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The work, led by Batrakova and her colleagues at the UNC Eshelman School of Pharmacy's Center for Nanotechnology in Drug Delivery, is based on exosomes, which are tiny spheres harvested from the white blood cells that protect the body against infection. The exosomes are made of the same material as cell membranes, and the patient's body doesn't recognize them as foreign, which has been one of the toughest issues to overcome in the past decade with using plastics-based nanoparticles as drug-delivery systems.
"Exosomes are engineered by nature to be the perfect delivery vehicles," said Batrakova, who has also used this technique as a potential therapy for Parkinson's disease. "By using exosomes from white blood cells, we wrap the medicine in an invisibility cloak that hides it from the immune system. We don't know exactly how they do it, but the exosomes swarm the cancer cells, completely bypassing any drug resistance they may have and delivering their payload."
To test the system out, the researchers took a chemotherapy drug called paclitaxel, which is already used effectively to treat breast, lung, and pancreatic cancers, but with severe side effects, such as hair loss, muscle cramping, and diarrhoea.
Watch: Introduction to Cancer Biology
The researchers loaded this drug inside exosomes taken from mice, and then set them loose on a petri dish containing multiple-drug-resistant cancer cells. They called their treatment exoPXT, and they found that they needed 50 times less of it to kill the cancer cells than they did when they used commercially available versions of paclitaxel.
In mouse models of drug-resistant lung cancer, exosomes were loaded with a dye in order to track their progress through the lung, and it was found that the exosomes were thorough in seeking out and marking cancer cells.
The results have been published in Nanomedicine: Nanotechnology, Biology and Medicine.