Sawai N, Koike K, Ito S, Kurokawa Y, Mwamtemi H H, Kinoshita T, Sakashita K, Higuchi T, Takeuchi K, Shiohara M, Ogami K, Komiyama A
Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan.
Stem Cells. 1999;17(1):45-53. doi: 10.1002/stem.170045.
Although the effect of thrombopoietin (TPO) on megakaryocyte production is well established, its role in the commitment of multipotential hematopoietic progenitors to the megakaryocytic lineage remains to be determined. In the present study, we attempted to clarify the determination process of megakaryocytic lineage as a terminal differentiation pathway under stimulation with TPO. Day 7 cultured cells grown by TPO derived from cord blood CD34+ cells were divided into four subpopulations on the basis of CD34 and CD41 expression. The CD34-/CD41- cells showed the labeling pattern of anti-CD42b and anti-CD9 antibodies closer to that of the CD34+/CD41- cells than the CD34+/CD41+ cells. Replating experiments revealed that approximately 40% of the CD34-/CD41- cells proliferated in response to a combination of growth factors, and more than 80% of them were pure erythroid precursors. However, this subpopulation failed to grow/survive and fell into apoptosis in the presence of TPO alone. In contrast, the CD34+/CD41+ cells, which predominantly contained megakaryocytic precursors, exerted a low but significant proliferative potential in the presence of TPO. The insufficient response to TPO of the CD34-/CD41- cells may result from the apparently low expression of c-MpI, as determined by flow cytometric analysis and reverse transcription-polymerase chain reaction analysis. Therefore, these results suggest that the apoptosis of hematopoietic precursors other than megakaryocytic precursors is related to the determination of the terminal differentiation under the influence of TPO.
尽管血小板生成素（TPO）对巨核细胞生成的作用已得到充分证实，但其在多能造血祖细胞向巨核细胞系定向分化中的作用仍有待确定。在本研究中，我们试图阐明在TPO刺激下巨核细胞系作为终末分化途径的确定过程。由脐血CD34+细胞来源的TPO培养7天的细胞，根据CD34和CD41表达分为四个亚群。CD34-/CD41-细胞显示抗CD42b和抗CD9抗体的标记模式比CD34+/CD41+细胞更接近CD34+/CD41-细胞。再接种实验表明，约40%的CD34-/CD41-细胞在生长因子组合刺激下增殖，其中80%以上为纯红系祖细胞。然而，该亚群在单独存在TPO时无法生长/存活并发生凋亡。相反，主要包含巨核细胞前体的CD34+/CD41+细胞在TPO存在下具有低但显著的增殖潜能。流式细胞术分析和逆转录-聚合酶链反应分析确定，CD34-/CD41-细胞对TPO反应不足可能是由于c-MpI表达明显较低。因此，这些结果表明，除巨核细胞前体之外的造血前体细胞凋亡与TPO影响下的终末分化确定有关。
