Trojan Horses: Nanoparticles sneak drugs into brain to battle cancer
I just read an interesting article in the Berkeley Science Review about using nanoparticles to make chemotherapy more effective against a type of brain cancer called glioblastoma. I was then surprised and proud when I realized one my former science-writing students, Dharsi Devendran, wrote it.
Although rare, glioblastoma is an invasive and deadly brain cancer with octopus-like tentacles that are difficult to completely remove with surgery. Even the standard combined treatment of surgery, radiation and chemotherapy isn’t very effective — people typically die within months of diagnosis. So researchers are actively searching for better treatments.
Although it is difficult to fight, glioblastoma also has a weakness. In its rush to feed itself, it accelerates the blood vessel formation process and creates hole-riddled blood vessels around the tumor. Because cancer drugs are small enough to slip through these holes, they can exploit this defect—but they also need a strategy to cross the blood-brain barrier in order to reach the tumor.
Acting like a security system for the brain, the blood-brain barrier is a network of blood vessels that allow essential nutrients to enter while blocking harmful molecules. Unfortunately, it also blocks life-saving chemotherapy drugs, unless researchers can find clever ways to sneak them through the barrier.
Ting Xu, PhD, professor of materials science at UC Berkeley, and her collaborators are developing tiny nanocarriers that can envelop and protect chemotherapy drugs as they move through the blood, across the blood-brain barrier, and into the brain to the glioblastoma tumor tissue.
The researchers designed a new nanocarrier, called a 3-helix micelle (3HM), out of proteins with molecules on the surface that fit into specific proteins found only on the surface of the tumor cells — like fitting a key into a lock. Once the 3HM nanocarriers access the tumor cells, they release their chemotherapy drugs to help destroy the glioblastoma.
Xu’s team has shown that their 3HM nanocarrier is twice as effective at reaching glioblastoma cells as liposomes, a nanocarrier made of fatty acids that is a standard in nanotechnology drug delivery. This is in part because the 3HM is five times smaller than liposomes.
“We still don’t understand the mechanism completely,” said JooChuan Ang, a graduate student in Xu’s group, in the article. “Size is definitely a factor, but there could be other factors that contribute…”
This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.