Drake B L, Head J R
Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas 75235-9051.
J Reprod Immunol. 1994 Jan;26(1):41-56. doi: 10.1016/0165-0378(93)00866-r.
Short-term cultures of purified murine trophoblast were used to investigate the potential trophic effects of a number of cytokines. Both granulocyte-macrophage colony stimulating factor (GM-CSF) and colony stimulating factor-1 (CSF-1) increased [3H]thymidine (TdR) uptake (3-8 times control values) by trophoblast harvested from placentae on day 12 or 14 of pregnancy. In contrast, interleukin-3 (IL-3) had only a mild stimulatory effect ([3H]TdR uptake 1.5 times control), and IL-2 did not alter the level of DNA synthesis in these cells. Immunocytochemical analysis confirmed that the cells engaged in DNA synthesis were cytokeratin-positive trophoblast cells and revealed that these cells predominantly bore markers (alkaline phosphatase, transferrin receptors) characteristic of trophoblast cells from the placental labyrinth. The increased DNA synthesis observed after exposure to GM-CSF or CSF-1 was not associated with a change in the proportion of nuclei involved in synthesis, nor did it result in significantly increased trophoblast cell numbers in the cultures. These findings suggest that DNA-synthesizing trophoblast cells were not proliferating, but were more likely engaged in endoreduplicative cycles leading to the formation of terminally differentiated trophoblast giant cells. These results caution against the presumption of proliferation when measuring [3H]thymidine incorporation by placental or trophoblast cells in standard in vitro cultures. In addition, taken together with the reports of high levels of CSF-1 in the pregnant uterus and the expression of the CSF-1 receptor on placental trophoblast cells, they suggest that the hemopoietic cytokines may play a role in the differentiation and/or function of trophoblast cells in the developing murine placenta.
利用纯化的小鼠滋养层细胞进行短期培养，以研究多种细胞因子的潜在营养作用。粒细胞-巨噬细胞集落刺激因子（GM-CSF）和集落刺激因子-1（CSF-1）均能使从妊娠第12天或第14天胎盘采集的滋养层细胞对[3H]胸腺嘧啶核苷（TdR）的摄取增加（为对照值的3 - 8倍）。相比之下，白细胞介素-3（IL-3）仅有轻微的刺激作用（[3H]TdR摄取为对照值的1.5倍），而IL-2并未改变这些细胞中的DNA合成水平。免疫细胞化学分析证实，参与DNA合成的细胞是细胞角蛋白阳性的滋养层细胞，并显示这些细胞主要带有胎盘迷路中滋养层细胞特有的标志物（碱性磷酸酶、转铁蛋白受体）。暴露于GM-CSF或CSF-1后观察到的DNA合成增加与参与合成的细胞核比例变化无关，也未导致培养物中滋养层细胞数量显著增加。这些发现表明，进行DNA合成的滋养层细胞并非在增殖，而更可能是参与了导致终末分化的滋养层巨细胞形成的核内复制周期。这些结果警示在标准体外培养中测量胎盘或滋养层细胞的[3H]胸腺嘧啶核苷掺入量时，不可假定细胞在增殖。此外，结合妊娠子宫中CSF-1水平高以及胎盘滋养层细胞上CSF-1受体表达的报道，提示造血细胞因子可能在发育中的小鼠胎盘中滋养层细胞的分化和/或功能中发挥作用。
