Mice With Mostly Human Cortical Tissue Could Help Reveal How Brain Disorders Develop

A team from Stanford University has successfully implanted human brain tissue into mice to better understand and study neurological disorders. Ethicists, patient advocates, philosophers, and legal scholars were consulted to address the ethical concerns raised by this groundbreaking experiment. The researchers generated human neurons by growing stem cells into tiny clusters called organoids, which were then transplanted into newborn mice that had a genetic modification causing them to develop without most of their cerebral cortex.

These human cells formed networks that connected to the animal's nervous system and grew to make up over 90% of the mice's cortical tissue within three months. Although the mice could still walk and explore their surroundings, tests showed differences in their paw coordination and movement patterns. The researchers also found that the transplanted tissue displayed signs of injury and inflammation when exposed to low oxygen levels, which affected the mice's walking patterns.

This model provides a unique opportunity to study how disease-associated alterations in human brain circuitry manifest in an intact nervous system, with the long-term goal of investigating disease and testing treatments.