Radioactive Heart Scan

Radioactive nanobodies identify fat and debris despoits in artery walls

(RxWiki News) Scientists have found a method for injecting a radioactive antibody fragment capable of showing deposits of fat and debris in artery walls most likely to rupture and cause heart attacks.

The antibody has shown success in animal trials, and is expected to be tested in humans in clinical trials following toxicology testing to assure it is safe.

"Familiarize yourself with symptoms of a heart attack."

Alexis Broisat, the study’s lead author and a post-doctoral fellow at the University of Grenoble in France, said the ability to detect vulnerable coronary plaques is a major clinical challenge. Most cardiovascular-related deaths occur as a result of ruptured plaque.

She noted there still is no early, reliable and non-invasive tool that can be used in clinical practice to detect such potentially dangerous plaques.

Investigators created radioactive antibody fragments called nanobodies that attached to particles in artery plaques called vascular cell adhesion molecule-1 (VCAM1). In laboratory tests, scientists found that the radioactive nanobodies were attracted to VCAM-1, which plays a major role in the inflammation process. Ongoing inflammation in a plaque deposit is a critical warning that it could rupture.

During the study researchers injected a solution containing radioactive fragments into the bloodstream of mice with artery plaques. SPECT and CT imaging scans were used to detect the radioactive particles.

After radiolabeling, they found that some nanobodies remained in laboratory and mice blood for six hours, allowing imaging of the mice up to three hours after injection. The imaging scans revealed plaque in the aortic arches of the mice.

If clinical tests confirm success in people, the tests could be a major step toward preventing cardiovascular deaths associated with plaque ruptures.

“The early detection of trouble looming ahead could trigger steps for intervention, possibly involving the aggressive modulation of risk factors,” Drs. Matthias Nahrendorf, and Peter Libby, and Jason R. McCarthy, of Harvard Medical School wrote in an accompanying editorial.

Clinical trials are anticipated to determine whether the radioactive nanobodies are safe, beneficial and cost effective. Researchers also hope to assess whether the fragments could cause adverse immune reactions in humans.

The study was published today in Circulation: Research, an American Heart Association journal.

Review Date: 
March 29, 2012