When an old joint injury flares up, it might be post-traumatic osteoarthritis (PTOA). That’s because a joint injury can set in motion a complex physiological process that leads to slow-burn degradation of the hard, slippery tissues essential to healthy joint function. PTOA typically isn’t apparent until long after recovery from the original joint injury. Most of the people affected won’t be diagnosed until the disease reaches a stage at which there are few therapeutic options. A team of scientists at the Center for Advanced Imaging Innovation and Research is looking for MRI biomarkers of PTOA that may provide early clues about this condition, the origins and mechanisms of which still elude firm medical understanding.
“There’s nothing really specific to study this disease,” said Amparo Ruiz, PhD, assistant professor of radiology at NYU Langone Health and scientist at the Center for Advanced Imaging Innovation and Research and the Tech4Health Institute. Dr. Ruiz researches noninvasive markers of PTOA and has led recent research on a promising candidate: a peptide called P15-1. P15-1 has been shown to have certain protective effects on cartilage, and scientists suspect that these effects may stem from similarities between P15-1 and another substance called hyaluronan, which is essential to cartilage health but when fragmented tends to promote inflammation.
“Cartilage is one of the first things to get degraded” in PTOA, said Dr. Ruiz. “That’s why we decided, let’s try this peptide and see what happens.” Together with colleagues, Dr. Ruiz developed P15-1 contrast agents that allowed the team to conduct studies on cell cultures, animal models, and histological samples. In the process the researchers used seven types of imaging to visualize physiological phenomena in individual cells, isolated tissues, and live joints.
In a study published in the journal Osteoarthritis and Cartilage in 2022, the researchers report “the first in vivo evidence that hyaluronan-related inflammatory response in cartilage after injury is a common finding” and demonstrate that molecular imaging can be used to effectively investigate the origins of PTOA and potential therapies.
Although the P15-1 imaging technique developed by the researchers is just a piece of a bigger PTOA puzzle, it is also a new tool the team can use to further its investigations. “That’s basically where our approach of molecular imaging came up,” said Dr. Ruiz. “To try to find something that is specific and that you can use to visualize, study disease progression and monitor treatment.”
But the reserach also provides a vivid example of how disparate biomedical imaging methods can complement each other and serve to corroborate a scientific hypothesis that itself advances what can be seen through sophisticated extensions of human sight.
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