Human Brain Tissue Transplant Did Not Make Mice Smarter

Scientists at Stanford University grew small pieces of human neural tissue known as organoids and transplanted them into mice whose cerebral cortex had not fully developed.

The transplanted tissue integrated into the new body and increased in size almost fivefold. It occupied more than 90% of the mice’s cerebral cortex. Human neurons also formed connections with the mice’s nervous system, while the rodents’ blood vessels began supplying the new tissue with blood.

However, the transplantation of human brain tissue did not make the mice smarter. In memory tests, the “hybrid” mice showed no significant difference from ordinary mice and achieved similar results.

The human brain develops over many years, while the transplanted tissue reached only the developmental stage of the fetal cerebral cortex during the second trimester of pregnancy after six months.

According to the scientists, this method cannot be used to create a “super mouse.” Moreover, that was not the main goal of the experiment.