Brain organoids, miniature lab-grown models of the human brain’s wrinkled surface, have shown promising results in repairing damaged connections in the brains of rats. In a recent study, published in the journal Cell Stem Cell, researchers demonstrated that human stem cell-grown brain organoids can be transplanted into the visual cortex of rats to repair broken connections in the rodents’ sensory processing systems.
The Process of Transplanting Brain Organoids
The team of researchers grew the organoids from human stem cells and used chemical cues to coax them into 3D clumps that contained many, but not all, of the cell types found in the human cerebral cortex. To transplant each organoid into a rat brain, the team removed a piece of each rodent’s skull, placed the organoid inside, and sealed the hole with a protective cap. The rats received immune-suppressing drugs to prevent their bodies from rejecting the transplant.
Over a period of three months, the rats’ blood vessels infiltrated the organoids, and the organoids’ cells became physically intertwined with the rest of the rodents’ visual processing systems. The organoids grew slightly larger, gained new cells, and extended wires to link to the rats’ brain cells.
Results of the Study
The researchers mapped out the new connections using a fluorescent tracer and revealed that the organoids had successfully connected to the retina through this network of wires. When the researchers showed the rats visual stimuli, including flashing lights and black and white bars on a screen, they found that the organoids activated in response.
Potential for Future Applications
The study authors propose that someday brain organoids could potentially be used to mend the brains of human patients following a traumatic injury, invasive surgery, or stroke, or to help combat the effects of neurodegenerative diseases. However, more research is needed before the technology can be applied to humans. The team is now working on assessments of the rats’ vision and behavioral changes following the transplant and hopes to test the integration of organoids into other parts of the brain in the future. They also aim to improve upon brain organoids to better mimic a real human brain.