The side effects of chemotherapy—from pain and hair loss to permanent organ damage—are a result of the fact that the drugs kill healthy cells along with cancerous ones. A dose of toxic chemo goes everywhere in the body. But tiny new nanobots could eventually be used to deliver cancer-fighting drugs only to the tumor sites.
"You can decrease the dose, minimize the systemic toxicity for the patient, and increase the therapeutic effect of any type of therapeutic agent," says Sylvain Martel, director of the Polytechnique Montreal Nanorobotics Laboratory, one of the researchers working on the new technology.
Right now, because cancer drugs passively drift through the body, only 1-2% usually ends up at an actual tumor. Most of the treatment is wasted—and even worse, most of it ends up killing healthy cells. Cancer treatments become both more painful and more expensive, because patients are likely to end up in the hospital with side effects.
The new system uses bacteria that are naturally drawn to low-oxygen areas, the parts of a tumor that are currently hardest to treat. The bacteria are guided by a magnetic field. "In the natural environment, this bacteria synthesizes a chain of nanoparticles that's like a microscopic compass needle," says Martel.
In the lab, the researchers used a weak magnetic field to guide the bacteria toward the tumor. Once they arrive, the bacteria start using their own natural navigation system to locate low-oxygen areas—parts of the tumor that are often missed by traditional treatments now, and can end up spreading throughout the body months or years later.
In about half an hour, the bacteria dies and releases the drug exactly where it's needed. The bacteria can go deep into tumors because they are naturally strong swimmers. "The best Olympic swimmers can swim about one body length per second," says Martel. "These go 200 body lengths a second, even 300. They go very fast, against strong pressure, and they go deep."
The bacteria also happen to be the perfect size—a tiny one to two microns—to slip inside the two-micron-sized holes in blood vessels in a tumor. All the researchers had to do was load them with the medicine, and the bacteria naturally take care of almost everything else, like power and navigation.
While some others are working on artificial nanobots that would deliver drugs in a similar way, the bacteria can reportedly do a better job than the best technology now. "It's not as effective as billions of years of evolution," he says. "The technology is not there. They have some results, but it's missing the power source, the sensors, the onboard computer, all of those things."
The bacteria works in mice; one of the next steps will be proving it's safe to use in humans.
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