A bee sting that can kill tumours
Published 11/08/2009 | 02:43
Microscopic “nanobees” that literally sting tumours to death have been successfully used to fight cancer, scientists said.
Researchers in the US unleashed swarms of the tiny artificial particles on human breast and skin tumours in mice.
Each spherical “nanobee”, measuring three millionths of an inch across, was armed with a cancer-killing toxin found in bee venom.
Targeting cancer but not healthy cells, the nanobees delivered a lethal “sting”. The bee toxin, melittin, destroys cells by drilling holes through them.
After four to five injections of melittin-carrying nanobees over several days the growth of breast cancer tumours in the mice was slowed by nearly 25%.
Melanoma — or skin cancer — tumours shrank in size by 88%.
Professor Samuel Wickline from the Siteman Center of Cancer Nanotechnology Excellence at Washington University School of Medicine said: “The nanobees fly in, land on the surface of cells and deposit their cargo of melittin which rapidly merges with the target cells.
“We've shown the bee toxin gets taken into the cells where it pokes holes in their internal structures.”
The nanobees are made of perfluorocarbon, an inert material used in artificial blood.
Dr Wickline's team has been investigating their use in various medical applications including the diagnosis and treatment of narrowed arteries and cancer. The nanoparticles are large enough to carry thousands of active compounds yet small enough to pass through the bloodstream and attach to cell membranes.
Melittin injected directly into the bloodstream would cause widespread destruction of red blood cells. But attached to the nanobees, blood cells and other tissues are protected from the toxin's effects.
None of the mice suffered “collateral damage” from the treatment and had normal blood cell counts and no signs of organ damage.
Once injected the nanobees congregated in cancers because solid tumours often have leaky blood vessels and tend to retain material. The same property explains how certain drugs attack cancers much more than normal tissue.
In addition the scientists loaded the nanobees with special components designed to steer them to the right target.
One targeting agent was attracted to growing blood vessels which proliferate around tumours. When this was added to the nanobees they were guided to areas of precancerous skin damage where the blood supply was rapidly increasing. As a result the spread of precancerous skin cells was cut by 80%.
In the Journal of Clinical Investigation the scientists said nanobees had the potential not only of tackling established tumours, but halting the development of early-stage cancer.