Department of Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Center for Advanced Life and Medical Science, Waseda University, TWIns Building, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
Cell Tissue Res. 2013 Jul;353(1):153-64. doi: 10.1007/s00441-013-1624-8. Epub 2013 May 3.
Erythropoiesis occurs in the African clawed frog, Xenopus laevis and is mediated by erythropoietin (xlEPO), a primary regulator of this process. Previously, we have shown that the xlEPO receptor (xlEPOR), which is expressed by erythroid progenitors that respond to xlEPO, is found predominantly in the liver. The aim of the present study was to determine the dynamics of erythropoiesis in the livers of normal and anemic X. laevis by identifying the number and precise location of mature and immature erythrocytes. We quantified mature and immature erythrocyte numbers by o-dianisidine staining or immunohistochemistry and investigated the dynamics of erythropoiesis in normal, acute hemolytic and blood-loss states by in vivo cell proliferation assays with 5-bromo-2'-deoxyuridine (BrdU). We detected 0.12×10(8) xlEPOR(+) BrdU(+) cells in the liver of the normal X. laevis at 24 h after BrdU injection. Frogs presenting with acute hemolytic anemia and pancytopenia show a 10-fold increase in the number of xlEPOR(+)/BrdU(+) cells (approximately 1.30×10(8) cells) in the liver. The xlEPOR(+) cells are found predominantly on the inner wall of hepatic sinusoids. Hematopoietic progenitors that undergo slow cell cycling were also observed in the hepatic sinusoids. This study clarifies the rate of production of mature and immature erythrocytes per day in the liver of X. laevis and the way that these cell numbers change in response to anemia.
红细胞生成发生在非洲爪蟾（Xenopus laevis）中，由促红细胞生成素（erythropoietin，xlEPO）介导，xlEPO 是该过程的主要调节剂。此前，我们已经表明，xlEPO 受体（xlEPOR）在对 xlEPO 有反应的红系祖细胞中表达，主要存在于肝脏中。本研究的目的是通过鉴定成熟和未成熟红细胞的数量和精确位置，确定正常和贫血非洲爪蟾肝脏中红细胞生成的动力学。我们通过邻-二茴香胺染色或免疫组织化学定量成熟和未成熟红细胞的数量，并通过体内 5-溴-2'-脱氧尿苷（BrdU）细胞增殖测定法研究正常、急性溶血性和失血状态下的红细胞生成动力学。我们在 BrdU 注射后 24 小时检测到正常非洲爪蟾肝脏中有 0.12×10(8)个 xlEPOR(+) BrdU(+)细胞。出现急性溶血性贫血和全血细胞减少症的青蛙，肝脏中 xlEPOR(+)/BrdU(+)细胞的数量增加了 10 倍（约 1.30×10(8)个细胞）。xlEPOR(+)细胞主要存在于肝窦的内壁上。还观察到在肝窦中经历缓慢细胞循环的造血祖细胞。这项研究阐明了非洲爪蟾肝脏中每天产生成熟和未成熟红细胞的速度，以及这些细胞数量在应对贫血时的变化方式。
