Stanford Study Identifies Two Distinct Embryonic Origins for the Human Brain

Key points

• Researchers found that the forebrain/midbrain and hindbrain arise from distinct progenitor cells during embryonic gastrulation.
• The hindbrain, which controls vital functions like breathing and swallowing, develops from cells expressing the Gbx2 gene, while the forebrain/midbrain comes from Otx2-expressing cells.
• These two cell types have fundamentally different chromatin structures, making it impossible to convert one into the other in a lab setting.
• The discovery allows scientists to successfully grow hindbrain motor neurons from human pluripotent stem cells for the first time.
• This finding may lead to better treatments for spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), which affect hindbrain neurons.

Background

This finding builds on recent Stanford research into brain development, including studies on grafting human brain tissue into mice to model neurological disorders. The new study challenges the long-held belief that the brain develops from a single progenitor cell, instead proposing a dual-origin model that has been conserved for over 550 million years.

How outlets are covering it

While TechSpot and Stanford Medicine emphasize the 'two organs' framing, Ars Technica argues this is a misleading oversimplification. Ars Technica notes that while the hindbrain and forebrain/midbrain have distinct developmental fates, they are part of a single contiguous organ. The Nature article, the primary source, focuses on the lineage tracing and chromatin differences that support the dual-progenitor model. All sources agree on the practical implications for growing hindbrain neurons and treating diseases like ALS and SMA.

Why it matters

This discovery explains decades of failure to grow hindbrain neurons in labs and opens new avenues for studying and treating devastating neurological diseases that affect the brain stem, such as SMA and ALS. It also provides a new model for understanding how the brain develops and could lead to regenerative therapies.

What to watch

Researchers plan to extend their studies to determine the developmental origins of the spinal cord and to learn exactly how SMA and ALS compromise the function of hindbrain neurons. They hope to use the new model to develop regenerative therapies for these diseases.