Brain organoids 'record time' in seven-year lab study

Human brain organoids grown in a laboratory for around seven years continued to mature and appeared to record earlier developmental steps at a cellular level, scientists said in a study published in Nature.

The peppercorn-sized clumps of cells were grown from stem cells by a US-led team. Paola Arlotta, a Harvard University professor and senior author of the study, told AFP they were the “oldest ever” brain organoids, exceeding a previous record of a little under two years cited in the study.

The researchers said the organoids changed over time in ways similar to normal brain cells, even though they had never developed inside an embryo or body. The team analysed them with three genetic “clocks” designed to estimate the biological age of cells.

The Nature study said the organoids “recorded the passage of time and retain a memory of the developmental steps already performed.” Arlotta said this did not mean they had memories in the ordinary sense, but that their past was marked at a cellular level.

Organoids are used as biological models of human brain cells and are far less complex than a human brain. Arlotta said they do not receive sensory input, and scientists widely agree they are not capable of consciousness or other higher-order brain functions.

The team also mixed cells that had been developing for a year with cells that were two weeks old. Arlotta said the older cells advanced development and began making neurons that normally take around four months, suggesting the method could one day help speed up the development of some brain cells for research.

The scientists hope longer-lived brain organoids could help researchers study how disorders such as autism and schizophrenia first emerge and later progress. The organoids used in the new research have since been destroyed.