New York, Jun 29 (IANS): A special protein found in the brain's tiniest blood vessels may increase the risk of stroke, find researchers.

The protein called FoxF2 is found in the brain's smallest blood vessels called capillaries and are essential for the development of the blood-brain barrier.

In a study done on mice, the team found how the blood-brain barrier develops and what makes the capillaries in the brain different from small blood vessels in other organs.

"Mice that have too little or too much FoxF2 develop various types of defects in the brain's blood vessels," said Peter Carlsson, professor at the University of Gothenburg's department of chemistry and molecular biology.

The brain's smallest blood vessels differ from those in other organs in that the capillary walls are much more compact.

The nerve cells in the brain get the nutrients they need by molecules actively being transported from the blood, instead of passively leaking out from the blood vessels.

This blood-brain barrier is vital, because it imposes strict control over the substances with which the brain's nerve cells come into contact.

"It has a protective function that, if it fails, increases the risk of stroke and other complications," the authors noted.

The FoxF2 gene is an extremely interesting candidate.

"The research is now underway in collaboration with clinical geneticists to investigate the extent to which variations in the FoxF2 gene affect people's risk of suffering a stroke," Carlsson said.

The findings appeared in the journal Developmental Cell.