Monday, April 23, 2012

Nanostructures can treat all kinds of brain diseases

Diseases of the brain are often hard to treat, because the tissue is easily damaged, and it is hard for drugs to cross the barriers that prevent molecules from entering brain areas. Patients coping with well-known illnesses such as Alzheimer's, cerebral palsy, stroke, autism and multiple sclerosis all suffer from brain damage that severely impacts their life. It means finding ways to stop these diseases is very important, and a method devised by Wayne State University and the National Institute of Child Health and Human Development may be able to treat them all. Scientists made a nanostructure that decreases the inflammation commonly found in the aforementioned illnesses, and has already undergone a few successful tests.

Brain inflammation. Credit.
There are many ways by which brain tissue can get damaged, as is illustrated by the vast amount of different diseases there are. When neurons, the cells of the brain, get damaged it is frequently accompanied by inflammation. Cells send out distress calls which attract immune cells, tasked with clearing the debris and removing any cells that died from whatever it is that damaged the brain. However necessary, the immune system can overreact and thereby further increase damage, which is why clinicians often have to treat with anti-inflammatory drugs. The nano device developed by Wayne State University and the National Institute of Child Health and Human Development does something similar.

Blood Brain Barrier
One of the problems of getting drugs into the brain is the Blood Brain Barrier (BBB). It is very selective in allowing molecules to pass into the brain, and that means scientists need to adapt their treatment strategy. The nanostructure is able to pass the BBB, and, in addition, is also capable of specifically targeting the culprits of brain inflammation. After passing the BBB, the nano device is taken up by overactive immune cells in the brain resulting in their death, ameliorating inflammation.

Getting into the brain and killing the overachieving immune cells requires a carefully constructed nano device. The researchers achieved this by building a tree-like structure called a dendrimer. Such molecules are excellent for delivering drugs, as the widely branched structure allows for coupling of vast amounts of medically active molecules. In this case, the scientists added a cell-killing compound to the dendrimer. Fluorescent molecules were also attached, to be able to follow the structures after being injected in patients.
The general idea of a dendrimer.
Experiments and results
To assess whether the structures show any efficacy in live animals, the scientists set out to test their nano drug in newborn rabbits. They did not provide a clear explanation for using such young rabbits as model for so-called neuroinflammation, but the results showed that a single injection significantly improved their condition. Muscle control and a decrease in stiffness were noted, which are hallmark symptoms for cerebral palsy. It should also give similar improvements in other brain diseases accompanied with inflamed neurons. That is, if the scientists can show it is equally effective in human patients, something that will be assessed in future studies in coming years.

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