Scientists Grew Human Brain Tissue Inside Mice, And It Connected to Their Nervous Systems

Dorsal views of mouse brains showing control, apallial and human-organoid-engrafted (XCX) mice. The XCX mice developed extensive human-derived cortical tissue following transplantation of human cortical organoids.
Image: Kaganovsky et al., Nature (2026).

Scientists have managed to make human brain matter grow inside mice and found that the new nerve cells form connections with the mice's own nervous system.

The findings were published in a research paper in the journal Nature on 16 September 2026, describing how scientists took human cells and produced cortical organoids from them that were placed in newborn mice whose cerebral cortex had been genetically depleted during development.

This experiment produced some interesting results. After three months, the human-derived tissue accounted for 91.9% of the combined cortical tissue volume in the experimental mice examined. Researchers found different types of human nerve cells, as well as signs of neuronal activity and connections between these human cells and the mouse nervous system.

This does not mean the mice acquired a human mind. The researchers measured things such as neural development, brain activity, connectivity and behaviour. They did not establish whether the animals had anything resembling human consciousness or thoughts.

The mice were broadly functional, although researchers found differences in limb coordination and the organisation of spontaneous behaviour. In another experiment, low-oxygen exposure caused substantial damage to the human-derived tissue and was associated with problems maintaining gait and balance.

What I find the most interesting about this type of experiment is that it did not create a “human-mouse brain”. Instead, it created a living environment where human cortical tissue could develop and connect with an existing nervous system.

The researchers suggest the model could help scientists study human brain development and neurological disorders, although those potential applications are still research possibilities rather than established treatments.

Source:

Nature: Developmental xenocortication using human-derived organoids in mice (16 September 2026)