Hadland Brandon, Yoshimoto Momoko
Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA; Department of Pediatrics, Division of Pediatric Hematology/Oncology, University of Washington School of Medicine, Seattle, WA, USA.
Center for Stem Cell and Regenerative Medicine, Brown Foundation Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA.
Exp Hematol. 2018 Apr;60:1-9. doi: 10.1016/j.exphem.2017.12.008. Epub 2017 Dec 26.
In adult hematopoiesis, the hematopoietic stem cell (HSC) sits at the top of a hierarchy of hematopoietic progenitors responsible for generating the diverse repertoire of blood and immune cells. During embryonic development, however, the initial waves of hematopoiesis provide the first functioning blood cells of the developing embryo, such as primitive erythrocytes arising in the yolk sac, independently of HSCs. In the field of developmental immunology, it has been recognized that some components of the immune system, such as B-1a lymphocytes, are uniquely produced during the embryonic and neonatal period, suggesting a "layered" development of immunity. Several recent studies have shed new light on the developmental origin of the layered immune system, suggesting complex and sometimes multiple contributions to unique populations of innate-like immune cells from both fetal HSCs and earlier HSC-independent progenitors. In this review, we will attempt to synthesize these studies to provide an integrated model of developmental hematopoiesis and layered immunity that may offer new insights into the origin of HSCs.
在成体造血过程中，造血干细胞（HSC）处于造血祖细胞层级结构的顶端，这些造血祖细胞负责生成种类繁多的血液和免疫细胞。然而，在胚胎发育过程中，早期的造血浪潮会为发育中的胚胎提供首批发挥功能的血细胞，比如在卵黄囊中产生的原始红细胞，这一过程独立于造血干细胞。在发育免疫学领域，人们已经认识到免疫系统的某些成分，如B-1a淋巴细胞，是在胚胎期和新生儿期独特产生的，这表明免疫系统存在“分层”发育现象。最近的几项研究为分层免疫系统的发育起源提供了新线索，提示胎儿造血干细胞和早期独立于造血干细胞的祖细胞对类先天性免疫细胞独特群体的贡献复杂，有时甚至是多重的。在这篇综述中，我们将尝试综合这些研究，以提供一个发育性造血和分层免疫的整合模型，这可能会为造血干细胞的起源提供新的见解。
