Scientists have grown tiny human brains in space to research new treatments for Alzheimer's, Parkinson's and spinal injuries.
The low gravity environment on the International Space Station (ISS) enabled researchers to grow brain organoids in just 72 hours. This process can take months on Earth.
The organoids, which are artificially-grown masses of cells that mimic the structure and function of a human organ, allowed researchers to test a new method for curing currently untreatable neurological diseases.
The promising new treatment, developed by biotechnology company Axonis Therapeutics, uses a reprogrammed virus to deliver beneficial gene therapy to central nervous system cells (CNS).
Such modified viruses are called viral vectors, and they could be particularly useful for treating Alzheimer's, Parkinson's and spinal cord injuries.
Nearly 600,000 Americans are diagnosed with either Alzheimer's or Parkinson's each year, and roughly 18,000 new spinal cord injuries occur in the US annually.
Testing revealed that the company's treatment worked in mice. But gene therapies that are effective in rodent models often fail in humans.
Axionis Therapeutics needed to perform tests using an accurate model of the human central nervous system, which is what prompted them to try and grow human brain organoids in space.
Scientists can grow CNS cells on Earth, but gravity forces them to arrange themselves into two-dimensional single layers, which makes it difficult to culture the three-dimensional structure and complexity of brain cell functional groups.
These space-grown organoids quickly provided a highly accurate model of the human brain, allowing the ISS researchers to truly test the effectiveness of the new viral vector treatment.
'Doing research in space is not something you'd ever think about normally,' said Shane Hegarty, co-founder and chief scientific officer of Axonis Therapeutics.
'But the opportunity to leverage microgravity conditions can unlock a lot of untouched potential by pushing the boundaries of science in a unique environment,' he added in a statement.
In August 2023, Axonis Therapeutics launched frozen vials of their viral vector, mature neurons and astrocytes - or cells that hold nerve cells in place and help them develop - toward the ISS aboard a cargo resupply mission.
A crew of researchers on the floating laboratory then injected these materials into a machine called BioCell, which is a specialized cell-culturing system.
They loaded the viral vector with a fluorescent protein gene. If it successfully infiltrated the neurons and implanted the gene inside them, they would glow neon green.
Within just 72 hours, the cells had not only organized themselves into three-dimensional human brain organoids, but were also glowing.
'The pivotal day was when the crew was doing the microscopy, and we saw big aggregates of green, glowing 3D tissue,' said researcher Sheila Nielsen of BioServe Space Technologies, the research organization that created BioCell.
'Shane and I were sending images of the organoids back and forth to each other, and we were pretty ecstatic because this is not something they had ever seen on the ground,' she added in the statement.
Viruses are very efficient at infecting cells and inserting genetic material into them.
This is how they sicken their hosts - the inserted genetic material damages cells and allows the virus to reproduce, eliciting an immune response.
But scientists can reprogram viruses to carry beneficial gene therapies to cells, providing a targeted treatment for disease or injury.
This study demonstrated that Axonis Therapeutics' viral vector would be able to deliver gene therapy to human neurons.
'It was very exciting - we were able to both validate the gene therapy targeting ability and show that we indeed rapidly formed 3D assembloid models of the human brain,' Hegarty said.
'The major breakthrough is that you can self-assemble mature neurons and astrocytes rapidly into a model of the brain in microgravity conditions, which you can't do on the ground.'
