The holy grail of cancer chemotherapy is getting a toxic drug to a tumor cell without harming healthy cells, and bubbles within bubbles, based on those already used in medical imaging, could bring this a little closer.
"Chemotherapy can be a frustrating process because you end up ingesting all these really noxious chemicals into the body," Stuart Ibsen of the University of California, San Diego (UCSD), said to Inside Science. "Only a fraction of [them] ever reach the tumor. The rest circulate around the body creating side effects."
To try to get the drugs specifically to the cancer cells, the UCSD team wrapped the drugs in a blood cell-sized vesicle, and then coated this with another layer that stabilizes the bubble and traps a little more drug. The layers are based on ultrasound agents and protect the cells from the toxic effects of the drugs as the bubbles circulate around the body.
The bubbles only break open when they are hit by waves of ultrasound. So by focusing ultrasound just on the tumor, the drugs are only released where they are needed, and the process can be seen using high-tech imaging. An added advantage is the effect on the cells: The ultrasound makes it easier for the cancer drugs to pass across the cell membrane.
This is very early research and will only work on localized tumors in known locations. However, it could be useful to reduce the size of large tumors before surgery, including breast, ovarian, prostate, bladder and lymph node cancers, or where surgery is not a safe option. The next step is to develop a similar system based on nanoparticles, which should last longer in the body.