A Safer Way to Image Molecules in the Brain
Scientists from MIT have devised a new probe that enables them to image molecules in the brain without using any chemical or radioactive agents. The new probe consists of proteins and once it hits a particular target, the probe induces blood flow changes that can be seen by MRI or other imaging techniques. Their work is reported in the journal Nature Communications.
The current approach to imaging molecules in the brain is to tag them with radioactive probes. However, these probes deliver low resolution and they can't easily be used to watch dynamic events, explains Alan Jasanoff, an MIT professor of biological engineering.
To make their probes, Jasanoff and colleagues modified a naturally occurring peptide called calcitonin gene-related peptide (CGRP), which is active primarily during migraines or inflammation. They engineered the peptides so that they are trapped within a protein cage that keeps them from interacting with blood vessels.
In the study, the probes were used to detect enzymes called proteases, but the ultimate goal is to use them to monitor the activity of neurotransmitters, which act as chemical messengers between brain cells. When the peptides encountered proteases in the brain, the proteases cut the cages open and the CGRP caused nearby blood vessels to dilate. Imaging this dilation with MRI allowed the researchers to determine where the proteases were detected.
"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," says Jasanoff. "We can also turn them on and off, and that's really key to trying to detect dynamic processes in the brain."
Proteases can be used as biomarkers to diagnose diseases such as cancer and Alzheimer's disease. However, Jasanoff's lab used them in this study primarily to demonstrate the validity of their approach. Now, the MIT team is working on adapting these imaging agents to monitor neurotransmitters, such as dopamine and serotonin, that are critical to cognition and processing emotions. To do that, the team plans to modify the cages surrounding the CGRP so that they can be removed by interaction with a particular neurotransmitter.
The researchers hope to detect levels of neurotransmitter that are 100-fold lower than what have been detected so far. "We also want to be able to use far less of these molecular imaging agents in organisms. That's one of the key hurdles to trying to bring this approach into people," Jasanoff points out.
His lab is working on ways to deliver the peptides without injecting them, which would require finding a way to get them to pass through the blood-brain barrier. This barrier separates the brain from circulating blood and prevents large molecules from entering the brain.
Source: Massachusetts Institute of Technology
Image credit: The Researchers
Published on : Mon, 5 Dec 2016
The SonoSite EDGE II is a high-resolution, all-digital, 9.0-pound (4.1 kg) ultrasound system with a 12.1in. LED full-bleed glass display. The Edge II boosts improvements in cardiac and abdominal image quality through DirectClear Technology and a new...
Remarkable image quality, right at the point of care. The Trident system revolutionizes breast tissue imaging by incorporating a micro-focused tube, unique specimen image processing algorithms and amorphous selenium direct digital detector. The...
About the Affirm® breast biopsy guidance system Our passion to offer innovative interventional tools that advance breast health fueled the development of the Affirm breast biopsy guidance system. This simple add-on to any Hologic 3D Mammography™-capable...
If you’re striving for a faster, more accurate diagnosis at an affordable cost… Our Surpia CT scanner will help you achieve it. Supria is ideal for broad range of CT examinations. It delivers excellent image quality. It’s easy to use. It’s designed...
We recognize that the best chance any patient has at getting better is a clinician at their bedside with all the right answers and the confidence to act. SonoSite education and training is the industry standard – no other point-of-care ultrasound manufacturer...