Blobs of human brain tissue have been [1]transplanted into the brains of rats in work that could pave the way for new treatments for devastating brain injuries. The Guardian reports:

> The groundbreaking study showed that the "human brain organoids" -- sesame seed-sized balls of neurons -- were able to integrate into the rat brain, linking up with their blood supplies and communicating with the rat neurons. The team behind the work suggest that eventually doctors might be able to grow blobs of brain tissue from a patient's own cells in the lab and use them to repair brain injuries caused by stroke or trauma.

>

> Chen and colleagues grew human brain organoids in a dish until they were about 1.5mm in diameter. The balls of tissue were then transplanted into the brains of adult rats that had sustained injuries to their visual cortex. Within three months, the grafted organoids had integrated with their host's brain, hooking up with the blood supply, expanding to several times the initial volume and sending out projections that linked up with the rat's neurons, according to the study [2]published in Cell Stem Cell . The scientists did not assess whether the implants improved how well the rats were able to function, but tests showed that the human neurons fired off electrical signals when the rats were exposed to flashing lights.



[1] https://www.theguardian.com/science/2023/feb/03/blobs-of-human-brain-planted-in-rats-offer-new-treatment-hope

[2] https://www.cell.com/cell-stem-cell/fulltext/S1934-5909(23)00004-8