Chinese and French scientists found a potential way using tiny gas bubbles induced by exposure to ultrasonic waves to at once deliver drug and block tumor growth.
In a study published on Tuesday in the journal Applied Physics Letters, scientists from Xi'an Jiaotong University in China and University of Tours in France discovered the dual use of gas embolotherapy, a therapy that cuts off the blood vessels that feed tissue growth by acoustic droplet vaporization (ADV).
ADV uses microscopic gas bubbles induced by exposure to ultrasonic waves, according to the researchers. This method of starving tumors of blood supply and nutrients is less invasive than surgery.
"We have found that gas embolotherapy has great potential to not only starve tumors by shutting off blood flow, but also to be used as a source of targeted drug delivery," said Feng Yi, associate professor of biomedical engineering at Xi'an Jiaotong University and first co-author of the paper.
In gas embolotherapy, researchers inject droplets, from tens to hundreds of nanometers in diameter, into feeder vessels surrounding the tumor and then thanks to the ultrasound, the droplets become gas bubbles that can block feeder vessels like arterioles.
The researchers found that the bubbles not only blocked the arterioles, but other gas bubbles made their way into the capillaries, resulting in vessel rupture.
Researchers tested ex vivo on rat tissue that attaches the intestines to the abdominal wall.
They delivered droplets of dodecafluoropentane containing a bovine serum. With the ultrasound, the bubbles accumulated, sometimes merging, as they lodged themselves in the capillaries.
At one point, the researchers observed a local vessel invagination or a pouchlike cavity, which was caused by the interaction between the bubble and vessel and led to a capillary rupture.
Their findings could provide a one-two punch for cancer treatment: shutting off blood flow from the arterioles and delivering drugs through the capillaries.
In addition, chemotherapy drugs could be kept localized for longer periods of time because blood flow has been shut down, reducing drug dosage.
"In cancer therapy research, scientists are always interested in answering two questions: how to kill the cancer effectively and how to reduce the side effects of chemotherapeutic drugs," said Wan Mingxi, professor of biomedical engineering also at Xi'an Jiaotong University and corresponding author of the paper.
"We have found that gas embolotherapy has the potential to successfully address both of these areas," said Wan.
