Tocci A, Rezzoug F, Wahbi K, Touraine J L
Transplantation and Clinical Immunology Unit, INSERM U 80, Lyon, France.
Blood. 1995 Mar 15;85(6):1463-71.
We have demonstrated that 0.2% to 11% of cells from the fetal liver (FL) reacted specifically with high concentrations of anti-CD4 monoclonal antibody (MoAb). CD4+ cells from FL were similar in surface phenotype and fluorescence characteristics to the CD4+ population found previously in adult bone marrow (BM). FL and BM cells were seeded in cultures that allow differentiation to primitive precursors. FL cells released many low CD4+ and low Thy+ cells in the supernatant, while BM cells seeded under the same conditions did not. We studied the nonadherent cells harvested from 10-day FL cultures (greater than 90% low CD4+). In methylcellulose, they were able to produce more colonies that appear to be characteristic of earlier stages in the hierarchy of hematopoietic precursors (especially erythroid bursts and colonies composed of both myeloid and erythroid elements) in comparison with CD4- cells from 10-day BM cultures. CD4+ cells harvested from FL cultures initiated secondary cultures containing both a stromal layer and large hematopoietic colonies when replated under conditions similar to those of primary cultures. Furthermore, a limited number of CD4+ cells from 10-day FL cultures were able to repopulate lethally irradiated mice. Although we cannot formally exclude the possibility that the low CD4 cells produced in FL cultures were derived exclusively from the proliferation of the few CD4 cells found in fresh FL, the dynamic analysis of the development of these cells in culture favors the generation of this important population from a CD4- subset of hematopoietic stem cells (HSCs). We speculate that FL contains a prevalent population of very primitive cells not expressing the CD4 antigen, tentatively called "pre-low CD4 precursors." These primitive cells can differentiate into low CD4+ cells that share many characteristics with pluripotent HSCs of the adult type. These data indicate the possibility of using hematopoietic progenitors obtained by the expansion/differentiation of fetal stem cells in culture for transplantation purposes.
我们已经证明，来自胎肝（FL）的0.2%至11%的细胞能与高浓度的抗CD4单克隆抗体（MoAb）发生特异性反应。胎肝中的CD4+细胞在表面表型和荧光特征上与先前在成人骨髓（BM）中发现的CD4+群体相似。将胎肝和骨髓细胞接种到允许分化为原始前体的培养物中。胎肝细胞在上清液中释放出许多低CD4+和低Thy+细胞，而在相同条件下接种的骨髓细胞则没有。我们研究了从10天龄胎肝培养物中收获的非贴壁细胞（超过90%为低CD4+）。在甲基纤维素中，与来自10天龄骨髓培养物的CD4-细胞相比，它们能够产生更多的集落，这些集落似乎具有造血前体层次结构中早期阶段的特征（特别是红系爆发集落以及由髓系和红系成分组成的集落）。当在与原代培养相似的条件下重新接种时，从胎肝培养物中收获的CD4+细胞启动了含有基质层和大型造血集落的二次培养。此外，来自10天龄胎肝培养物的有限数量的CD4+细胞能够使受致死性照射的小鼠重建造血。尽管我们不能完全排除胎肝培养物中产生的低CD4细胞仅来自新鲜胎肝中少数CD4细胞增殖的可能性，但对这些细胞在培养中发育的动态分析有利于从造血干细胞（HSC）的CD4-亚群产生这一重要群体。我们推测胎肝中含有大量不表达CD4抗原的非常原始的细胞，暂称为“前低CD4前体”。这些原始细胞可以分化为低CD4+细胞，这些细胞与成人型多能造血干细胞有许多共同特征。这些数据表明，有可能将通过培养胎儿干细胞的扩增/分化获得的造血祖细胞用于移植目的。
