The latest treatment for crippling jaw disease

He has spent nearly two decades researching the condition and potential cures. About 25% of adults worldwide – 90% of them premenopausal women – have difficulty eating and talking, chronic mouth pain, arthritis and other issues due to degeneration in the cartilage disc that hinges together two key jawbones.

Now, using animal models, scientists at UCI, UC Davis and The University of Texas School of Dentistry at Houston have successfully removed a tiny bit of existing rib tissue, isolated its cartilage cells and utilised them to tissue-engineer jaw disc cartilage via a “self-assembling” process the experts created.

They then surgically inserted the new cartilage into the faulty hinge point of the jaw joint. The approach was allogeneic, meaning that the rib cells were taken from one individual and the new cartilage was implanted into another. Two months later, the defects were completely gone.

“This is a terrible condition. I have friends and colleagues who have suffered from it, so it’s extremely satisfying to think we could provide relief,” said co-author Jerry Hu, UCI principal design engineer, who developed a critical stage of the work: transforming the sometimes “poorly behaved” rib cells into smoothly functioning jaw disc cartilage.

Researchers and physicians have long struggled to effectively treat TMJ afflictions. One infamous technique involved putting Teflon into the jaw area; the substance disintegrated, with bits ending up in the brain and elsewhere.

“It was a disaster,” Athanasiou said. After hearing about that and the subsequent dearth of research, he plunged in, first at UT, then at Rice University and UC Davis, and – since July 2017 – at UCI. 

The next steps will be to ensure long-term effectiveness and safety of the implant in the animals, followed by clinical trials.

“We hope this will lead to new treatments for humans,” said Natalia Vapniarsky, a veterinary pathologist at UC Davis’ School of Veterinary Medicine, where the surgery was done. “Most medical management approaches for TMJ disc issues currently aren’t curative but palliative."

"Patients come back needing further help, but by that time, the disc and joint are destroyed beyond repair, so all that can be offered is a prosthetic. We wanted to explore an earlier, regenerative solution.”

Orange County, a biomedical hub where UCI is located, is the perfect place for translating the breakthrough work into a usable product, Athanasiou said.

He and Hu noted that while it might be possible to take someone’s own rib tissue and grow it, the process would require a lengthy delay compared to using readily available implants. Unlike other tissues and organs, cartilage from one body is not rejected when implanted in another body.

Athanasiou said the results might also apply to the treatment of hip, knee and other joint problems. The animals that did not receive the cartilage implants saw a 300% increase in osteoarthritis, which many TMJ patients eventually develop, while the treated ones did not.

“This is the first time that cogent healing has been shown in the TMJ area and, I dare say, the first time anyone has shown successful biomechanical healing in any joint. It’s key that we can achieve regeneration of an ailing tissue with our engineered implant, one that’s mechanically suited to withstand stresses,” Athanasiou said. “So we believe this represents an important first in all joint healing studies.”

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Image credit: University of California, Irvine.