Prosper F, Stroncek D, Verfaillie C M
Department of Medicine, University of Minnesota, Minneapolis, USA.
Blood. 1996 Sep 15;88(6):2033-42.
Granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood progenitor cells (PBPC) have successfully been used as stem cells for both autologous and allogeneic transplants. However, little is known concerning the absolute number and phenotype of primitive progenitors, such as long-term culture-initiating cells (LTC-IC) in mobilized PBPC. The aim of our study was to evaluate the capacity of G-CSF to mobilize LTC-IC in the PB of normal individuals and to evaluate the phenotypic and functional characteristics of G-CSF mobilized LTC-IC. G-CSF was administered to 29 healthy volunteers at 7.5 micrograms or 10 micrograms/kg/d subcutaneously (SC) for 5 consecutive days and PBPC were harvested on day 6. Mobilization with G-CSF increased the absolute number of week 5 LTC-IC in PB 60-fold, while the number of CD34+ cells and committed colony forming cells (CFC) was increased sevenfold to 12-fold. The frequency of CFC and week 5 LTC-IC in CD34+ cells selected by fluorescence-activated cell sorter (FACS) from mobilized PBPC was 2 +/- 0.3-fold and 9 +/- 2.2-fold higher respectively than in CD34+ cells selected from unmobilized PBMNC. CFC were enriched in the CD34+ CD38+ and CD34+ HLA-DR+ populations. The absolute number of LTC-IC present in CD34+ CD38- and CD34+ HLA-DR- cells selected by FACS from either mobilized PBPC, unmobilized PBMNC or steady state bone marrow (BM) was similar (0.5% to 2%). In contrast to unmobilized PBMNC or steady state BM CD34+ CD38+ and CD34+ HLA-DR+ cells, which contain less than 0.1% LTC-IC, CD34+ CD38+ and CD34+ HLA-DR+ cells sorted from mobilized PBPC contained 0.5% to 5% of cells capable of sustaining hematopoiesis in long-term cultures for 5 weeks. However, 90% to 95% of LTC-IC present in mobilized CD34+ CD38+ and CD34+ HLA-DR+ cells were not able to sustain hematopoiesis for 8 weeks, while 30% of CD34+ CD38- and CD34+ HLA-DR- LTC-IC present in mobilized PBPC could sustain hematopoiesis for at least 8 weeks. This suggests that the majority of CD34+ CD38+ and CD34+ HLA-DR+ week 5 LTC-IC represent progenitors at an intermediate state of differentiation. We conclude that G-CSF effectively mobilizes LTC-IC in the blood of normal individuals. Although a fraction of these cells has functional characteristics similar to those of steady state PBMNC or BM LTC-IC, more than 85% of mobilized PBPC LTC-IC are CD34+ CD38+ and CD34+ HLA-DR+, capable of sustaining hematopoiesis for 5 weeks, but not for 8 weeks. The functional and phenotypic characterization of primitive and more mature populations of LTC-IC in mobilized PBPC should prove extremely useful in future studies examining the role of these progenitors in engraftment following transplantation.
粒细胞集落刺激因子（G-CSF）动员的外周血祖细胞（PBPC）已成功用作自体和异体移植的干细胞。然而，关于动员的PBPC中原始祖细胞的绝对数量和表型，如长期培养起始细胞（LTC-IC），人们了解甚少。我们研究的目的是评估G-CSF动员正常个体外周血中LTC-IC的能力，并评估G-CSF动员的LTC-IC的表型和功能特征。29名健康志愿者皮下注射（SC）G-CSF，剂量为7.5微克或10微克/千克/天，连续5天，第6天采集PBPC。G-CSF动员使外周血中第5周LTC-IC的绝对数量增加了60倍，而CD34+细胞和定向集落形成细胞（CFC）的数量增加了7至12倍。通过荧光激活细胞分选仪（FACS）从动员的PBPC中选择的CD34+细胞中，CFC和第5周LTC-IC的频率分别比从未动员的外周血单个核细胞（PBMNC）中选择的CD34+细胞高2±0.3倍和9±2.2倍。CFC在CD34+ CD38+和CD34+ HLA-DR+群体中富集。通过FACS从动员的PBPC、未动员的PBMNC或稳态骨髓（BM）中选择的CD34+ CD38-和CD34+ HLA-DR-细胞中存在的LTC-IC的绝对数量相似（0.5%至2%）。与未动员的PBMNC或稳态BM CD34+ CD38+和CD34+ HLA-DR+细胞（其中LTC-IC含量不到0.1%）不同，从动员的PBPC中分选的CD34+ CD38+和CD34+ HLA-DR+细胞含有0.5%至5%能够在长期培养中维持造血5周的细胞。然而，动员的CD34+ CD38+和CD34+ HLA-DR+细胞中存在的LTC-IC的90%至95%不能维持造血8周，而动员的PBPC中存在的CD34+ CD38-和CD34+ HLA-DR- LTC-IC的30%能够维持造血至少8周。这表明大多数CD34+ CD38+和CD34+ HLA-DR+第5周LTC-IC代表处于中间分化状态的祖细胞。我们得出结论，G-CSF有效地动员了正常个体血液中的LTC-IC。尽管这些细胞中的一部分具有与稳态PBMNC或BM LTC-IC相似的功能特征，但超过85%的动员PBPC LTC-IC是CD34+ CD38+和CD34+ HLA-DR+，能够维持造血5周，但不能维持8周。动员的PBPC中原始和更成熟的LTC-IC群体的功能和表型特征在未来研究这些祖细胞在移植后植入中的作用时应被证明非常有用。
