The characters in the novel were clones of humans in the “outside” world, and their lives were set up to donate their vital organs until their death. This ordeal of creating clones to benefit the “outside” world of humans, relates to what Miss Lucy states in Never Let Me Go, she states:
You’ll become adults, then before you’re old, before you’re even middle-aged, you’ll start to donate your vital organs. That’s what each of you was created to do. You’re not like the actors you watch on your videos, you’re even not like me. You were brought into this world for a purpose, and your futures, all of them, have been decided. So you’re not to talk that way anymore. (Ishiguro 81)
This quote emphasizes the idea of how the characters’ lives were already mapped out for them to donate and die. Clones are used for “dummies” of their organs because, they are genetically modified from humans, and if they lose their organs and die it would be legally possible because, they’re not human. In the blog AGreenRoadProject, it expands this idea