Extracellular Vesicles as Biomarkers of Graft-versus-Host-disease after Allogeneic Stem Cell Transplantation

Morbidity and mortality associated to Graft-Versus-Host Disease (GVHD) still represent a major concern of allografting (allo-HSCT). The identification of reliable, non-invasive, and predictive biomarkers for aGVHD could have a significant clinical impact. Recently, we investigated extracellular vesicles (EVs) and their cargo (miRNAs) as potential biomarkers of Acute GVHD in two pilot studies, with a limited cohort (41 and 32 patients, respectively). In the present study, we characterized EVs antigenic profile and miRNA cargo in a larger cohort of patients undergoing allo-HSCT to futher analyse this potential association. Serum samples were prospectively collected at given timepoints post allo-HSCT from 85 consecutive patients. EVs were extracted by a precipitative method and characterized by flow-cytometry with a 14 antibodies panel. Six miRNAs (miR100, miR194, miR155, miR146, miR29 and miR153) were extracted from EVs and quantified by qRT-PCR. Acute GVHD risk was evaluated by logistic and Cox regression models for each marker. Overall, we confirmed that the risk of developing aGvHD was associated with increased CD146 expression, as well as with miR100 and miR155 upregulation. Furthermore, our biomarker performance analyses suggest that the combination of EVs biomarkers could ameliorate the diagnostic performance of acute GVHD identifying patients with incipient and severe aGVHD. Indeed, despite the cellular origin of serum-derived EVs should be better clarified, our data demonstrated that EVs express markers related to injured endothelium and T cell activation, both essential events in aGVHD pathogenesis. This could have a significant clinical impact allowing better monitoring, early therapy and consequent reduced GVHD-related toxicities and mortality.