We assessed the mechanism of hematopoietic stem cell (HSC) mobilization using etoposide with granulocyte-colony stimulating factor (G-CSF), and determined how this mechanism differs from that induced by cyclophosphamide with G-CSF or G-CSF alone. We compared the clinical features of 173 non-Hodgkin’s lymphoma patients who underwent autologous peripheral blood stem cell transplantation (auto-PBSCT). Additionally, we performed in vitro experiments to assess the changes in human bone marrow stromal cells (hBMSCs), which support the HSCs in the bone marrow (BM) niche, following cyclophosphamide or etoposide exposure. We also performed animal studies under standardized conditions to ensure the following: exclude confounding factors, mimic the conditions in clinical practice, and identify the changes in the BM niche caused by etoposide-induced chemo-mobilization or other mobilization methods. Retrospective analysis of the clinical data revealed that the etoposide with G-CSF mobilization group showed the highest yield of CD34+ cells and the lowest change in white blood cell counts during mobilization. In in vitro experiments, etoposide triggered interleukin (IL)-8 secretion from the BMSCs and caused long-term BMSC toxicity. To investigate the manner in which the hBMSC-released IL-8 affects hHSCs in the BM niche, we cultured hHSCs with or without IL-8, and found that the number of total, CD34+, and CD34+/CD45- cells in IL-8-treated cells was significantly higher than the respective number in hHSCs cultured without IL-8 (p = 0.014, 0.020, and 0.039, respectively). Additionally, the relative expression of CXCR2 (an IL-8 receptor), and mTOR and c-MYC (components of IL-8-related signaling pathways) increased 1 h after IL-8 treatment. In animal studies, the etoposide with G-CSF mobilization group presented higher IL-8-related cytokine and MMP9 expression and lower SDF-1 expression in the BM, compared to the groups not treated with etoposide. Collectively, the unique mechanism of etoposide with G-CSF-induced mobilization is associated with IL-8 secretion from the BMSCs, which is responsible for the enhanced proliferation and mobilization of HSCs in the bone marrow; this was not observed with mobilization using cyclophosphamide with G-CSF or G-CSF alone. However, the long-term toxicity of etoposide toward BMSCs emphasizes the need for the development of more efficient and safe chemo-mobilization strategies.

中文翻译：

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依托泊苷介导的骨髓基质细胞分泌白介素8诱导造血干细胞动员。

我们使用依托泊苷与粒细胞集落刺激因子（G-CSF）评估了造血干细胞（HSC）动员的机制，并确定了该机制与单独使用G-CSF或G-CSF的环磷酰胺诱导的机制有何不同。我们比较了173例接受自体外周血干细胞移植（auto-PBSCT）的非霍奇金淋巴瘤患者的临床特征。此外，我们进行了体外实验，以评估人骨髓基质细胞（hBMSCs）的变化，后者在环磷酰胺或依托泊苷暴露后支持骨髓（BM）小生境中的HSC。我们还在标准化条件下进行了动物研究，以确保以下各项：排除混杂因素，在临床实践中模仿条件，并确定由依托泊苷诱导的化学动员或其他动员方法引起的BM生态位变化。临床数据的回顾性分析显示，G-CSF动员组的依托泊苷在动员期间显示出最高的CD34 +细胞产量和最低的白细胞计数变化。在体外实验中，依托泊苷触发BMSCs分泌白介素（IL）-8，并引起BMSC长期毒性。为了研究hBMSC释放的IL-8影响BM生态位中的hHSC的方式，我们培养了有或没有IL-8的hHSC，发现IL-8中的总数，CD34 +和CD34 + / CD45-细胞的数量在没有IL-8的情况下培养的hHSC中，经处理的细胞明显高于各自的数目（分别为p = 0.014、0.020和0.039）。另外，IL-8治疗后1小时，CXCR2（一种IL-8受体）以及mTOR和c-MYC（与IL-8相关的信号通路的组成部分）的相对表达增加。在动物研究中，与未用依托泊苷治疗的组相比，G-CSF动员的依托泊苷在BM中表现出较高的IL-8相关细胞因子和MMP9表达，而SDF-1表达较低。总的来说，依托泊苷与G-CSF诱导的动员的独特机制与BMSCs分泌IL-8有关，后者促进了骨髓中HSC的增殖和动员。使用环磷酰胺与单独的G-CSF或G-CSF进行动员时未观察到此现象。然而，依托泊苷对BMSC的长期毒性强调需要开发更有效和安全的化学动员策略。IL-8治疗后1小时，mTOR和c-MYC（IL-8相关信号通路的组成部分）增加。在动物研究中，与未用依托泊苷治疗的组相比，G-CSF动员的依托泊苷在BM中表现出较高的IL-8相关细胞因子和MMP9表达，而SDF-1表达较低。总的来说，依托泊苷与G-CSF诱导的动员的独特机制与BMSCs分泌IL-8有关，后者促进了骨髓中HSC的增殖和动员。使用环磷酰胺与单独的G-CSF或G-CSF进行动员时未观察到此现象。然而，依托泊苷对BMSC的长期毒性强调需要开发更有效和安全的化学动员策略。IL-8治疗后1小时，mTOR和c-MYC（IL-8相关信号通路的组成部分）增加。在动物研究中，与未用依托泊苷治疗的组相比，G-CSF动员的依托泊苷在BM中具有更高的IL-8相关细胞因子和MMP9表达，而在SDF-1表达则较低。总的来说，依托泊苷与G-CSF诱导的动员的独特机制与BMSCs分泌IL-8有关，后者促进了骨髓中HSC的增殖和动员。使用环磷酰胺与单独的G-CSF或G-CSF进行动员时未观察到此现象。然而，依托泊苷对BMSC的长期毒性强调需要开发更有效和安全的化学动员策略。