Gold in nanoparticle form is perhaps more precious than the macroscale variety when it comes to treating diseases. While the usual application areas for nanotechnology, such as electronics, are finding uses for gold nanoparticles, it is perhaps in the area of drug delivery and the detection and treatments of diseases such as cancer where they are destined to have their biggest impact.
Along these lines, researchers at Northwestern University have used gold nanoparticles to treat a common form of cancer, known as B-cell lymphoma—the most common type of non-Hodgkin lymphoma.
In research to be published in the journal Proceedings of the National Academy of Sciences, C. Shad Thaxton, M.D., and Leo I. Gordon, M.D. showed that they could trick B-cell lymphoma, which prefers to eat HDL (high-density lipoprotein) cholesterol—otherwise known as the “good cholesterol”—into eating gold nanoparticles instead of the HDL. Once the B-cell lymphoma cells start eating the gold nanoparticles (or artificial HDL particles), they get plugged up and can no longer feed on any more cholesterol. Deprived of their favorite food, the lymphoma cells essentially starve to death.
With this treatment, Thaxton and Gordon demonstrated that it could inhibit human B-cell lymphoma tumor growth in mice.
"This has the potential to eventually become a nontoxic treatment for B-cell lymphoma which does not involve chemotherapy," said Gordon in a press release. "It's an exciting preliminary finding."
Since the nanoparticles have nearly the same size, shape and surface chemistry as natural HDL cholesterol, Thaxton believed when he first developed it that it might have some use in treating heart disease. "At first I was heavily focused on developing nanoparticles that could remove cholesterol from cells, especially those involved in heart disease," Thaxton said in the press release.
When Thaxton gave a presentation on the nanoparticle back in 2010, Gordon was in the audience and it occurred to him that it might have some use in treating lymphoma.
Gordon had noticed that lymphoma patients had dramatic decreases in HDL cholesterol, so he thought this nanoparticle might have some use in drug delivery in cancer patients.
When the researchers started to collaborate, they made a surprising discovery. The nanoparticle by itself was just as effective at reducing the lymphoma as the nanoparticle in combination with the drug was.
It was at this point that they began to examine the mechanisms by which the artificial HDL nanoparticles interacted with the lymphoma. They discovered that the spongy surface of the gold nanoparticle draws out the cholesterol from the lymphoma cell and the gold core blocks the cell from absorbing any more cholesterol.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.