Blood bubbles promise new treatments for brain disease

(Image: Eleanor Stride)

SCUBA divers are all too aware of the danger of bubbles of air forming in the blood.  

The bends can be lethal. But bubbles in the bloodstream are not always a bad thing. 

Much smaller bubbles can be used to deliver drugs, help prevent damage from stroke and even open up the blood-brain barrier, a discovery that could lead to new treatments for diseases of the brain.

A few decades ago, researchers discovered by chance that "microbubbles" of air in the blood made ultrasound images clearer and brighter. Now a group of researchers who call themselves "the bubble community" are finding new roles for these bubbles.

Ultrasound applied to microbubbles in the blood causes them to oscillate, which appears to boost the uptake of drugs and gene therapies into nearby cells, though how this works is unclear.

"The theory is that the bubbles are stimulating natural uptake mechanisms," says Eleanor Stride at University College London. "Exactly which mechanisms, we're not sure."

Stride's team has enhanced this effect by adding magnetic nanoparticles to the microbubbles. The group injected mice with a solution containing a gene for bioluminescence, and a suspension of bubbles, before magnetically dragging the bubbles to one lung and applying ultrasound there.

Three days later, the team found bioluminescence only in the target lung, confirming that the gene hadn't been expressed elsewhere. The findings were presented at the Institute of Electrical and Electronics Engineers Ultrasonics Conference in San Diego, California, last month.