NEW IMAGING TO HELP CATCH AND TREAT ARTHRITIS EARLY

TORONTO, Can. (BIO2002)--Early detection of arthritis may soon be possible in doctor's offices with new compounds that "light up" joint cartilage in magnetic resonance imaging, according to Gerald Rosen, research professor at the University of Maryland Biotechnology Institute.

Rosen of UMBI's Medical Biotechnology Center in Baltimore, Md. and C.S. Winalski of Brigham and Women's Hospital, Harvard Medical School have developed safe compounds that bind to joint cartilage in tests on leg joints of rabbits.

"As arthritis progresses, the cartilage becomes thinner," explains Rosen. "In MRI images, healthy cartilage 'light up' as where our compounds bind and diffuse the cartilage. A physician would then determine the progression of the disease by simply following decrease in the intensity of the contrast media in the MR image," adds Rosen.

Currently, radiology is not very good at evaluating cartilage. The researchers hope to develop a clinical test for arthritis, using it to detect arthritis at an early stage where therapy could be effective, similar to routine clinical tests, such as mammography and prostate specific antigen (PSA).

The new contrast compounds with MRI will significantly improve early detection of arthritis and allow many more people to avoid long-term debilitating effects. Eighty percent of people over the age of 65 suffer from arthritis, but most don't consult with a physician until the disease has progressed to discomfort, extensive pain, or possibly expensive, time-consuming joint replacement.

Recent advances in arthritic medication can arrest the disease if the drugs are started at the onset of the disease. But early detection would allow many more people to avoid getting to the point of heavy medication.

Currently, there is no universally accepted best technique for accurate imaging of articular cartilage-a critical component of efficient, painless joint function. Injections of gadolinium, known as a contrasting agent that shows up cartilage, has been promising, say the researchers. Gadolinium is the only compound approved by the U.S. Food and Drug Administration for such use. However, such images require extensive post processing.

The new compounds, positively-charged dendrimer-linked niroxides, bind tightly to the surfaces of negatively charged proteoglycans in cartilage tissues at the same concentrations used for gadolinium.

The new compounds for cartilage imaging have a higher degree of positive charges to bind to the surface of cartilage and more potency to be seen by MRI than gadolinium.

"We are developing an arthritic model and evaluating it when compared to standard pathological evaluations. And, I have to say that at this point, it looks pretty good," concludes Rosen, who is also the Isacc E. Emerson Professor at the University of Maryland School of Pharmacy.

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The University of Maryland Biotechnology Institute was mandated by the state of Maryland legislature in 1985 as "a new paradigm of state economic development in biotech-related sciences." With five major research and education centers across Maryland, UMBI is dedicated to advancing the frontiers of biotechnology. The centers are the Center for Advanced Research in Biotechnology in Rockville; Center for Agricultural Biotechnology in College Park; and Center of Marine Biotechnology, Medical Biotechnology Center, and the Institute of Human Virology, all in Baltimore.