Mini brains, big questions: Science is racing ahead of ethics

In a little over 10 years, organoid models — miniature, lab-grown clusters of cells that imitate real organs-have transformed how we study human development and disease while accelerating drug discovery.

- JAMES POULTER

As a bonus, they've reduced our reliance on animal testing.Among these models, brain organoids — 3D, brain-like structures grown from stem cells - have progressed from simple cell clusters to sophisticated models that mimic important aspects of brain development and function.

Recent breakthroughs have made them more complex: some organoids now show electrical activity similar to what is seen in a very early-stage human foetus. Others form networks of nerve cells that can send signals back and forth, in a similar way to how real brains communicate.

These advances promise deeper insights into brain disorders such as Alzheimer's and schizophrenia, and could revolutionise drug testing and personalised medicine. Yet, as complexity grows, so does ethical unease.

Bioethicists warn that current rules for human and animal research don't fit well for things that come from human cells, are alive, and are becoming more like real brains.

Under controlled conditions, brain organoids can self-organise into layers resembling - at a very basic level-the developing human brain.