Lee JY, et al. Blood Res. 2017 Sep;52(3):184-192. https://doi.org/10.5045/br.2017.52.3.184

Objective: Myeloid‐derived suppressor cells (MDSCs) facilitate tumor growth and development by suppressing T cell function; however, their role in acute myeloid leukemia (AML) remains unclear. Here, we investigated the immunosuppressive role and prognostic value of blasts with an MDSC‐like phenotype.Methods: CD11b⁺CD33⁺HLA‐DR⁻ MDSC‐like blasts from bone marrow mononuclear cells of patients with AML were analyzed. To investigate their T cell‐suppressing function, MDSC‐like blasts were isolated using flow cytometry and co‐cultured with CD8⁺ cytotoxic T cells and NB4 leukemic cells. Treatment outcomes were then compared between the MDSC‐like blasts low (≤9.76%) and high (>9.76%) groups to identify clinical significance.Results: MDSC‐like blasts showed higher expression of arginase‐1 and inducible nitric oxide synthase. Isolated MDSC‐like blasts significantly suppressed CD8⁺ T cell proliferation induced by phytohemagglutinin A. NB4 cell proliferation was significantly suppressed upon co‐culture with CD8⁺ cytotoxic T cells and partially restored upon co‐culture with MDSC‐like blasts. Patients with high MDSC‐like blasts at diagnosis showed substantially shorter overall survival and leukemia‐free survival relative to low MDSC‐like blasts patients, with subgroup analysis showing statistically significant differences in patients not receiving allogeneic hematopoietic stem cell transplantation.Conclusion: We demonstrated that MDSC‐like blasts drive AML‐specific immune‐escape mechanisms by suppressing T cell proliferation and restoring T cell‐suppressed NB4 cell proliferation, with clinically higher fractions of MDSC‐like blasts at diagnosis resulting in poor prognosis.

Cytomegalovirus (CMV) disease is a major cause of infectious complications in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Although patients undergoing allo-HSCT receive prophylactic and preemptive treatment for CMV, a subset of patients experience clinically significant CMV disease. This study investigated the risk factors for progression from CMV viremia to CMV disease during or after preemptive therapy in patients undergoing allo-HSCT. Between January 2006 and August 2010, 43 patients received preemptive therapy for CMV viremia after allo-HSCT. These patients experienced 74 episodes of CMV viremia. Nine of the patients (21%) and 12 of the episodes (16%) progressed to CMV disease. Univariate analysis identified several risk factors for progression to CMV disease, including high initial viral load (P = .020), leukopenia (P = .012), and neutropenia (P = .033) at the time of detection of CMV viremia. On multivariate analysis, leukopenia remained an independent predictor (hazard ratio, 4.347; P = .045). The rate of failure to clear CMV viremia after 1 cycle of preemptive therapy was higher in the leukopenia group than in the non-leukopenia group (60.0% versus 16.9%; P = .002). This indicates that leukopenia initially documented with CMV viremia is related to lower viral response to preemptive therapy and is a notable risk factor for progression from CMV viremia to CMV disease.

L-ascorbic acid 2-phosphate (Asc-2P) acts as an antioxidant and a stimulator of hepatocyte growth factor (HGF) production. Previously, we reported that depletion of growth factors such as fibroblast growth factor (FGF)-2, epidermal growth factor (EGF), FGF-4 and HGF during serial passage could induce autophagy, senescence and down-regulation of stemness (proliferation via FGF-2/-4 and differentiation via HGF). In this study, we investigated the proliferation and differentiation potential of BMSCs by FGF-2 and Asc-2P. Co-treatment with FGF-2 and Asc-2P induced optimal proliferation of BMSCs and increased the accumulation rate of BMSC numbers during a 2-month culture period. Moreover, differentiation potential was maintained by co-treatment with FGF-2 and Asc-2P via HGF expression. Adipogenic differentiation potential by FGF-2 and Asc-2P was dramatically suppressed by c-Met inhibitors (SU11274). These data suggest that co-treatment with FGF-2 and Asc-2P would be beneficial in obtaining BMSCs that possess "stemness" during long-term culture.

Kim Y, et al. Yonsei Med J. 2014 Nov;55(6):1568-1575. http://dx.doi.org/10.3349/ymj.2014.55.6.1568