Stanford ‘alien-cortical’ mice carry lab-grown human neurons in the brain
Researchers at Stanford University have implanted lab-grown human cells into mice born without most of the cerebral cortex and neighbouring hippocampus, according to a Nature study of “alien-cortical mice.” The aim is to study neural circuits and disorders such as schizophrenia, cerebral palsy and dementia. At two days old, the animals received organoids grown from healthy donors’ stem cells, each holding about 100,000 human cells. They removed about 14 million mouse neurons and added about 4 million human ones, and said this is not a brain transplant and the mice do not think like humans.
The method worked in 25 of 29 mice. Within three months the tissue grew about five times larger, linked to the blood supply and filled more than 90 percent of the cavities, roughly half of brain volume; the mice walked and vocalised mostly normally. Mice without implants got lost in a maze, while those with human cells did better. Some tissue formed von Economo neurons, rare cells absent in mice and found in humans, apes, whales and elephants. Low oxygen brought brain damage, an altered gait and poor limb coordination. Senior author Sergiu Pasca, professor of psychiatry and behavioural sciences at Stanford, said this will not replace earlier models but can access human brain functions otherwise hard to study. Experiments stopped when the implanted human nerve cells were six months old, before they could form more neural connections with the animals’ brains.
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