Drawing inspiration from an unlikely source — the deadly rabies virus — scientists have developed an effective way to obliterate brain tumor cells in animals.
The unique disease pathway of the rabies virus is complex and often fatal because the virus can latch onto nerve cells that cross the blood-brain barrier, thereby infecting brain cells.
In the new study, researchers from Sungkyunkwan University in South Korea have modeled a brain-cancer therapy on a similar pathway — but instead of injecting a virus into test subjects, they used nanoparticles modeled in the same size and shape as rabies to reach the brain’s nerve cells.
“Rabies virus-inspired silica-coated gold nanorods are fabricated by mimicking size, shape, surface glycoprotein property and in vivo behavior of the rabies virus,” write the authors in the journal Advanced Materials.
The tiny nanoparticles are made of gold rods, which is vital to the treatment’s efficacy. When the researchers blast the golden nanoparticles with a laser light, the gold rods heat up to more than 120 degrees Fahrenheit and can kill surrounding tumor cells.
“These nanorods not only resemble the appearance of the actual rabies virus but also travel into the brain through the neuronal pathway, bypassing the blood–brain barrier,” report the authors.
So far the researchers have tested their model in mouse studies and have found success with the approach. However, human trials likely remain years away, and the researchers would have to clear several safety hurdles, including the health impact of the accumulated nanoparticles, before gaining clearance.
How to Mimic the Rabies Virus
Previous studies have explored the efficacy of imitating the rabies disease pathway, but the new study appears to be the first to rely on the laser-heating technique.
To assess their treatment method, the Sungkyunkwan University researchers led by Yu Seok Youn, injected the rod-like nanoparticles into the tails of four mice with brain tumors. From there, the nanorods moved to the brain, passing the blood-brain barrier, and gathered near the tumor cells.
The researchers then directed a laser at the gold nanorods until they reached 50 degrees Celsius, or about 122 degrees Fahrenheit. The heating technique acted as the researchers hoped — the nanorods quickly heated up and destroyed adjacent cancer cells.
Ultimately, the technique significantly reduced the size of the brain tumors in the mice, reports the team in Advanced Materials.
However, the researchers remain unsure of the exact pathway that the gold nanorods traveled to reach the brain. Youn believes that they traveled via the same route as the rabies virus, as the lead researcher reported to Science.
Other scientists who reviewed the study surmise that the nanoparticles traveled a different route — and that might lead to rods reaching cells other than the brain tumor cells, which could harm healthy tissue.
But Youn and his colleagues remain committed to fine-tuning their results and believe in the disease-fighting ability of nanoparticles.
Brain tumors affect tens of thousands of people every year, and many of those tumors are malignant, according to the American Brain Tumor Association. Some types of brain cancer have very low survival rates. For example, glioblastoma has a five-year survival rate of just 4%, according to the American Cancer Society.