Rapamycin enhances long-term hematopoietic reconstitution of ex vivo expanded mouse hematopoietic stem cells by inhibiting senescence.
Rapamycin enhances long-term hematopoietic reconstitution of ex vivo expanded mouse hematopoietic stem cells by inhibiting senescence.
复制标题
雷帕霉素通过抑制衰老增强离体扩增小鼠造血干细胞的长期造血重建
DOI：
10.1097/tp.0b013e3182a7fcf8
复制
发表时间：
2014-01-15
期刊：
影响因子：
6.2
通讯作者：
Liu L
中科院分区：
文献类型：
--
作者：
Luo Y;Li L;Zou P;Wang J;Shao L;Zhou D;Liu L
哺乳动物雷帕霉素靶蛋白（mTOR）是造血干细胞（HSC）自我更新的重要调节因子，其过度激活可诱导HSC衰老，导致HSC过早衰竭。用雷帕霉素抑制mTOR具有促进离体扩增的HSC的长期造血的潜力，以促进HSC移植用于各种血液病的临床应用。方法利用小鼠骨髓造血干细胞体外扩增系统，研究雷帕霉素抑制过度激活的mTOR是否能促进体外扩增的造血干细胞的长期造血功能，并探讨雷帕霉素的作用机制。结果HSC富集的小鼠骨髓LSK细胞在添加干细胞因子、血小板生成素和Flt3配体的无血清培养基中体外扩增后，mTOR表现出时间依赖性激活。mTOR的过度激活与LSK细胞中衰老的诱导而非凋亡以及HSC产生长期造血重建的能力的显著降低相关。用雷帕霉素抑制过度活化的mTOR促进HSC的离体扩增和长期造血重建。扩增的HSC的长期造血的增加可能部分归因于雷帕霉素介导的Bmi 1的上调和p16的下调，其防止HSC在离体扩增期间经历衰老。结论mTOR在HSC体外自我更新过程中起重要调节作用，雷帕霉素抑制mTOR的过度激活可能是促进HSC体外扩增和长期造血重建的新途径。
Background The mammalian target of rapamycin (mTOR) is an important regulator of hematopoietic stem cell (HSC) self-renewal and its overactivation contributes to HSC premature exhaustion in part via induction of HSC senescence. Inhibition of mTOR with rapamycin has the potential to promote long-term hematopoiesis of ex vivo expanded HSCs to facilitate the clinical application of HSC transplantation for various hematologic diseases. Methods A well-established ex vivo expansion system for mouse bone marrow HSCs was used to investigate whether inhibition of overactivated mTOR with rapamycin can promote long-term hematopoiesis of ex vivo expanded HSCs and to elucidate the mechanisms of action of rapamycin. Results HSC-enriched mouse bone marrow LSK cells exhibited a time-dependent activation of mTOR after ex vivo expansion in a serum-free medium supplemented with stem cell factor, thrombopoietin, and Flt3 ligand. The overactivation of mTOR was associated with induction of senescence but not apoptosis in LSK cells and a significant reduction in the ability of HSCs to produce long-term hematopoietic reconstitution. Inhibition of overactivated mTOR with rapamycin promoted ex vivo expansion and long-term hematopoietic reconstitution of HSCs. The increase in long-term hematopoiesis of expanded HSCs is likely attributable in part to rapamycin-mediated up-regulation of Bmi1 and down-regulation of p16, which prevent HSCs from undergoing senescence during ex vivo expansion. Conclusions These findings suggest that mTOR plays an important role in the regulation of HSC self-renewal in vitro and inhibition of mTOR hyperactivation with rapamycin may represent a novel approach to promote ex vivo expansion and their long-term hematopoietic reconstitution of HSCs.