Experimental evidence and preliminary clinical studies have demonstrated that human mesenchymal stem cells (MSCs) display important immune modulatory function of potential relevant interest in the setting of allogeneic hematopoietic stem cell (HSC) transplantation. Effectiveness of MSCs in controlling severe GVHD seems to be related to the immune-regulatory role they play in suppressing alloantigen-specific T-cell activation. Aim of the present study was to extend the analysis of the mechanisms responsible for the immune regulatory effect of interaction between MSCs and alloantigen-specific immune response elicited in vitro in primary and in secondary mixed lymphocyte culture (MLC). At difference with most previously reported studies, we decided to employ non-irradiated MSCs, reasoning that irradiation might impair, beside the proliferative capacity, also the differentiation capability of MSCs and, consequently, alter their interaction pattern with lymphocyte subsets. MSC were added to primary MLC at different doses (MLC-responder-PBMC:MSC ratios = 1:1 and 10:1). Dendritic cell (DC) differentiation, lymphocyte proliferation, alloantigen-specific cytotoxic activity and differentiation of CD4+ T-cell subsets expressing CD25 and/or CTLA4 antigens were assessed in primary and secondary MLC, comparing the effect observed using third-party MSCs with that obtained employing autologous to the MLC-responder (autologous) MSCs. Results demonstrated that human MSCs: (1) strongly inhibit alloantigen-induced DC1 differentiation; (2) down-regulate, in a dose-dependent manner, alloantigen-induced lymphocyte expansion, especially that of CD8+ T cells and of NK lymphocytes; (3) favor the differentiation of CD4+ T cells co-expressing CD25 and/or CTLA4, a phenotype associated with regulatory/suppressive function of immune response; (4) cause a dose-dependent reduction of alloantigen-specific cytotoxic capacity mediated by either cytotoxic T lymphocytes or NK cells; (5) exert more effective suppressive activity on MLC-induced T-cell activation when they are allogeneic rather than autologous with respect to responder cells. In particular, higher percentages of CD4+ and of CD4+CD25+ T cells co-expressing CTLA4+ were detected when third-party, rather than autologous, MSCs were added to MLC. These data suggest that T-cell recognition of alloantigens expressed by MSCs may further facilitate the preferential differentiation of activated CD4+ T cells expressing CTLA4, a glycoprotein, known to deliver an inhibitory signal to T cells and to mediate apoptosis of previously activated T lymphocytes. Several studies previously demonstrated that MSCs exert inhibitory effect on lymphocyte activation through the release of soluble factors. Our data suggest that the preferential differentiation of CD4+CD25+ regulatory T-cell subsets may be favored by other mechanisms of MSC-mediated inhibition of alloantigen-induced effector cell activation and expansion, and, in turn, these CD4+CD25+ cells contribute to propagate and extend suppressor activity. Altogether, our results provide immunological support to the use of MSCs for prevention of immune complications related to both HSC and solid organ transplantation and to the theory that MSCs are “universal” suppressors of immune reactivity.

PurposeIncreasing the number of hematopoietic stem and progenitor cells within an umbilical cord blood (UCB) graft shortens the time to hematopoietic recovery after UCB transplantation. In this study, we assessed the safety and efficacy of a UCB graft that was expanded ex vivo in the presence of nicotinamide and transplanted after myeloablative conditioning as a stand-alone hematopoietic stem-cell graft.MethodsThirty-six patients with hematologic malignancies underwent transplantation at 11 sites.ResultsThe cumulative incidence of neutrophil engraftment at day 42 was 94%. Two patients experienced secondary graft failure attributable to viral infections. Hematopoietic recovery was compared with that observed in recipients of standard UCB transplantation as reported to the Center for International Blood and Marrow Transplant Research (n = 146). The median time to neutrophil recovery was 11.5 days (95% CI, 9 to 14 days) for recipients of nicotinamide-expanded UCB and 21 days (95% CI, 20 to 23 days) for the comparator (P < .001). The median time to platelet recovery was 34 days (95% CI, 32 to 42 days) and 46 days (95% CI, 42 to 50 days) for the expanded and the comparator cohorts, respectively (P < .001). The cumulative incidence of grade 2 to 4 acute graft-versus-host disease (GVHD) at day 100 was 44%, and grade 3 and 4 acute GVHD at day 100 was 11%. The cumulative incidence at 2 years of all chronic GVHD was 40%, and moderate/severe chronic GVHD was 10%. The 2-year cumulative incidences of nonrelapse mortality and relapse were 24% and 33%, respectively. The 2-year probabilities of overall and disease-free survival were 51% and 43%, respectively.ConclusionUCB expanded ex vivo with nicotinamide shortens median neutrophil recovery by 9.5 days (95% CI, 7 to 12 days) and median platelet recovery by 12 days (95% CI, 3 to 16.5 days). This trial establishes feasibility, safety, and efficacy of an ex vivo expanded UCB unit as a stand-alone graft.

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Aging is a physiological process in which multifactorial processes determine a progressive decline. Several alterations contribute to the aging process, including telomere shortening, oxidative stress, deregulated autophagy and epigenetic modifications. In some cases, these alterations are so linked with the aging process that it is possible predict the age of a person on the basis of the modification of one specific pathway, as proposed by Horwath and his aging clock based on DNA methylation. Because the energy metabolism changes are involved in the aging process, in this work, we propose a new aging clock based on the modifications of glucose catabolism. The biochemical analyses were performed on mononuclear cells isolated from peripheral blood, obtained from a healthy population with an age between 5 and 106 years. In particular, we have evaluated the oxidative phosphorylation function and efficiency, the ATP/AMP ratio, the lactate dehydrogenase activity and the malondialdehyde content. Further, based on these biochemical markers, we developed a machine learning-based mathematical model able to predict the age of an individual with a mean absolute error of approximately 9.7 years. This mathematical model represents a new non-invasive tool to evaluate and define the age of individuals and could be used to evaluate the effects of drugs or other treatments on the early aging or the rejuvenation.