Kim Chang H
Laboratory of Immunology and Hematopoiesis, Department of Comparative Pathobiology; Purdue Cancer Center, Purdue University, West Lafayette, IN, USA.
J Blood Med. 2010;1:13-9. doi: 10.2147/JBM.S7224. Epub 2010 Mar 23.
Extramedullary hematopoiesis (EH) is defined as hematopoiesis occurring in organs outside of the bone marrow; it occurs in diverse conditions, including fetal development, normal immune responses, and pathological circumstances. During fetal development, before formation of mature marrow, EH occurs in the yolk sac, fetal liver, and spleen. EH also occurs during active immune responses to pathogens. Most frequently, this response occurs in the spleen and liver for the production of antigen-presenting cells and phagocytes. EH also occurs when the marrow becomes inhabitable for stem and progenitor cells in certain pathological conditions, including myelofibrosis, where marrow cells are replaced with collagenous connective tissue fibers. Thus, EH occurs either actively or passively in response to diverse changes in the hematopoietic environment. This article reviews the key features and regulators of the major types of EH.
髓外造血(EH)被定义为发生在骨髓以外器官的造血过程;它发生于多种情况下,包括胎儿发育、正常免疫反应和病理状态。在胎儿发育过程中,在成熟骨髓形成之前,髓外造血发生于卵黄囊、胎儿肝脏和脾脏。髓外造血也发生在对病原体的活跃免疫反应期间。最常见的是,这种反应发生在脾脏和肝脏,以产生抗原呈递细胞和吞噬细胞。在某些病理状态下,当骨髓对干细胞和祖细胞变得不适宜居住时,也会发生髓外造血,包括骨髓纤维化,此时骨髓细胞被胶原结缔组织纤维所取代。因此,髓外造血是对造血环境的各种变化做出主动或被动反应而发生的。本文综述了主要类型髓外造血的关键特征和调节因子。