3存在问题

    ESCs的成瘤性是目前ESCs移植面临的困难之一。Arnhold等[21]在移植后的长期观察中，50％的移植眼可以看到畸胎瘤的形成，并侵犯宿主的视网膜，甚至是全眼球受累。这说明ESCs的无限自我更新和高分化潜能在移植后有形成肿瘤的危险，这就要求在使用ESCs进行治疗前，必须先进行体外诱导ESCs分化产生某种特定的组织细胞或设计自杀基因，当移植的细胞向肿瘤发展时，自杀基因能启动自毁程序使其凋亡。而且如何控制ESCs分裂增殖中的突变，产生正常的分化细胞仍需大量实验研究。此外，ESCs的伦理学问题也仍然是目前的争论焦点之一。

    总之， ESCs的自身应用优势虽然为难治性眼科疾病的治疗提供了新的途径，但也存在着大量有待解决的问题。因此，阐明ESCs的定向分化机制、明确向目的细胞分化的诱导条件、基因修饰ESCs将是未来ESCs研究的发展方向。

   【参考文献】

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