In a latest discovery scientists from Massachusetts Institute of Technology have managed to implement a radiation-free approach to monitor brain activity, enabling to image brain molecules without using any chemicals or radioactive materials.
Alan Jasanoff, the study’s lead author, has stated that the current technique invfolves monitoring brain molecules using radioactive probes. This involves using a fragment of DNA or RNA that can be radioactively labelled. However, these probes provide low resolution images and do not offer the ability to monitor real-time molecular and chemical changes taking place in the brain. This study was published today in the December 2 issue of Nature Communications.
The scientists invented new brain sensors by modifying a naturally occurring peptide called calcitonin gene-related peptide (CGRP), which is activated during periods of inflammation or migraines.
These sensors will enable scientists to detect particular areas of the brain, as the blood vessels surrounding the target zone will become dilated. This change can be identified using imaging techniques such as magnetic resonance imaging (MRI).
Jasanoff added that this technology came at the right time and will shape the way brain diseases are modified. He said, “This is an idea that enables us to detect molecules that are in the brain at biologically low levels, and to do that with these imaging agents or contrast agents that can ultimately be used in humans. We can also turn them on and off, and that’s really key to trying to detect dynamic processes in the brain.”
The team of scientists used the CGRP probes to identify protease enzyme that aids in the chemical breakdown of proteins into amino acids. They monitored protease molecules as they are an indicator of diseases such as Alzheimer’s and cancer. They used these models to ensure that they were on the right path and that their research was valid.
The researchers bioengineered the peptide molecules in such a way that they remained bounded within a vicinity so that they did not engage with the surrounding blood vessels. However, when the molecules detected protease nearby, they were free to roam around and caused the nearby blood vessels to dilate. Using this dilation to their benefit, the scientists could use MRI scans to locate protease molecules.
Regarding the properties of these molecules, Jasanoff remarked that they do not directly identify protease molecules but the regions surrounding the molecules which can be monitored using MRI. The team further added that using this technology they aim to identify neurotransmitters which are present in abundance in the brain and relay information to muscles spread over the body.
By coming up with a way to mark neurotransmitters such as dopamine and serotonin, the researchers will be able to identify biochemical changes that take place in the brain in mental diseases such as depression and anxiety, and will be able to justify mood swings and cognitive functionality.
In order to tag neurotransmitters, the scientists will have to bioengineer the peptide molecules in such a way that they are able to escape their vicinity in the presence of a particular neurotransmitter.
Jasanoff said that they aim to detect neurotransmitters that are 100-fold lower than currently detected. The only hindrance that Jasanoff team faces is that they want to minimize the use of imaging agents in organisms, so they can effectively use them in humans.
Another way Jasanoff and his team will be able to utilize this technology is by manipulating the molecules in such a way that they exhibit a turn-on function when a gene of interest expresses itself. In this way the scientists could track changes in blood flow caused by CGRP molecules to identify cells that are causing genes to express themselves in a certain way.
This could in turn help scientists to assess the special relation between specific cells and genes, and utilize this information to calculate when and where certain genes express themselves in certain parts of the brain.
Jasanoff mentioned that there are several genes that have the ability to express themselves under certain conditions, and there are many conditions that can invoke a unique response from genes. Therefore, it is vital to harness this information.
Jasanoff’s team is also working on unique ways to deliver the peptide molecules without having to inject them, which would mean the scientists have to figure out a better way to enable the molecule to pass through the blood-brain barrier, and keeps large molecules at bay by preventing them to penetrate the brain structure.
What Is MRI? How Does It Function?
Magnetic Resonance Imaging (MRI) is a noninvasive diagnostic test that takes detailed images of the soft tissues in the body. Unlike a CT scan, which uses X-rays to capture images, MRI captures images using magnetic field, radio waves and a computer. MRI selects images slice by slice, meaning that it can take images of different layers of tissue thus helping diagnose strokes, tumors and bone fractures.
When we are placed inside an MRI machine, the millions of hydrogen atoms present in our body align with the magnetic field whilst the radio waves push the atoms away and change their polarity. The MR sensor detects the time it takes for the hydrogen atoms to return to their normal state of alignment. MRI measures the water content of tissues in the body. The computer processes the different characteristics of the tissues and presents them in a black and white image, showing detailed characteristics of the tissue and can detect even the smallest of abnormalities.
The images can be rotated and viewed from any angle, giving physicians a more accurate representation of the anomaly. Finally, a dye is injected into the bloodstream, to highlight hard to detect tissue regions in the body. MRI can also be used to view arteries and other blood vessels. MRI cannot detect fluid that is in motion; therefore, a contrast dye containing gadolinium, a chemical element with metallic properties, is injected that highlights the blood vessels making them visible in MRI images. The dye could prove to be toxic in certain patients, especially those suffering from a kidney disease, as their body cannot properly excrete it.
According to OECD Health Statistics 2015, the US population performed 107 MRI scans per 1,000 population, approximately 10%. As MRIs are used to detect a variety of mental diseases such as anxiety, depression, autism etc, it is vital to enable safe and reliable operation, as it is easy to misdiagnose them.
Side Effects Of Radiation
Radiation imaging techniques such as X-rays can cause cells to mutate leading to cancer. The amount of radiation a person is exposed to depends on the region being imaged, but due to the risks associated, one should consider safer alternatives.