Here we discuss the developmental and homeostatic conditions necessary for Hydra regeneration. Hydra is characterized by populations of adult stem cells paused in the G2 phase of the cell cycle, ready to respond to injury signals. The body column can be compared to a blastema-like structure, populated with multifunctional epithelial stem cells that show low sensitivity to proapoptotic signals, and high inducibility of autophagy that promotes resistance to stress and starvation. Intact Hydra polyps also exhibit a dynamic patterning along the oral–aboral axis under the control of homeostatic organizers whose activity results from regulatory loops between activators and inhibitors. As in bilaterians, injury triggers the immediate production of reactive oxygen species (ROS) signals that promote wound healing and contribute to the reactivation of developmental programs via cell death and the de novo formation of new organizing centers from somatic tissues. In aging Hydra, regeneration is rapidly lost as homeostatic conditions are no longer pro-regenerative.

中文翻译：

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水螅全身再生的细胞、代谢和发育维度

在这里，我们讨论水螅再生所需的发育和稳态条件。Hydra的特点是成体干细胞群体暂停在细胞周期的 G2 期，准备对损伤信号做出反应。体柱可以与胚基样结构进行比较，其中充满了多功能上皮干细胞，对促凋亡信号表现出低敏感性，并且具有高自噬诱导能力，可促进对压力和饥饿的抵抗力。完整的水螅息肉还在稳态组织者的控制下沿着口腔-口腔轴表现出动态模式，其活动是由激活剂和抑制剂之间的调节环路产生的。与两侧对称动物一样，损伤会立即产生活性氧（ROS）信号，促进伤口愈合，并通过细胞死亡和体细胞组织从头形成新的组织中心来重新激活发育程序。在衰老的水螅中，由于稳态条件不再利于再生，再生能力迅速丧失。