Why you should care
Because a tiny sea organism’s race to the North Pole may hold the key to diagnosing and fighting cancer.
The North Pole has never been hotter — and not just because of global warming. U.S. Representatives Jim Sensenbrenner and Rick Larsen both want to launch an ambassadorship to the Arctic, while Canada, Denmark and other countries are racing to claim sovereignty over the region. And at the end of this year, extreme endurance enthusiasts will test their limits in the ninth annual North Pole Marathon — the “World’s Coolest Marathon.”
But some organisms have set their sights on the North Pole for much longer, swimming toward the frigid clime to survive. Scientists have taken a cue from so-called magnetotactic bacteria (MTB) and their natural, built-in magnetic compasses as a strategy to help human patients survive — even fight cancer.
Researchers are especially excited about using these nanocrystals for a cancer therapy known as magnetic hyperthermia.
The Earth is like a big magnet due to its molten iron core. About 50 years ago, scientists first reported the existence of aquatic MTB, whose tiny compasses sense Earth’s magnetic field, helping them navigate waters to find the environments where they’ll thrive. We now know that these MTB assemble their compasses from microscopic structures called magnetosomes, which contain nanosized crystals of iron-embedded magnetite, the most magnetic mineral found in nature.
Researchers are especially excited about using these nanocrystals for a cancer therapy known as magnetic hyperthermia. Once they reach their target cell, a magnetic field can be applied to the nanocrystals, causing them to heat up and eventually destroy the cell — with zero side effects. How can these nanoparticles reach their destination? One way is to bind them to killer cells, immune cells that naturally target tumor cells.
But MTB’s extreme aversion to oxygen can make isolating and cultivating them tricky. Large-scale commercialization requires researchers to efficiently grow MTB or produce the magnetosomes in another organism. In a recent Nature Nanotechnology study, scientists chose the latter, genetically engineering an easier-to-handle bacterial species — the first report of manipulating an organism to sense magnetic fields.
To limit the amount of nanoparticles used, it’s crucial for the magnetic nanoparticles to absorb heat efficiently. Bacterial nanoparticles do just that. Magnetosomes in MTB naturally assemble into tightly packed, ordered chains to form strong magnets. As a result, we only need a tiny amount of heat and nanoparticles to heat a tumor cell in a magnetic field. A French company called Nanobacterie has shown that applying a magnetic field to breast cancer cells containing just one milligram of MTB-derived magnetosomes completely destroys tumors in mice. A third possibility for manufacturing magnetic nanoparticles is to chemically synthesize them, like New York-based company Nanoprobes.
A French company has shown that applying a magnetic field to breast cancer cells containing just one milligram … completely destroys tumors in mice.
One company has already made the leap to bring magnetic nanoparticles to the clinic. Germany’s MagForce AG, the first company in the world to receive European approval for a medical product using magnetic nanoparticles, started patient enrollment in the first quarter of 2014 to further validate NanoTherm therapy, which uses a magnetic hyperthermia approach, against the most common and aggressive primary brain tumor. Just one milliliter of the company’s magnetic liquid NanoTherm harbors quadrillions of metal nanoparticles.
Meanwhile, NanoTherm’s coating causes nanoparticles to come together and remain inside the cells upon injection, allowing for repeated treatment. Magforce AG also met with the FDA in the first quarter of 2014 to discuss registering NanoTherm therapy in the U.S.
Besides cancer therapy, magnetic nanocrystals can also improve patient diagnosis. Fluorescent dyes fused to magnetic nanoparticles can help physicians to better distinguish between healthy and diseased tissue in MRI scans. Studies also show that stem cell therapy can be monitored using transplanted stem cells labeled with magnetic FDA-approved nanoparticles.
The possibilities for MTB are as vast as the Arctic tundra. Since magnetic nanoparticles are often used in data storage, magnetic nanocrystals could be used to build smaller but more robust hard drives as tech gadgets get smaller. Aquatic MTB might also be able to detect and remove toxic heavy metals from wastewater by magnetic separation. And on the flip side, metal nanoparticles could be used to recover precious metals.
Regardless of the venture, learning and mimicking the energy-efficient route of making magnetic nanoparticles, thanks to a tiny organism’s race to the North Pole, has already opened countless doors and will probably continue to do so.