Publication Date:
2020-11-05
Description:
Eltrombopag (EPAG), a thrombopoietin receptor agonist, has been recently added to first-line immunosuppressive therapy (IST) in immune aplastic anemia (AA), significantly improving hematologic recovery and survival (Townsley et al. NEJM 2017), corroborating preclinical data suggesting a direct effect of EPAG on hematopoietic precursors. Here, we analysed the in vivo effects of EPAG on the composition of the hematopoietic stem and progenitor cell (HSPC) compartment after hematologic recovery in human AA patients treated with IST combined with EPAG. Twelve patients with severe immune aplastic anemia who achieved hematologic response six months after initial treatment were invited to participate in the study. Six patients were treated with EPAG associated with cyclosporine and six were treated with rabbit antithymocyte globulin and cyclosporine, but treatment choice was not determined by this study. 25 mL of marrow aspirate was obtained from each patient for multiparametric analysis in an 8-color flow cytometry. Mononuclear cells were separated by gradient density centrifugation and CD34+ cells were purified using magnetic column beads. We used a 9-antibody panel to identify HSPC subpopulations, as follows: hematopoietic stem cells (HSC), CD34+ CD38- CD45RA- CD90+ CD49f+; multipotent progenitor cells (MPP), CD34+ CD38- CD45RA- CD90- CD49f-; multilymphoid progenitor cells (MLP), CD34+ CD38+ CD45RA+ CD10+ CD7-; common myeloid progenitor cells (CMP), CD34+ CD38+ CD45RA- CD135+ CD10- CD7-; granulocyte-monocyte progenitor cells (GMP), CD34+ CD38+ CD45RA+ CD135+ CD10- CD7-; and megakaryocytic-erythroid progenitor cells (MEP), CD34+ CD38+ CD45RA- CD135- CD10- CD7-. Purified marrow CD34+ cells were also assessed in methylcellulose medium and colonies were counted 14 days after triplicate plating. Cell populations and colony formation assay were compared between the two groups using a two-tailed non-parametric Mann-Whitney test. The percentage of CD34+ of total nucleated bone marrow cells was 1.2% (range, 0.28-2.9%) in patients who received IST/EPAG and 0.2% (0.11-0.65%) in those who received IST alone (P
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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