translation.en: And here is the limitation: adult stem cells are mature cells, and, like mature human beings, these cells are more restricted in their thought and more restricted in their behavior to the wide variety of specialized cell types, as embryonic stem cells [can].
translation.zh: 它有其自身的局限性： 成体干细胞是成熟的细胞， 就像成年人一样， 较难改变它们的思维定势 较难改变它们的行为方式 同时它们也不能像胚胎干细胞一样 分化成很多种 特定的功能细胞。