Human neurons integrated into cortex‑deficient mice create chimeric model for brain disease research

Scientists engineered mice that lack most of their cerebral cortex and grafted roughly four million cultured human cortical neurons into the empty regions. The human cells expanded, became vascularized and formed connections that reached the spinal cord, and the resulting chimeric cortex was reported as predominantly human in volume, including rare neuron types such as von Economo cells. Mice showed partial restoration of functions that were impaired by the cortical deficit and reacted to oxygen deprivation in ways that resembled human responses. The work is being conducted under ethical oversight, with researchers stopping the experiments before the human cells reached six months of development.