Transient nature of early haematopoietic spleen colonies
Transient nature of early haematopoietic spleen colonies
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早期造血脾集落的短暂性
作者：
M. Magli;N. Iscove;N. Odartchenko
在强照射受体小鼠体内注射7-14天后，小鼠造血组织中的某些细胞(CFU-S)能够在脾内形成肉眼可见的结节。在7-9天，大多数脾细胞集落含有一种主要造血系的可识别细胞2，而不包含能够在次要宿主3注射时形成脾细胞集落的细胞。然而，到14天时，大多数脾克隆确实含有多于一种造血系分化的细胞2，以及能够在再次移植时再次产生类似的多线脾克隆的前体细胞3。这些观察导致了被广泛接受的结论，即大多数脾克隆来自多潜能的‘干细胞’3，并暗示脾克隆的特征从早期的单线细胞到后来的混合细胞的明显变化反映了脾环境中‘指导性’分化信号的局部运作2。这些建议背后的推理隐含地假设，较晚的殖民地只是代表了在较早时期可观察到的相同殖民地发展的进一步阶段。在这里，我们提出了反对这一假设的直接证据。我们的数据表明，大多数在第7-8天被鉴定为表面结节的脾集落既不是多潜能的，也不是自我维持的，而是注定在72小时内从脾中消失。这些观察结果限制了脾集落方法作为自我维持的多潜能祖细胞的检测的有效性，并导致了对广泛接受的关于这类细胞调节的观点所基于的数据的重新评估。
Certain cells (CFU-S) in the haematopoietic tissues of mice are able to form macroscopic nodules in the spleen 7–14 days after injection in heavily irradiated recipient mice1. At 7–9 days, most of the spleen colonies contain recognizable cells of one predominant haematopoietic lineage2, and do not contain cells capable of spleen colony formation on injection in secondary hosts3. However, by 14 days most of the spleen colonies do contain cells of more than one line of haematopoietic differentiation2, as well as precursor cells capable of again generating similar multilineal spleen colonies on retransplantation3. These observations have led to the widely accepted conclusion that most spleen colonies are derived from pluripotential ‘stem’ cells3, and to the suggestion that the apparent transformation in character of spleen colonies from unilineal at early times to mixed later on reflects the local operation of ‘instructive’ differentiative signals in the splenic environment2. The reasoning behind these suggestions implicitly assumed that late colonies simply represented a further stage in the development of the same colonies observable at earlier times. Here, we present direct evidence against this assumption. Our data indicate that most spleen colonies identified as surface nodules at days 7–8 are neither multipotential nor self-maintaining, but rather are destined to disappear from the spleen within 72 h. The observations set limits on the validity of the spleen colony method as an assay for self-maintaining pluripotential progenitor cells, and give cause for reassessment of the data on which widely accepted views concerning the regulation of such cells are based.