Researchers have discovered a novel and potentially efficient method to deliver drugs to the target cancer tissues using a type of magnetic bacteria known as Magnetococcus marinus.

Drugs used to treat cancer are more potent in nature but cause toxic effects when exposed to healthy cells in the body. In order to deliver the super-potent drugs only to the cancer tissues, researchers have developed nanoparticles packed with drug.

Though the nanoparticles were efficient in sparing the healthy cells while delivering the drugs to the target tissues, the amount of drug that reached the tumor was relatively low. Two main reasons for the shortcoming were that nanoparticles are filtered in the body before they reach the target cells through circulation and that they are unable to enter the hypoxic zones, the most active regions of tumor.

While trying to develop robotic nano-carriers to overcome the constraint, a team led by Sylvain Martel, director of the Polytechnique Montréal NanoRobotics Laboratory, found that the M. marinus bacteria that live in oxygen-deprived zones in oceans. The bacteria use a two-part navigation system to reach such areas in the ocean. The system includes magnetic nano-crystals present within the cells like magnetic compass and special sensors that help in finding low-oxygen zones.

In the study published in the journal Nature Nanotechnology, the researchers reported their experiment with M. marinus in three groups of mice that were made to develop human colorectal tumors. Each group was injected with one of the three different components including live M. marinus, dead M. marinus and non-magnetic beads that act as control.

The injection was made close to the cancer site and directed by a computer-programmed magnetic field to help the bacteria reach the tumor. It was observed on examination that the live bacterial cells made their way deep into the hypoxic zones, while the dead and non-magnetic beads showed minimal penetration.

"When they get inside the tumor, we switch off the magnetic field and the bacteria automatically rely on the oxygen sensors to seek out the hypoxic areas," says Martel. "We constrain them to the tumor and then let nature do the rest."

The researchers then tested the drug carrying efficiency of the bacteria into the cancer cells by attaching 70 drug-packed vesicles to each bacterial cell. It was found that on average 55 percent of bacteria carrying the vesicles reached the tumor cells.

Martel noted on the findings that M. marinus show promise in the treatment of cancer as perfect drug delivery vehicles. He also added that they are cheap to produce and safe because they die within 30 minutes once injected into the host.

Photo: John Voo | Flickr