Verfaillie C M, Catanzarro P M, Li W N
Department of Medicine, University of Minnesota, Minneapolis 55454.
J Exp Med. 1994 Feb 1;179(2):643-9. doi: 10.1084/jem.179.2.643.
Factors that induce proliferation of the human hematopoietic stem cell are ill-defined. Primitive hematopoietic progenitors can be maintained and differentiate in stroma-dependent, long-term bone marrow cultures (LTBMC), originally described by Dexter et al. (Dexter, T. M., L. H. Coutinho, E. Spooncer, C. M. Heyworth, C. P. Daniel, R. Schiro, J. Chang, and T. D. Allen. 1990. Molecular Control of Haemopoiesis). However, 70-80% of primitive progenitors capable of reinitiating secondary stromal cultures (LTBMC-initiating cells [IC]) are lost over a period of 5 wk in such cultures. We have recently described a novel "stroma-noncontact" culture system, in which hematopoietic progenitors are separated from the stromal layer by a 0.4-micron microporous filter membrane. Primitive progenitors in such cultures can not only differentiate into committed progenitors, but are also maintained to a greater extent than in "Dexter" cultures. However, still only 50% of the originally seeded LTBMC-IC are recovered at week 5. Since maintenance of primitive progenitors may depend not only on growth-promoting factors but also on factors that inhibit differentiation and/or proliferation, we evaluated the effect of macrophage inflammatory protein 1 alpha (MIP-1 alpha) or "stem cell inhibitor" in combination with the growth-inducing factor interleukin 3 (IL-3) on the recovery of LTBMC-IC from stroma-noncontact cultures. We demonstrate that addition of MIP-1 alpha alone to stroma-noncontact cultures does not change the number of LTBMC-IC present after 8 wk, indicating that this factor may not directly inhibit or stimulate proliferation of primitive progenitors. Addition of the growth stimulatory cytokine, IL-3, alone results in exhaustion of LTBMC-IC after 8 wk of culture, possibly as a result of their terminal differentiation. However, LTBMC-IC can be maintained for at least 8 wk when grown in stroma-noncontact cultures supplemented with both MIP-1 alpha plus IL-3. This effect depends on soluble (ill-defined) stromal factors, and results from a direct interaction of these cytokines with the progenitor population or its progeny, but not the stroma.
诱导人类造血干细胞增殖的因素尚不明确。原始造血祖细胞可在依赖基质的长期骨髓培养（LTBMC）中维持并分化，这种培养方法最初由德克斯特等人描述（德克斯特，T.M.，L.H.库蒂尼奥，E.斯庞塞，C.M.海沃思，C.P.丹尼尔，R.希罗，J.张，以及T.D.艾伦。1990年。造血作用的分子控制）。然而，在这类培养中，70%-80%能够重新启动二次基质培养的原始祖细胞（LTBMC起始细胞[IC]）在5周内会丢失。我们最近描述了一种新型的“基质非接触”培养系统，其中造血祖细胞通过0.4微米的微孔滤膜与基质层分离。这类培养中的原始祖细胞不仅能分化为定向祖细胞，而且比在“德克斯特”培养中能在更大程度上得以维持。然而，到第5周时，最初接种的LTBMC-IC仍只有50%能够回收。由于原始祖细胞的维持可能不仅取决于生长促进因子，还取决于抑制分化和/或增殖的因子，我们评估了巨噬细胞炎性蛋白1α（MIP-1α）或“干细胞抑制剂”与生长诱导因子白细胞介素3（IL-3）联合使用对从基质非接触培养中回收LTBMC-IC的影响。我们证明，单独向基质非接触培养中添加MIP-1α不会改变8周后LTBMC-IC的数量，这表明该因子可能不会直接抑制或刺激原始祖细胞的增殖。单独添加生长刺激细胞因子IL-3会导致培养8周后LTBMC-IC耗竭，这可能是其终末分化的结果。然而，当在补充了MIP-1α加IL-3的基质非接触培养中生长时，LTBMC-IC可以维持至少8周。这种效应取决于可溶性（尚不明确）的基质因子，并且是这些细胞因子与祖细胞群体或其后代直接相互作用的结果，而非与基质相互作用的结果。
