A radically different concept of how the brain’s blood supply develops is outlined in a study led by Massachusetts General Hospital researchers.
In experiments with mice, the researchers found that blood vessels in the brain grow according to their own agenda beginning early in fetal development. They also found that the vasculature of an embryo’s brain may actually guide later development of brain cells and their connections.
The findings were published in the journal Nature Neuroscience.
“Until now, it was believed that, as our brains grew and as neuronal connections and nerve fibers formed, blood vessels carrying oxygen and other nutrients grew passively to meet the brain’s metabolic needs,” senior author Pradeep Bhide, director of research for Massachusetts General Hospital Neurology and an associate professor of neurology at Harvard Medical School, said in a prepared statement.
“This new study calls for a complete revision of the model of brain vascular development and places emphasis on genetic mechanisms guiding the proliferation and migration of the cells that make up blood vessels,” Bhide said.
Bhide and his colleagues labeled endothelial cells (building blocks of blood) with fluorescent markers and tracked their movement as they created new blood vessels in the brains of fetal mice. The endothelial cells’ division, migration and assembly of new blood vessels occurred in a highly coordinated and orderly way.
The researchers concluded that the endothelial cells were following their own genetic programs — not those that govern the formation of brain cells — and that the endothelial cells weren’t simply responding to the growing metabolic needs of developing brain tissue.
“In addition, we found that some of the genes that regulate neuronal development also regulate endothelial cell development, which unifies the principles of development of both cell types,” Bhide said. “Our study also finds that endothelial cells in the fetal brain may guide development of neuronal networks and places the embryonic brain’s vasculature in a position to play dual and independent roles of supplying nutrition and carrying instructive signals for brain development.”
These findings may help improve understanding of brain malformations and developmental disorders, the researchers said.
(Source: Massachusetts General Hospital, news release, March 16, 2008)