Growing brains in the lab

During development, the nervous system forms as a flat sheet called the neuroepithelium on the outer layer of the embryo. This sheet eventually folds in on itself to form a neural tube that gives rise to the brain and spinal cord, a process that involves the proliferation and migration of immature nerve cells to form the brain at one end and the spinal cord at the other.
Yoshiki Sasai, Taisuke Kadoshima and colleagues from the RIKEN Center for Developmental Biology have now shown that human embryonic stem (ES) cells can spontaneously organize into the cerebral cortical tissue that forms at the front, or ‘brain’ end, of the developing neural tube1. 
Sasai and his colleagues previously developed a novel cell culture technique that involves growing ES cells in suspension, and have shown that these cells can self-organize into complex three-dimensional structures.
They have already used this method to grow pieces of cerebral cortex and embryonic eyes from mouse ES cells. And more recently, they have shown that human ES cells can also organize into embryonic eyes containing retinal tissue and light-sensitive cells.