When it comes to rabies, many people immediately recall the fear of encountering a vicious dog in an alleyway as a child, and having to rush to the hospital for a rabies vaccination if they were accidentally bitten. However, researchers have found a protein to treat mice with Parkinson's disease from this disease that has a 100% incidence mortality rate.
The rabies virus that enters the body pinpoints nerve cells, 'crawls' down nerve fibers all the way to the brain, and multiplies. It doesn't take more than a few months for a person to develop complications and eventually lose their mind and die in a frenzy, and as soon as the patient develops the disease, they are basically dead.
Properties of the rabies virus It's great for treating disease
Scientists are concerned that the rabies virus favors nerve cells in the infection process. Given that the human body is full of cells, it's not easy for the rabies virus to pinpoint nerve cells, which gives it the potential to "treat" specific diseases.
The rabies virus contains a series of recognition proteins on its surface, one of which is called rabies virus glycoprotein 29 (RVG29), which not only ensures that the rabies virus gets inside the nerve cell with precision, but also helps the rabies virus break through the blood-brain barrier to reach the brain. (The blood-brain barrier is a dense barrier between blood vessels and the brain that selectively prevents certain substances from entering the brain from the bloodstream.)
Many medications are useless precisely because they cannot be targeted, or because they are too large to cross the blood-brain barrier.
Sending drugs with the rabies virus
Recently, researchers from the Chinese Academy of Sciences (CAS) and three other institutions have invented a nanoparticle that can precisely deliver drugs to the brain, inspired by the mechanisms that cause rabies.
Their design is simply like "sending a courier." The rabies virus itself is too toxic to be used directly, so the researchers turned their attention to nanotechnology. Using a 'double emulsification' technique, they created a hollow nanoparticle with RVG29 that could encapsulate the drug.
The results confirmed that the RVG29-containing nanoparticles easily penetrated nerve cells that were isolated in the blood-brain barrier. The nanoparticles with RVG29 can increase the efficiency by about three times compared to normal nanoparticles.
Current Parkinson's treatments are imperfect
With these preliminary trials, scientists chose Parkinson's as the first disease to try to treat. Parkinson's is one of the most common neurodegenerative diseases, and the cause is due to the massive death of dopaminergic neurons in the substantia nigra of the brain.
The death of these neurons is preceded by an abnormally high concentration of iron ions, which can be prevented if the concentration of iron ions in these neurons is controlled.
Thus, one type of therapy for Parkinson's relies on lowering the concentration of iron in the patient's brain. Doctors would utilize 'desferrioxamine', which acts like a magnet to suck the iron ions out of the cells.
But this kind of therapy usually does more harm than good, because while iron ions are a scourge to neurons, they are essential to the rest of the body. If you inject desferrioxamine directly into the body, it will suck up all the iron ions in the body, and because of the blood-brain barrier, very little desferrioxamine actually gets into the brain.
Potential for a viable new medical technology in mice
The study wrapped deferoxamine in nanoparticles and tested it in mice with Parkinson's disease. The results showed that both the outward symptoms of Parkinson's and some of the in vivo physiological markers were significantly improved in the treated mice.
Of course, it may take some time before this technology is ready for clinical use in the treatment of Parkinson's or any other central nervous system disease, but in any case, it's not a bad thing to have a new and viable direction for research.