Human brain tissue blobs have been implanted into the brains of rats in research that could open the path for novel therapies for serious brain injuries.

The landmark study demonstrated that "human brain organoids," which are sesame seed-sized balls of neurons, could integrate into the rat brain, connecting to blood supplies and communicating with rat neurons.

The researchers believe that in the future, doctors may be able to create blobs of brain tissue in the lab from a patient's own cells and utilize them to repair brain lesions caused by stroke or trauma.

The research is the most recent in the rapidly expanding and morally challenging field of brain organoids. Scientists have demonstrated that when neurons are cultured under the appropriate conditions, they begin to form miniature brain-like structures, allowing them to explore developmental diseases such as autism and a wide range of basic neuroscience topics.

The new study is the first to show that lab-grown brain tissue can be successfully implanted into an injury location to repair an adult brain, implying that future clinical uses are possible.

Isaac Chen, a physician and assistant professor of neurosurgery at the University of Pennsylvania said, "We were not expecting to see this degree of functional integration so early.”

The scientists did not analyze whether the implants improved the rats' ability to operate, but studies revealed that when the rodents were subjected to flashing lights, the human neurons emitted electrical impulses. This, according to Chen, supports the idea that organoids could serve as "blank processing units" that the brain could absorb and employ to repair itself after injury.

Personalized brain organoids could theoretically be made in the lab using a patient's own cells, but Chen projected that therapeutic applications would be at least five to ten years away. "We are only at the beginning of this adventure," he explained.