Stanford scientists grow human brain tissue in mice, filling 90% of missing cortex

Stanford scientists have transplanted lab-grown human brain tissue into mice engineered to lack most of their cerebral cortex, with the human tissue expanding to fill over 90 percent of the cortical space and forming working connections. The study, published in Nature on September 16, offers a new model for studying human brain development and diseases. The researchers created "apallial" mice with only about 2 percent of normal cortical tissue, then surgically placed two-month-old human cortical organoids into the brains of two-day-old pups. Within three months, the human neurons integrated with the mouse brain and spinal cord, and behavioral tests showed the mice performed broadly similarly to normal mice, with subtle differences in gait and memory. The model enables studying patient-specific cells, and in a proof-of-concept experiment, human tissue showed vulnerability to oxygen deprivation resembling cerebral palsy aspects. Notably, rare von Economo neurons appeared for the first time in a lab model. The team consulted ethicists and philosophers, with Stanford holding patents on the technology for future research into autism, schizophrenia, and epilepsy.