Cancer is far from pleasant, and unfortunately, one of its common treatments -- chemotherapy -- further burdens patients with its toxic side effects. Researchers have been experimenting with nanoparticles to directly and precisely deliver drugs to tumors, but so far even the best nanoparticles have conveyed only 1% of the drug.
Now, researchers have developed a new approach with nanoparticles that administers 40 times more of the drug to attack the tumor.
The new method uses two teams of particles -- the first to scout out the tumor, and the second to deliver the drug.
In their experiments with mice, tumors treated this way stopped growing, whereas those treated with one type of nanoparticle continued to grow.
Using the body's own know-how
The scientists, who published their study in Nature Materials, got the two groups of nanoparticles to communicate by doing something novel: they harnessed the body's own blood-clotting system.
When the body detects injury to a blood vessel, it sets off a chain reaction that eventually results in the body producing strands of the protein fibrin, which seals the injury and stops blood loss.
In order to piggyback on the communication that happens in that chain reaction, the researchers used two kinds of nanoparticles -- signaling and receiving.
The signaling particles, used in the first wave, enter the tumor. They then make the body believe that an injury has occurred there, sparking the blood-clotting chain reaction. (These particles used one of two methods to trick the body into thinking it is injured: by emitting heat or by binding to a protein that triggers the blood-clotting cascade.)
The second wave of nanoparticles, the receiving ones, are coated with proteins that attract them to the site of the blood-clotting. When they arrive, they bind to the fibrin, simultaneously delivering the drug right to the tumor.
This Nature News story quotes one of the authors, Omid Farokhzad at the Brigham and Women's Hospital in Boston, Massachusetts:
"What's new here is that the system triggers the body to create an environment that favours the accumulation of nanoparticles."
This research is in the early stages and will need more work before it can be applied. In order to be used in clinical trials and gain regulatory approval, the researchers are now exploring ways to to use existing cancer drugs in this cooperative nanosystem.
Another challenge will be to limit the particles to triggering blood clots only in tumors. Cancer patients are prone to blood-clotting elsewhere in the body. The Nature News article quotes Anil Sood, an oncologist at the MD Anderson Cancer Center in Houston:
"If you're going to trigger coagulation, you want to be very selective, so that you don't cause damage in other parts of the body."
via Nature News
Photo: GE Healthcare