Kreja L, Thoma S, Selig C, Lamping C, Ziegler B L, Nothdurft W
Institute for Occupational and Social Medicine, University of Ulm, Germany.
Exp Hematol. 1993 Oct;21(11):1436-41.
Human umbilical cord blood (CB) cells selected by immunomagnetic beads for expression of the CD34 antigen were irradiated with increasing doses of x-rays (72 cGy/min). Clonogenic survival of the hematopoietic progenitors, including mixed colony-forming cells (Mix-CFC), erythroid burst-forming units (BFU-E), and granulocyte-macrophage colony-forming cells (GM-CFC), was determined in methylcellulose cultures containing placenta conditioned medium (PCM) and erythropoietin (Epo). Exponential survival curves were fitted to the data of all the colonies, resulting in D0 = 95 cGy for Mix-CFC, 136 cGy for BFU-E, and 136 cGy for GM-CFC. Additionally, the radiosensitivity of CD34+ cells was studied employing cultures containing either recombinant human stem cell factor (rhSCF) or basic fibroblast growth factor (b-FGF) in combination with PCM and Epo. It was found that the colony-forming efficiency (CFE) of non-irradiated CD34+ cells of 5.5% (range 1.4 to 14.4%) did not increase after the addition of SCF or b-FGF to the culture. The radiation response characteristics showed, however, that in the presence of SCF, the D0 value and the extrapolation number n increased significantly. This suggests the stimulation of what operationally is termed "recovery from potentially lethal damage." In contrast, no response modifying effect could be seen for b-FGF.
用免疫磁珠筛选出表达CD34抗原的人脐带血（CB）细胞，以递增剂量的X射线（72 cGy/分钟）进行照射。在含有胎盘条件培养基（PCM）和促红细胞生成素（Epo）的甲基纤维素培养基中，测定包括混合集落形成细胞（Mix-CFC）、红系爆式集落形成单位（BFU-E）和粒-巨噬细胞集落形成细胞（GM-CFC）在内的造血祖细胞的克隆形成存活率。对所有集落的数据拟合指数存活曲线，得出Mix-CFC的D0为95 cGy，BFU-E为136 cGy，GM-CFC为136 cGy。此外，在含有重组人干细胞因子（rhSCF）或碱性成纤维细胞生长因子（b-FGF）并结合PCM和Epo的培养基中，研究了CD34+细胞的放射敏感性。结果发现，在培养基中添加SCF或b-FGF后，未照射的CD34+细胞的集落形成效率（CFE）为5.5%（范围为1.4%至l4.4%）并未增加。然而，放射反应特征表明，在存在SCF的情况下，D0值和外推数n显著增加。这表明对实际上所谓的“潜在致死性损伤的修复”有刺激作用。相比之下，未观察到b-FGF有反应修饰作用。
