Holy magnetic bacteria, Batman! Researchers at the Polytechnique Montreal NanoRobotics Laboratory want to use magnetic bacteria to traffic drugs to tumors.
First of all, magnetic bacteria
? Yes, they’re a real thing. Magnetococcus marinus
is a bacterium that lives deep down in the ocean where oxygen is scarce. Magnetococcus
contains a magnetosome
- a structure that contains between 15 and 20 magnetite crystals. These magnetic crystals act like a tiny compass that orients the cell with the Earth’s magnetic field. Odd thing is, these magnets also help the bacteria find environments with very little oxygen (that’s a topic for another time).
So, what do magnetic bacteria that like hypoxic environments have to do with cancer? One problem with systemic cancer therapy is that it’s systemic. If a cancer drug isn’t targeted specifically to the cancer, healthy cells also suffer (and that’s not good). To solve that, researchers are developing so-called nanocarriers to deliver drugs specifically to tumors. The problem is, however, that the nanocarriers have trouble making it to the inside of a tumor. Incidentally, the inside of a tumor is usually hypoxic. Magnetic bacteria to the rescue!
The idea is that a magnetic field can be generated to direct the bacteria to the tumor. Then, it’s up to the bacteria to find their way into the hypoxic zone of the tumor. I should also mention - vesicles containing cancer drugs would be attached to the bacteria.
According to study author Sylvain Martel, “
When they get inside the tumor, we switch off the magnetic field and the bacteria automatically rely on [their] oxygen sensors to seek out the hypoxic areas. We constrain them to the tumor and then let nature do the rest.”
As proof-of-concept, Martel and colleagues tested this system in mice afflicted with human colorectal tumors. First, they wanted to know whether the bacteria could traffic to and penetrate a tumor. They injected mice with live bacteria, dead bacteria, or non-magnetic beads. Very few dead bacteria or non-magnetic beads made their way into the tumors, but a significant number of live bacteria did.
Next, they attached drug-loaded vesicles to the bacteria (around 70 vesicles per bacterium) to see how this would affect their movement into the tumors. They found that roughly 55% of the vesicle-loaded bacteria penetrated the tumors. That’s huge, considering only around 2% of nanocarriers are delivered to tumors!
But wait, are you wondering if it’s a good idea to inject live bacteria into live people? Well, Magnetococcus is not a pathogen, and the researchers insist that they only survive for about 30 minutes after injection.
Source: National Institute of Biomedical Imaging and Bioengineering