Karolinska: Key to blood-brain barrier opens way for treating Alzheimer’s and stroke

The blood-brain barrier (BBB) protects the brain from harmful proteins in the blood, but it also obstructs the transport of drugs to the brain. Now scientists at Karolinska Institutet and the Sahlgrenska Academy in Gothenburg have come up with a potential solution to the problem.

The key to the BBB is a cell-type in the blood vessel walls called pericytes. Christer Betsholtz, professor of vascular biology at the Department of Medical Biochemistry at the Karolinska, who led the study, said, “Our new results show that the blood-brain barrier is regulated by pericytes, and can be opened in a way that allows the passage of molecules of different sizes, while keeping the brain’s basic functions operating properly.”

Betsholtz says this new understanding of how the BBB is regulated could be used in two ways. “To protect the brain under conditions, such as stroke and inflammation that lead to the opening of the BBB and the release of damaging substances, and to open the barrier temporarily to allow the transport of drugs against neurodegenerative and other diseases into the brain.”

The research shows how this would be possible. The pericytes normally maintain the barrier function through an as-yet unknown molecular mechanism; in their absence, a process called transcytosis opens a path through the capillary walls so that molecules of different sizes, including large plasma proteins, can pass from the blood into the brain. The pericytes also regulate astrocytes, another type of brain cell, which also contribute to the BBB.

References

Pericytes regulate the blood-brain barrier
Armulik, A. et al.
Nature advance online publication 13 October 2010
http://dx.doi.org/10.1038/nature09522