The tiny weapon comes from an innate immune cell in our blood vessels, which specializes in detecting and fighting not only viruses, but also certain forms of cancer.
These special immune cells are called natural killer cells (NK) by scientists. They contain small, fatty vesicles full of toxic proteins that can attach to cancer cells. And that turned out to have a powerful effect in the laboratory.
“These are the most striking results I’ve ever seen, and I’ve been doing this work for 25 years,” Marit Inngjerdingen says to Science in Pictures. Inngjerdingen is a professor at Oslo University Hospital and one of the authors of the vesicle study recently published in the scientific journal Frontiers in Immunology.
Growing an arsenal of weapons
Marit Inngjerdingen and her colleagues have discovered that they can grow natural killer cells in the special red liquid in the lab, and then harvest the small, poison-filled vesicles by centrifuging the liquid, causing the fat vesicles to sink to the bottom.
In this way, they can easily and effectively build up a large arsenal of fatty vesicles, which kill clumps of cancer cells grown by the researchers in just 18 hours.
‘About 80 percent of the cancers we tested die. Whether it concerns brain cancer or colorectal cancer, the vesicles attack a wide range of cancer cells,’ says Inngjerdingen.
New kind of immunotherapy
The beauty of the vesicles is that they are already part of the body’s natural line of defense and are therefore not toxic to our healthy cells. That is why Marit Inngjerdingen and the rest of the team hope to be able to use the discovery to create a new kind of immunotherapy against cancer.
‘Only 20 to 30 percent of cancer patients respond to current types of immunotherapy, so there is an urgent need for other types of treatment,’ she explains.
“This is a new way of tackling the cancer cells, and it’s important to have a wide range of treatments so that we can find the right one for each patient.”
The next step for Inngjerdingen and the rest of the team is to test whether the lab-grown vesicles can detect the cancer cells when injected into the bloodstream of a living being. Experimental mice are used for this, in which cancer cells have been introduced under the skin.
If we succeed in shrinking the tumors in the mice, we can expect the first trials in humans within a few years, according to the professor.
“If all goes well, we might be able to start the first human trials in a few years,” she says.
Although she and her colleagues are still in the early stages of understanding why the tiny vesicles target some cancer cells and not others, she already thinks the natural toxins have “huge potential.”
‘They are effective, very easy to make in large quantities, very stable and easy to freeze. And we can attach things to them, kind of like a piece of Lego, so we can tailor them to target specific types of cancer,” she says.