms by which these cells can ameliorate aGVHD-associated complications remain to be clarified. We show here that BM-MSC-derived extracellular vesicles (EVs) recapitulated the therapeutic effects of BM-MSCs against aGVHD. Systemic infusion of human BM-MSCderived EVs prolonged the survival of mice with aGVHD and reduced the pathologic damage in multiple GVHD-targeted organs. In EV-treated GVHD mice, CD41 and CD81 T cells were suppressed. Importantly, the ratio of CD62L-CD441 to CD62L 1 CD44-T cells was decreased, suggesting that BM-MSC-derived EVs suppressed the functional differentiation of T cells from a naive to an effector phenotype. BM-MSC-derived EVs also preserved CD4 1 CD25 1 Foxp31 regulatory T cell populations. In a culture of CD3/CD28-stimulated human peripheral blood mononuclear cells with BM-MSC-derived EVs, CD31 T cell activation was suppressed. However, these cells were not suppressed in cultures with EVs derived from normal human dermal fibroblasts (NHDFs). NHDF-derived EVs did not ameliorate the clinical or pathological characteristics of aGVHD in mice, suggesting an immunoregulatory function unique to BM-MSC-derived EVs. Microarray analysis of microRNAs in BM-MSCderived EVs versus NHDF-derived EVs showed upregulation of miR-125a-3p and downregulation of cell proliferative processes, as identified by Gene Ontology enrichment analysis. Collectively, our findings provide the first evidence that amelioration of aGVHD by therapeutic infusion of BM-MSCderived EVs is associated with the preservation of circulating naive T cells, possibly due to the unique microRNA profiles of BM-MSC-derived EVs. STEM CELLS 2018;36:434-445 SIGNIFICANCE STATEMENTCell therapy with human bone marrow mesenchymal stromal/stem cells (BM-MSCs) is clinically effective for patients with intractable acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation. This study revealed that BM-MSC-derived extracellular vesicles (EVs) recapitulated the therapeutic effects of BM-MSCs against aGVHD by inhibiting effector T cell induction and preserving peripheral naive T cells. Gene Ontology analysis of microRNAs differentially expressed in BM-MSC-derived EVs suggested that these microRNAs may downregulate cell proliferative processes. These findings suggest that BM-MSC-derived EVs mediate the anti-aGVHD effects of BM-MSCs, thereby raising the possibility of using EVs as a cell-free therapy for the treatment of aGVHD.

Immunoregulatory Effects of Stem Cell-Derived Extracellular Vesicles on Immune Cells

“…The immunoregulatory effects exerted by SC-EVs on activated T cells remain a widely debated topic. For instance, one study observed that the co-culture of SC-EVs with peripheral blood mononuclear cells (PBMCs) specifically suppressed the proliferation of T cells, whereas it did not affect that of B cells and NK cells (71). However, other studies have reported that SC-EVs inhibited the proliferation of NK cells and B cells, although its effect on the proliferation of T cells remains unclear (30,108).…”

“…It has been demonstrated that SC-EVs carry a variety of active molecules, such as TGF-β (10, 92), active CD73 protein (11,79), IDO protein (88), or miR-125a-3p (71). These molecules endow SC-EVs with the ability to inhibit T cell proliferation (11,71,88,92,98,112,116,117) and activation (71,76,77,97,98,112,116), and preserve the circulating naive T cells (71) ( Table 1).…”

Potential roles of extracellular vesicles in the pathophysiology, diagnosis, and treatment of autoimmune diseases

“…In the present work, MSC-EVs have been shown to possess immunomodulatory functions which promote B cell activation, induction of Breg and B cell proliferation was compared to that the whole MSCs [57]. Fujii et al, showed EVs derived from BM-NSCs have potential therapeutic effect on acute graft versus host disease (GVHD) and indicated the EVs probably inhibit the effector T cell induction and kept circulating naïve T cells [58]. However, EV usually does not treat as well as the cell itself, and its biological effects may be affected by the surrounding microenvironment [59].…”

“…The EVs isolated from patient serum contains three miRNAs (miR-423, miR-199, miR-93), which may be related to the incidence and severity of GVHD [68]; and the expression of CD146, CD31, and CD140-α on EVs surface, is also closely related to the onset of the disease [69]. Traditional MSCs therapy after replacement with EVs for GVHD also showed ideal results, suggesting that MSCs-derived EVs are potential for cell-free therapy for GVHD [58,70]. Kordelas L et al used MSCs-derived EVs instead of MSCs in the patient with GVHD, and the promising results were obtained.…”

Therapeutic Advances of Stem Cell-Derived Extracellular Vesicles in Regenerative Medicine

“…Preclinical studies have confirmed that SC-EVs can wield immunomodulatory effects in the treatment of various diseases by transporting noncoding RNAs, cytokines, and other immunomodulatory molecules. Fujii et al showed that human BMSC-EVs reduced the ratio of CD62L-CD44+/CS62+CD44-T cells in graft-versus-host diseased mice and prolonged their survival by transporting miR-125a-3p [76]. Li et al showed that hucMSC-EXs reduced inflammation in burned rats by inhibiting the expression of Toll-like receptor 4 in macrophages [77].…”