Ultrasound and microbubbles improve chemotherapy delivery

A variety of nanoparticle systems have been developed, consisting of small drug-loaded particles that increase the accumulation of a drug in a tumor and reduce its effects on healthy tissues. One approach to further increase the specificity and effectiveness of nanoparticles is to use an external signal to activate drug release on-demand.

One such signal is ultrasound, and nanoparticle/ultrasound combinations for cancer treatment have been featured on Medgadget before. However, this latest attempt has been very successful when tested in mice with an aggressive form of breast cancer.

The Norwegian team encapsulated a chemotherapeutic drug into nanoparticles, and then incorporated the nanoparticles into the surface of small bubbles, called microbubbles. When the researchers injected the microbubbles into the blood stream in mice, and then stimulated their tumors using ultrasound, the bubbles burst, releasing the nanoparticles into the tumor.

Vibrations from the ultrasound make the blood vessels in the tumor more porous. This helps push the nanoparticles further into the tumor, helping them to reach cells further away from the blood vessels.

“By using ultrasound to transport the chemotherapy-laden nanoparticles into the tumors, our research on mice has shown that we can deliver about 250 times more of the drug to the tumor compared to just injecting chemotherapy into the bloodstream alone,” says Sofie Snipstad, a researcher involved in the study.

Using the technique, the researchers appear to have killed the cancer completely in several mice, as their tumors disappeared and didn’t return. “This is an exciting technology that has shown very promising results,” says Snipstad. “That the first results from our tests in mice are so good, and that the medicine does such a good job right from the start is very promising.”