The human brain was formed from two distinct organs that merged during evolution hundreds of millions of years ago. Research has shown that the front and back parts of the brain develop from different types of stem cells. This discovery has overturned previous scientific beliefs and, for the first time, made it possible to grow brainstem neurons in laboratory conditions.

Embryonic Brain Development

A team of specialists from Stanford University studied the early stages of embryonic development in mice during the gastrulation phase, when the future tissues of the organism are formed. It was found that the forebrain and hindbrain develop along two independent pathways that do not intersect. The formation of the forebrain and midbrain is associated with cells where the Otx2 genome is active, while the hindbrain develops from cells with the Gbx2 genome. These differences are determined at the chromatin level—the DNA packaging structure that regulates gene accessibility for transcription—and are established from the very beginning of cell development.

Laboratory Cultivation of Neurons

Previous attempts to turn precursor cells of the forebrain into brainstem neurons were unsuccessful. After clarifying the mechanisms of organ development, researchers were able, for the first time, to grow motor nerve cells of the hindbrain in the laboratory. For this, universal human stem cells capable of forming any tissue in the body were used. The neurons obtained in laboratory conditions demonstrated full activity, including the generation of electrical impulses necessary for transmitting signals between nerve cells.

Evolutionary Aspects

Analysis revealed that the dual structure of the brain emerged about 550 million years ago. A similar division has been found in chickens, zebrafish, and hemichordate worms. In jellyfish, two independent nervous systems are located at opposite ends of the body.

Medical Perspectives

This achievement opens new opportunities for studying severe incurable diseases that affect the brainstem, such as amyotrophic lateral sclerosis and spinal muscular atrophy. Additionally, creating hindbrain tissue in the laboratory may contribute to the development of drugs for treating obesity, since this part of the brain controls the sensation of hunger.