Brain organoids continue developing for seven years outside the human body

Human brain organoids grown in a lab for a record seven years have continued to mature, mirroring the aging process of cells within a human brain. This groundbreaking research, led by Harvard University, indicates that these "brain organoids" can follow developmental pathways and a sense of "time passing" even when not developing within an embryo or human body.

These organoids, derived from stem cells, serve as simplified 3D models of human organs. Scientists utilize them to study brain development and diseases, and to test potential treatments without direct human or animal experimentation. Typically, brain organoids are cultivated for only a few months, offering insights primarily into the earliest stages of human brain development, which normally takes nearly two decades to mature.

Paola Arlotta, the study's lead author and a professor at Harvard, stated that the seven-year-old organoids are the oldest studied to date. The research, published in the journal Nature, found that these organoids retained traces of their developmental stages, effectively showing a cellular "memory" of their progression. However, Arlotta clarified that this is not human memory but rather a cellular imprint of their developmental history.

While these organoids are biological approximations of human brain tissue, they are significantly less complex than actual human brains and do not receive sensory input. The scientific consensus is that such organoids do not possess consciousness or higher brain functions. The experiment, described by Arlotta as a "crazy experiment," utilized three types of genetic and molecular "clocks" to assess the biological age of the cells, all of which indicated a similar aging pattern to cells during normal brain development.

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The brain can develop outside the human for longer than we have been able to show so far.