Development of hematopoietic stem cells is a complex process, which has been extensively investigated. Hematopoietic stem cells (HSCs) in mouse fetal liver are highly expanded to prepare for mobilization of HSCs into the fetal bone marrow. It is not completely known how the fetal liver niche regulates HSC expansion without loss of self-renewal ability. We reviewed current progress about the effects of fetal liver niche, chemokine, cytokine, and signaling pathways on HSC self-renewal, proliferation, and expansion. We discussed the molecular regulations of fetal HSC expansion in mouse and zebrafish. It is also unknown how HSCs from the fetal liver mobilize, circulate, and reside into the fetal bone marrow niche. We reviewed how extrinsic and intrinsic factors regulate mobilization of fetal liver HSCs into the fetal bone marrow, which provides tools to improve HSC engraftment efficiency during HSC transplantation. Understanding the regulation of fetal liver HSC mobilization into the fetal bone marrow will help us to design proper clinical therapeutic protocol for disease treatment like leukemia during pregnancy. We prospect that fetal cells, including hepatocytes and endothelial and hematopoietic cells, might regulate fetal liver HSC expansion. Components from vascular endothelial cells and bones might also modulate the lodging of fetal liver HSCs into the bone marrow. The current review holds great potential to deeply understand the molecular regulations of HSCs in the fetal liver and bone marrow in mammals, which will be helpful to efficiently expand HSCs in vitro.

中文翻译：

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胎儿肝造血干细胞动员成小鼠胎儿骨髓的分子调控。

造血干细胞的发育是一个复杂的过程，已被广泛研究。小鼠胎儿肝脏中的造血干细胞（HSC）高度扩增，为动员HSC进入胎儿骨髓做好了准备。尚不完全了解胎儿肝生境如何调节HSC的扩张而不会丧失自我更新的能力。我们审查了有关胎儿肝脏利基，趋化因子，细胞因子和信号通路对HSC自我更新，增殖和扩展的影响的最新进展。我们讨论了小鼠和斑马鱼中胎儿HSC扩增的分子调控。还未知来自胎儿肝脏的HSC如何动员，循环并驻留在胎儿骨髓小生境中。我们回顾了外部因素和内在因素如何调节胎儿肝脏HSC进入胎儿骨髓的动员，它提供了在HSC移植过程中提高HSC移植效率的工具。了解胎儿肝HSC动员进入胎儿骨髓的调控将有助于我们设计合适的临床治疗方案，以进行妊娠期白血病等疾病的治疗。我们预期胎儿细胞，包括肝细胞以及内皮细胞和造血细胞，可能会调节胎儿肝脏HSC的扩增。来自血管内皮细胞和骨骼的成分也可能调节胎儿肝脏HSC进入骨髓。本综述具有深入了解哺乳动物胎肝和骨髓中HSCs的分子调控的巨大潜力，这将有助于有效地扩展HSCs 了解胎儿肝HSC动员进入胎儿骨髓的调控将有助于我们设计合适的临床治疗方案，以治疗怀孕期间的白血病。我们预期胎儿细胞，包括肝细胞以及内皮细胞和造血细胞，可能会调节胎儿肝脏HSC的扩增。来自血管内皮细胞和骨骼的成分也可能调节胎儿肝脏HSC进入骨髓。本综述具有深入了解哺乳动物胎肝和骨髓中HSCs的分子调控的巨大潜力，这将有助于有效地扩展HSCs 了解胎儿肝HSC动员进入胎儿骨髓的调控将有助于我们设计合适的临床治疗方案，以进行妊娠期白血病等疾病的治疗。我们预期胎儿细胞，包括肝细胞以及内皮细胞和造血细胞，可能会调节胎儿肝脏HSC的扩增。来自血管内皮细胞和骨骼的成分也可能调节胎儿肝脏HSC进入骨髓。本综述具有深入了解哺乳动物胎肝和骨髓中HSCs的分子调控的巨大潜力，这将有助于有效地扩展HSCs 包括肝细胞以及内皮细胞和造血细胞在内，可能会调节胎儿肝脏HSC的扩增。来自血管内皮细胞和骨骼的成分也可能调节胎儿肝脏HSC进入骨髓。本综述具有深入了解哺乳动物胎肝和骨髓中HSCs的分子调控的巨大潜力，这将有助于有效地扩展HSCs 包括肝细胞以及内皮细胞和造血细胞在内，可能会调节胎儿肝脏HSC的扩增。来自血管内皮细胞和骨骼的成分也可能调节胎儿肝脏HSC进入骨髓。本综述具有深入了解哺乳动物胎肝和骨髓中HSCs的分子调控的巨大潜力，这将有助于有效地扩展HSCs体外。