Palmberg L, Thyberg J
Cell Tissue Res. 1986;246(2):253-62. doi: 10.1007/BF00215887.
Smooth muscle cells (SMC) were enzymatically isolated from the myometrium of adult rat and human uteri and grown in primary culture. Cell fine structure and cytoskeletal organization were followed by transmission electron microscopy and cytochemical demonstration of actin filaments, microtubules and intermediate filaments, and initiation of DNA synthesis was investigated by thymidine autoradiography. During the first few days in culture the cells spread out on the substrate and went through a morphological transformation including loss of myofilaments followed by formation of an extensive rough endoplasmic reticulum and a large Golgi complex. Actin filaments aggregated in stress fibers spanning the entire length of the cells and microtubules and intermediate filaments formed a radiating system originating in the juxtanuclear region. In vivo, the SMC contained intermediate filaments reactive for desmin, but as early as the first day of culture expressed vimentin as well. For five days at least, all cells remained positive for both proteins, but the staining for desmin decreased while that for vimentin increased. This structural modification was accompanied by initiation of DNA synthesis, with a peak on day 3 (45-55% labeled nuclei). Subconfluent, growth-arrested primary cultures responded weakly to purified platelet-derived growth factor and serum, and in secondary cultures no response to the mitogenic stimulation was obtained. The observations indicate that uterine SMC cultivated in vitro undergo a transformation from contractile to synthetic phenotype, similar to the transformation described previously for arterial SMC under the same conditions. The proliferative potential of the uterine cells is, however, markedly lower. The findings support the notions that the transition into synthetic phenotype is a necessary but not sufficient requirement for initiation of DNA synthesis in SMC and that visceral and vascular SMC represent separate differentiation pathways.
平滑肌细胞（SMC）从成年大鼠和人类子宫肌层中酶解分离出来，并进行原代培养。通过透射电子显微镜、肌动蛋白丝、微管和中间丝的细胞化学显示来观察细胞精细结构和细胞骨架组织，并通过胸腺嘧啶核苷放射自显影研究DNA合成的起始。在培养的最初几天里，细胞在底物上铺展并经历形态转变，包括肌丝丧失，随后形成广泛的粗面内质网和大型高尔基体复合体。肌动蛋白丝聚集在横跨细胞全长的应力纤维中，微管和中间丝形成一个起源于近核区域的辐射系统。在体内，SMC含有对结蛋白有反应的中间丝，但早在培养的第一天就也表达波形蛋白。至少五天内，所有细胞对这两种蛋白均保持阳性，但结蛋白的染色减少，而波形蛋白的染色增加。这种结构修饰伴随着DNA合成的起始，在第3天达到峰值（45 - 55%的标记核）。亚汇合、生长停滞的原代培养物对纯化的血小板衍生生长因子和血清反应微弱，在传代培养中未获得对有丝分裂刺激的反应。这些观察结果表明，体外培养的子宫SMC经历了从收缩表型到合成表型的转变，类似于先前在相同条件下描述的动脉SMC的转变。然而，子宫细胞的增殖潜力明显较低。这些发现支持以下观点：向合成表型的转变是SMC中DNA合成起始的必要但不充分条件，并且内脏和血管SMC代表不同的分化途径。
