Tiny blisters seep out of nearly every cell in the body. Research suggests they are important for a number of diseases, such as cancer and autoimmune disorders.
The tiny vesicles contain information. This can be used for both diagnoses and medicines.(Image: Meletios Verras / Shutterstock / NTB)
Ingrid SpildeIngridSpildeIngrid Spildejournalist
Published
At first, we thought it was just rubbish.
Decades ago, researchers discovered that nearly all types of cells release exosomes – tiny vesicles filled with proteins and other substances.
Because some of their contents appeared damaged or redundant, researchers assumed vesicles were simply tiny garbage bags.
How wrong they were.
As technology improved, it became clear that exosomes are not just waste.
Annonse
They're part of a highly advanced communication system. Cells use these tiny bubbles to send messages to each other.
But exosomes can also provide information when something is wrong in the body. Researchers believe they can reveal both cancer and neurological diseases.
And perhaps they can even be used to treat such disorders.
Messages with an address
"Exosomes are small packages or letters that the cells send out," says Marit Inngjerdingen, professor at the University of Oslo's Institute of Clinical Medicine.
Her research focuses on these microscopic deliveries.
"They have a kind of address label on the outside that recognises the recipient cell," she explains.
Inside lies a cargo of proteins, genetic material, fats, and metabolic substances.
When an exosome finds its recipient cell, it merges with the cell membrane and unloads its cargo inside. These substances then help reprogram the cell.
This system allows cells to communicate with their neighbours, which is likely crucial for local cooperation between them.
Found in the blood
It’s also possible that the communication extends far beyond local areas. Researchers have found exosomes in blood and other body fluids.
"Maybe they have more far-reaching effects," says Inngjerdingen. "But it could also just be that excess exosomes from tissues are released into the blood."
Either way, exosomes in the blood may prove to be extremely useful.
Annonse
Indicates disease
When a cell creates exosomes, it packs them with some of the substances inside it. This becomes a kind of signature for what's happening in the cell. If disease develops, that signature can change in distinct ways.
Other research has shown that such changes in exosomes can occur in both neurological and autoimmune diseases.
This suggests exosomes may serve as biomarkers – measurable indicators of disease. Studies on conditions like arthritis, lupus, and systemic sclerosis have shown promising results.
Such measurements could one day enable much faster diagnoses.
This is especially relevant to the condition Inngjerdingen studies:
Cancer.
Weakens immune cells
Cancer cells also release exosomes.
"We know that cancer cells actively use exosomes to spread and make room in the surrounding tissue," says Inngjerdingen.
"They can also communicate directly with immune cells and influence them. Some studies show that immune cells exposed to cancer exosomes in the lab lose some of their function," she says.
They argue that more knowledge about this could give us new weapons against cancer.
Professor Marit Inngjerdingen.(Photo: Oslo University Hospital)
Biomarker for cancer
The fact that cancer cells secrete exosomes also means they can be detected in body fluids.
"Exosomes are promising as early biomarkers for cancer, but there's still a lot of uncertainty here," says Inngjerdingen.
The number of exosomes increases in line with the size of the tumour. This might mean that the tumour has to grow fairly large before the signal in the blood is strong enough to be detected.
Still, regardless of this challenge, Inngjerdingen believes exosomes could become very important in the fight against cancer.
Kills cancer cells
The body also uses the small vesicles as weapons. Our own immune cells produce exosomes that contain toxic proteins, Inngjerdingen explains.
"These exosomes can attach to cancer cells and kill them," she says.
Several research groups are now exploring how we can use this, preferably in combination with other medicines and treatments.
"We're investigating whether we can produce exosomes that kill cancer cells and use them in therapy," says Inngjerdingen.
Her research team will soon publish the results of a study where they tested this on animals with cancer.
Another possibility is to develop medicines that weaken the cancer cell's ability to release its own exosomes. This could prevent the tumour from growing and spreading.
Inflammation and intestinal disorders
Inngjerdingen explains that there is currently a lot of research on how exosomes can be used against disease.
In Austria, researchers have started testing medicines for chronic inflammation. Their approach uses exosomes from stem cells to communicate with and calm down overactive immune cells.
Other researchers are exploring how the tiny vesicles can be used to monitor activity in the gut.
"Bacteria also produce exosomes," says Inngjerdingen.
These can enter the bloodstream, potentially offering insight into imbalances in the gut flora.
Need better tools
Inngjerdingen stresses that exosome research is still in its early days.
Many challenges remain, such as creating more precise tools for detecting exosomes in tissues and body fluids. And finding effective, affordable methods to produce large quantities of the small vesicles.
"I hope stem-cell-derived exosome therapies for inflammation will be available within the next five years," says Inngjerdingen.
But when it comes to exosome-based cancer treatments, she believes it will likely take longer.
Duan et al. 'Exosomes in autoimmune diseases: a review of mechanisms and diagnostic applications', Clinical Reviews in Allergy & Immunology, 2025. DOI: 10.1007/s12016-024-09013-2 (Abstract)
