Authors: Louise White
The formation of a blood clot is a dangerous medical emergency, with the potential to trigger strokes, heart attacks and other serious health problems. Currently, identifying the exact location of a blood clot is time-consuming and can involve the use of up to three different clinical methods.
In an effort to reduce treatment times for blood clot patients, Peter Caravan’s team at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MA, USA) have developed a method, tested in rats, that may in the future allow doctors to quickly search the entire body for a clot in a single scan.
Current methods for locating a blood clot involve ultrasounds to check the carotid arteries or legs of the patient, magnetic resonance imaging to examine the heart and computed tomography to view the lungs. Caravan stated: “Patients could end up being scanned multiple times by multiple techniques in order to locate a clot. We sought a method that could detect blood clots anywhere in the body with a single whole-body scan.”
In a previous study, Caravan and his team were able to identify a peptide with specific binding affinity for fibrin, the insoluble protein fiber present in blood clots. In their current work, the researchers built on this to develop a blood clot probe by attaching a radionuclide to the peptide, enabling detection anywhere in the body by positron emission tomography.
The researchers used a range of radionuclides and peptides, as well as a variety of chemical groups for linking the radionuclide to the peptide, in order to identify which combination of these would provide the brightest positron emission tomography signal in the blood clots. They eventually constructed 15 candidate blood clot probesthat were then tested both in vitro and in vivo in order to analyze their efficacy.
“The probes all had a similar affinity to fibrin in vitro, but, in rats, their performances were quite different,” says Caravan. Some probes were metabolized rapidly in the body and could no longer bind to blood clots, however some others were resistant and remained stable.
The research team is now pushing forward with the next phase of research and is continuing to investigate the best-performing probe out of the 15, termed FBP8, which contained copper-64 as the radionuclide. The group is hoping to start testing the probe in human patients in Autumn this year, with the hope that it may be approved for routine use in a clinical setting within approximately 5 years.