Okada S, Nakauchi H, Nagayoshi K, Nishikawa S, Miura Y, Suda T
Department of Medicine, Jichi Medical School, Tochigi-ken, Japan.
Blood. 1992 Dec 15;80(12):3044-50.
c-kit is expressed on hematopoietic stem cells and progenitor cells, but not on lymphohematopoietic differentiated cells. Lineage marker-negative, c-kit-positive (Lin-c-kit+) bone marrow cells were fractionated by means of Ly6A/E or Sca-1 expression. Lin-c-kit+Sca-1+ cells, which consisted of 0.08% of bone marrow nucleated cells, did not contain day-8 colony-forming units-spleen (CFU-S), but 80% were day-12 CFU-S. One hundred cells rescued the lethally irradiated mice and reconstituted hematopoiesis. On the other hand, 2 x 10(3) of Lin-c-kit+Sca-1- cells formed 20 day-8 and 11 day-12 spleen colonies, but they could not rescue the lethally irradiated mice. These data indicate that Lin-c-kit+Sca-1+ cells are primitive hematopoietic stem cells and that Sca-1-cells do not contain stem cells that reconstitute hematopoiesis. Lin-c-kit+Sca-1+ cells formed no colonies in the presence of stem cell factor (SCF) or interleukin-6 (IL-6), and only 10% of them formed colonies in the presence of IL-3. However, approximately 50% of them formed large colonies in the presence of IL-3, IL-6, and SCF. Moreover, when single cells were deposited into culture medium by fluorescence-activated cell sorter clone sorting system, 40% of them proliferated on a stromal cell line (PA-6) and proliferated for more than 2 weeks. In contrast, 15% of the Lin-c-kit+Sca-1-cells formed colonies in the presence of IL-3, but no synergistic effects were observed in combination with SCF plus IL-6 and/or IL-3. Approximately 10% proliferated on PA-6, but most of them degenerated within 2 weeks. The population ratio of c-kit+Sca-1+ to c-kit+Sca-1- increased 2 and 4 days after exposure to 5-fluorouracil (5-FU). These results are consistent with the relative enrichment of highly proliferative colony-forming cells by 5-FU. These data show that, although c-kit is found both on the primitive hematopoietic stem cells and progenitors, Sca-1+ cells are more primitive and respond better than Sca-1- cells to a combination of hematopoietic factors, including SCF and stromal cells.
c-kit在造血干细胞和祖细胞上表达，但在淋巴造血分化细胞上不表达。通过Ly6A/E或Sca-1表达对谱系标志物阴性、c-kit阳性（Lin-c-kit+）的骨髓细胞进行分选。Lin-c-kit+Sca-1+细胞占骨髓有核细胞的0.08%，不包含第8天的脾集落形成单位（CFU-S），但80%是第12天的CFU-S。100个这样的细胞就能拯救受致死性照射的小鼠并重建造血功能。另一方面，2×10³个Lin-c-kit+Sca-1-细胞形成了20个第8天的和11个第12天的脾集落，但它们不能拯救受致死性照射的小鼠。这些数据表明，Lin-c-kit+Sca-1+细胞是原始造血干细胞，而Sca-1-细胞不包含能重建造血功能的干细胞。Lin-c-kit+Sca-1+细胞在存在干细胞因子（SCF）或白细胞介素-6（IL-6）时不形成集落，在存在IL-3时只有10%形成集落。然而，在存在IL-3、IL-6和SCF时，约50%的细胞形成大集落。此外，当通过荧光激活细胞分选仪克隆分选系统将单个细胞接种到培养基中时，40%的细胞在基质细胞系（PA-6）上增殖并持续增殖超过2周。相比之下，15%的Lin-c-kit+Sca-1-细胞在存在IL-3时形成集落，但与SCF加IL-6和/或IL-3联合使用时未观察到协同效应。约10%的细胞在PA-6上增殖，但大多数在2周内退化。暴露于5-氟尿嘧啶（5-FU）后2天和4天，c-kit+Sca-1+与c-kit+Sca-1-的细胞群体比例增加。这些结果与5-FU对高增殖集落形成细胞的相对富集作用一致。这些数据表明，虽然c-kit在原始造血干细胞和祖细胞上均有发现，但Sca-1+细胞更原始，并且比Sca-1-细胞对包括SCF和基质细胞在内的造血因子组合反应更好。
