Of all the body’s organs, the brain is the most like Area 51: Entry to the region is severely restricted, thanks to a barricade of cells and molecules known collectively as the blood-brain barrier. Increased surveillance by scientists has now pinpointed the barrier’s senior operatives, cells that are tasked with monitoring the razor wire–like barricade that keeps all but a select few from entering the brain.
In two papers published online October 13 in Nature, scientists report that specialized cells called perictyes are crucial in the blood-brain barrier’s development and its maintenance in adulthood. A better understanding of how these pericytes function could help elucidate why some people fare especially poorly after traumatic brain injury or get particular neurological diseases such as cerebral palsy, scientists say. And new research could also lead to tricks for selectively opening or closing the blood-brain barrier, letting in medications that might combat diseases such as Alzheimer’s.
One of the new studies demonstrates that pericytes are necessary for cementing the barrier’s cells into a nearly impenetrable wall surrounding blood vessels in the central nervous system. The work also establishes a timeline: In mice, the blood-brain barrier develops well before birth, researchers from Stanford and the University of California, San Francisco report. Pericytes also appear to keep the barrier’s cells on lockdown, dialing down the activity of genes that, if left to their own devices, would spur the transport of molecules across the barrier and into the brain.
The second new study establishes that pericytes play a key role in regulating the blood-brain barrier in adult mice and also identifies a drug that appears to slow the transport of molecules across a leaky blood-brain barrier. In mutant mice lacking functional pericytes, the leukemia drug imatinib quickly halted the willy-nilly passage of molecules into the brain, researchers from Sweden and Germany report.