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Featured abstract preview: Sheep model can improve understanding of GAE 

23 days ago

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Melanie Padgett Powers, SIR TODAY 2022 | Tuesday, June 14

Abstract 348: Assessing Effects of Geniculate Artery Embolization in a Non-Surgical Animal Model of Osteoarthritis

Presentation: Wednesday, June 15 at 4:03 p.m., Boston Convention and Exhibition Center, room 251

Researchers successfully created a sheep model that mimics knee osteoarthritis in humans, which will allow IRs to better understand geniculate artery embolization (GAE).

The findings of abstract No. 348, “Assessing Effects of Geniculate Artery Embolization in a Non-Surgical Animal Model of Osteoarthritis,” will be presented Wednesday at 3 p.m. as part of Scientific Session 35, Embolization 2.

GAE blocks blood flow in the synovium, or the lining around the knee, to reduce inflammation and thus pain. Prior research by Yuji Okuno, MD, PhD, in Japan has also shown success using embolization to treat shoulder pain and plantar fasciitis in the foot, said presenter Andre Uflacker, MD, of Medical University of South Carolina.

“This has sparked a rush of scientific interest in this kind of research, and this is why we thought an animal model like this one would be useful to answer questions that will ultimately arise,” Dr. Uflacker said.

GAE uses superselective angiography and particle embolization of the involved area of the knee lining. Patients with inflamed synovium consistently have increased vascularity—more and larger blood vessels—and possibly arterial venous shunting, or abnormal connections between arteries and veins, Dr. Uflacker said. They also have “tumor blushing,” which is an increase in blood flow similar to what is seen in some tumors.

The sheep model created by Dr. Uflacker’s team does not require surgery, which would allow IRs to study the therapeutic mechanism of GAE and disease progression without needing a veterinarian or orthopedic surgeon.

Dr. Uflacker’s team injected 700mg of sodium monoiodoacetate under fluoroscopy guidance into the left stifle of six castrated rams. MRI and invasive angiography were used to identify the regions with greatest disease severity for super-selective embolization. Twenty-four weeks later, study and scoring of the synovium post-mortem showed the successful creation of a sheep model of osteoarthritis in which angiographic, histopathological, MRI and kinematic data can be obtained to study GAE effects.

This ovine model can help fill several gaps in GAE knowledge, Dr. Uflacker said.

“Is there a correlation between high blood flow to the synovium and things like disease progression and symptom improvement if we shut down that increased blood flow? We also don’t fully understand the histopathological changes and how those correlate with symptoms. Do we see decreased presence of pain fibers, or nociceptive innervation, in the synovium when we decrease hypervascularization of the synovium?

“And how do all those things fit together for symptom improvement and actual disease progression?” he continued. “We know that osteoarthritis gets worse as time goes on, and it’s entirely possible that GAE could be disrupting the cycle of inflammation.”

The use of GAE could also decrease the use of opioids for knee pain, Dr. Uflacker said.

“There are millions of people all around the world with early knee osteoarthritis that have not progressed yet to end-stage joints that require surgery,” he explained. “Most of those people have limited choice of therapies that improve their pain. One road we don’t want people going down is the road of oral narcotic pain medication to treat their knee osteoarthritis. This research is extremely relevant in reducing the overall amount of opioids that are consumed in the United States and around the world.”


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