In a new research, a bunch of scientists at the University of Massachusetts Medical School have designed the first-ever human protein-based tumour-targeting MRI contrast agent.
The biohybrid composite, which can also be easily cleared by the body, could be used to detect tumours in their early stages, thanks to its enhanced MRI contrast and shorter proton relaxation time.
The discovery holds promise for clinical application, including early stage tumour detection because of the enhanced MRI contrast, according to Dr. Han, associate professor of biochemistry & molecular pharmacology at University of Massachusetts Medical School, and lead scientist of the study.
MRI is the most widely used, noninvasive and versatile tool for observing anatomical structures in soft biological tissue without the need for ionizing radiation or dangerous radionuclides.
The images, in this technique are obtained by exciting the protons found in water and fat inside the body with a magnetic field and then measuring the rate that these protons relax back to their original state. These proton relaxation times which are different for different tissues, result in the MR contrast in the final image.
The most frequently employed contrast agents in the clinic today are gadolinium-based chelates because they shorten the relaxation
time of protons. While these chelates do not provoke an immune response, which is a plus point, they do, however last or accumulate in vital organs.In the search for alternative chelates, researchers have in recent times turned naturally occurring nanomaterials.
In case of this team, they have designed a Gd-based transferrin (Tf) protein prepared by mimicking the natural biomineralization process. The Gd@TfNPs, as they are called, are better than conventionally employed Gd chelates because they amplify the MR signal more strongly, have a higher relaxivity, and are very stable.
Furthermore, these agents are also biocompatible, and are effectively cleared by the body through the hepatobiliary system.
“The Gd@TfNPs preserve the functions of Tf very well, possess superior chemical and physical properties, and are brighter compared to the Gd-based agents currently in use,” Han said.
“Such probes can immediately leave the tumor sites after delivery and we could track the overall process by MRI. Such a technique might be useful not only for visualizing tumor therapies, but for optimizing drug dose and evaluating clinical results,” said Yang Zhao, MD, PhD, of the Second Hospital of Tianjin Medical University and the paper’s first author.
