Stanford study finds human brain develops from two separate embryonic progenitors
Researchers at Stanford Medicine reported that the forebrain and hindbrain arise from distinct progenitor cells, a finding that could improve laboratory models of brain-stem diseases.
Scientists at Stanford Medicine have shown that the human brain originates from two independent embryonic cell lineages rather than a single progenitor. The study, published in Nature Neuroscience, identified one progenitor expressing the gene Otx2 that gives rise to the forebrain and midbrain, and a second expressing Gbx2 that forms the hindbrain. The two cell populations remain mutually exclusive from the earliest stages of development, and their chromatin configurations differ markedly, locking each lineage into its specific fate.
"We've shown for the first time that the front of the brain arises from a totally different progenitor cell than the back of the brain," said Kyle Loh, associate professor of developmental biology and senior author of the paper. The researchers also demonstrated that human pluripotent stem cells can be directed to become functional hindbrain motor neurons, which display characteristic electrical activity and protein markers.
The discovery may explain longstanding difficulties in generating hindbrain neurons in vitro and opens new avenues for studying disorders that affect the brain stem, such as spinal muscular atrophy and amyotrophic lateral sclerosis. By providing a reliable source of hindbrain cells, the work could facilitate drug testing and the investigation of disease mechanisms.
Comparative analysis of embryos from chickens, zebrafish and acorn worms revealed a similar dual-origin pattern, suggesting that the split brain architecture dates back over 500 million years. The authors propose that evolution combined two pre-existing neural systems into the single organ we now call the brain.