Teitell Michael A, Mikkola Hanna K A
Department of Pathology and Laboratory Medicine, University of California at Los Angeles, 90095, USA.
Pediatr Res. 2006 Apr;59(4 Pt 2):33R-9R. doi: 10.1203/01.pdr.0000205155.26315.c7.
Hematopoietic stem cells (HSCs) are pluripotent cells that give rise to all of the circulating blood cell types. Their unique ability to self-renew while generating differentiated daughter cells permits HSCs to sustain blood cell production throughout life. In mammals, the pool of HSCs shifts from early sites in the aorta-gonad-mesonephros region and the placenta to the fetal liver and ultimately bone marrow. During the past decade, a map of transcriptional activators and repressors that regulate gene expression in HSCs, their precursors and their progeny, at distinct stages of development has been drafted. These factors control a program that first establishes the pool of HSCs in the fetus, and later guides decisions between quiescence, self-renewal, and lineage commitment with progressive differentiation to maintain homeostasis. Continuing studies of the regulatory mechanisms that control HSC gene expression followed by the identification of specific loci that are activated or silenced during the life of an HSC will help to further elucidate longstanding issues in HSC decisions to self-renew or to differentiate, and to define the origins of and connections between distinct HSC pools and their precursors.
造血干细胞（HSCs）是多能细胞，可产生所有循环血细胞类型。它们具有独特的自我更新能力，同时产生分化的子代细胞，这使得造血干细胞能够在一生中维持血细胞生成。在哺乳动物中，造血干细胞库从主动脉-性腺-中肾区域和胎盘的早期位点转移到胎儿肝脏，最终转移到骨髓。在过去十年中，已经绘制了一张转录激活因子和抑制因子的图谱，这些因子在发育的不同阶段调节造血干细胞、其前体及其子代中的基因表达。这些因子控制着一个程序，该程序首先在胎儿中建立造血干细胞库，然后在静止、自我更新和谱系定向之间做出决定，并随着渐进分化维持体内平衡。对控制造血干细胞基因表达的调控机制的持续研究，以及随后对在造血干细胞生命周期中被激活或沉默的特定基因座的鉴定，将有助于进一步阐明造血干细胞自我更新或分化决定中的长期问题，并确定不同造血干细胞库及其前体的起源和联系。
