Johnson L K, Longenecker J P
Mech Ageing Dev. 1982 Jan;18(1):1-18. doi: 10.1016/0047-6374(82)90025-2.
The replicative lifespan of a cloned strain of adult bovine aortic endothelial cells has been examined by serial passage in culture using conditions where the cells were either dependent on fibroblast growth factor (FGF) for rapid growth or relatively independent on FGF for growth. In FGF-dependent cultures a replicative lifespan of 130 generations was attained with a phase III period which spanned approximately 20 generations. Withdrawal of FGF at generation 55 and repeated passage of such cultures in the absence of the growth factor resulted in the loss of proliferative potential within 15 generations. The morphological changes occurring upon FGF withdrawal were different than those that occurred when cultures senesced in the presence of FGF, FGF withdrawn cells showed a homogeneous increase in cell size and after several passages overgrew one another at confluency. Endothelial cells which senesced in the presence of FGF showed a very heterogeneous distribution of enlarged cells, many of which were binucleated but continued to form a confluent monolayer at high cell densities. Under FGF-independent conditions (begun at generation 48) a replicative lifespan of 105 generations was attained in the presence of the growth factor. FGF withdrawal under these conditions only decreased the replicative lifespan to 95 generations. Under these conditions the morphological changes occurring during phase III were identical in the presence and absence of FGF. Examination of the sensitivity of endothelial cells to FGF as they entered phase III showed that their dose-response characteristics were not qualitatively altered after the onset of phase III, although the number of cells responding to FGF progressively dropped. Comparison of the patterns of proteins synthesized in phase II and phase III cultures showed that phase III cultures even when plated at sparse densities continued to synthesize proteins which were normally observed in phase II confluent cultures. The results indicate that onset of the phase III period in aortic endothelial cells cloned and maintained in the presence of fibroblast growth factor can be delayed to a greated extent if the cells are maintained under conditions where they are made dependent on FGF for rapid growth in culture.
通过在培养中连续传代，在细胞要么依赖成纤维细胞生长因子（FGF）快速生长，要么相对不依赖FGF生长的条件下，研究了成年牛主动脉内皮细胞克隆株的复制寿命。在依赖FGF的培养物中，达到了130代的复制寿命，其中III期持续约20代。在第55代时撤除FGF，并在无生长因子的情况下对这种培养物进行反复传代，导致在15代内增殖潜能丧失。撤除FGF时发生的形态学变化与在FGF存在下培养物衰老时发生的变化不同，撤除FGF的细胞显示细胞大小均匀增加，经过几次传代后，汇合时彼此过度生长。在FGF存在下衰老的内皮细胞显示出扩大细胞的非常不均匀的分布，其中许多是双核的，但在高细胞密度下仍继续形成汇合单层。在不依赖FGF的条件下（从第48代开始），在生长因子存在下达到了105代的复制寿命。在这些条件下撤除FGF只会使复制寿命降至95代。在这些条件下，III期期间在有或没有FGF的情况下发生的形态学变化是相同的。检查内皮细胞进入III期时对FGF的敏感性表明，尽管对FGF作出反应的细胞数量逐渐下降，但在III期开始后它们的剂量反应特征没有定性改变。比较II期和III期培养物中合成的蛋白质模式表明，III期培养物即使以稀疏密度接种，仍继续合成通常在II期汇合培养物中观察到的蛋白质。结果表明，如果将克隆并在成纤维细胞生长因子存在下维持的主动脉内皮细胞置于使其在培养中依赖FGF快速生长的条件下，则III期的开始可以在很大程度上延迟。
