It's the stuff of gothic horror novels: growing a brain in a laboratory.
The human brain is evolution's most complex creation--86 billion neurons wired together. Studying it has always been neuroscience's greatest challenge. Animal models provide insights, but mouse brains aren't human brains. And the only human brains available are dead ones, whose tissue reveals structure but not function. Living human subjects are, of course, off limits. Can't do invasive experiments on live human brains.
If it was possible to grow a convincing brain in the lab, neuroscientists would make good use of the opportunity. Organized, three-dimensional structures that faithfully recreate the intricate architecture of the human cortex would be an invaluable window into the black box of brain development. A home-grown brain would offer scientists a testing ground for neurological drugs, and a path to understanding devastating conditions like autism, schizophrenia, and Alzheimer's disease. Of course, this was for years just a far-fetched fantasy, possible only in Frankenstein stories.
Until now.
They're called brain organoids -- literally "mini-brains". And they are very real. These cerebral organoids, derived from human stem cells, promise to offer science a live brain worthy of study.
They were first developed in 2013 by the true Dr. Frankenstein of our era, Madeline Lancaster and her colleagues at the Institute of Molecular Biotechnology (IMBA) in Vienna, Austria. She grew the first brain. Or something close enough.
Their groundbreaking work demonstrated that human stem cells could self-organize into three-dimensional structures that resembled developing brain tissue. These early organoids displayed distinct brain regions and layered organization similar to the developing human cortex, complete with different types of neurons and support cells. They offer something unprecedented: actual human brain tissue that can be observed, manipulated, and tested in ways impossible with living subjects.
Suddenly it was possible for researchers to watch in real-time as genetic mutations derailed brain development. They could test thousands of drug candidates without risking human lives. They could unravel the biological mechanisms behind psychiatric disorders that have resisted understanding for centuries.
There was just one problem. And it threatened to end the project: the organoids kept fusing together. When multiple brain organoids were cultured together in suspension -- which is how they're grown -- they would spontaneously stick together and fuse. This resulted in inconsistent structures of wildly different sizes. That made controlled experiments impossible. Researchers had to manually separate them constantly, a time-intensive process that limited experiments to small batches. Scaling up was a fantasy.
In a paper published this June, Stanford researchers announced a solution. And it involves the same thickening agent found in Ranch dressing. It's called xanthan gum, and when added to the culture medium, it created a microenvironment where organoids could grow in close proximity without sticking together.
Seems like a simple thing, keeping the brains apart. But the results were transformative. Because they could grow a lot of them.
The researchers cultured over 2,400 cortical organoids and screened 298 FDA-approved drugs and known teratogens--all managed by a single researcher. The organoids maintained proper brain-like structures, with neural progenitor cells and appropriate regional markers. They grew uniformly, making comparisons meaningful. The xanthan gum caused no toxicity and didn't interfere with normal brain development patterns.
It was a revolution in brain research.
The implications for medical science are staggering. This platform transforms brain organoid research from boutique science to industrial-scale investigation. Thousands of drug candidates can now be screened simultaneously for neurotoxicity. Genetic variations linked to autism or schizophrenia can be tested across hundreds of organoids to understand which changes truly matter. Environmental toxins can be evaluated for their impact on developing brains. Dangerous pharmaceuticals can be uncovered before ever reaching human trials.
The pace of neuroscience discovery could accelerate exponentially.
But here's the unsettling question science has yet to face. What happens when these mini brains become aware? When the neural tissue that mimics the human brain crosses that line, and gains consciousness?
The Stanford paper describes enabling one researcher to maintain over 2,000 cortical organoids simultaneously. What if there is an undetected emergence of consciousness on a mass scale? There are no checkpoints in place.
In the study described by the paper, organoids were exposed to 298 different drugs, some that are known to be dangerous. Was anything experienced by these thousands of brains? Was there distress caused without the ability to call for help?
We don't think so. At least, not yet.
There's no scientific evidence that current organoids have any form of consciousness, awareness, or subjective experience. But we don't know at what point, as these things develop, some outward communication might become possible. We're measuring activity in the organoids, but we have no way to know if there's any "experience" behind it.
We agree it is unethical -- even unimaginable -- to experiment on live human brains. The question is: have we just created a way to do just that on an industrial scale? And what happens when the thousands of brain organoids decide they're done with the experiment?