“No one wanted to believe it,” said molecular geneticist Hans Clevers.

In 2009, Clevers and his team had demonstrated an unusual new method of creating tiny, out-of-the-body replicas of human organs that could be used to study disease. These replicas were 3-dimensional organoids generated from human cells that perfectly replicated the structure of cells lining the intestine, and therefore could be studied and tested without using human volunteers.

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“Heart-on-a-chip” causes most live hearts to skip a beat. People are “not going to get upset about making a pancreas,” Stanford University’s Bioethics Law professor Henry Greely told The Scientist in 2016. “But the closer you come to making a human brain, the more issues get raised.” Bodies-on-a-chip seem too Frankenstein-esque for some.