Biomedical Engineering

Athanasiou Lab Postdocs Regrow Jawbone in Dog with Cancer

When Whiskey, a 10-year old Münsterländer dog, stopped chewing on his favorite treat of beef tendons, owner Tom Swierk took him to the vet to check for a bad tooth. His problem turned out to be a whole lot worse. Whiskey had squamous cell carcinoma, a very common type of oral cancer in dogs and humans, that had grown into a 6 cm tumor– about the size of a thumb. In order to prevent the cancer from spreading to Whiskey’s lymph nodes, the cancerous bone had to be amputated.

Mr. Swierk’s vet researched the best options for Whiskey, and referred him to the Dentistry and Oral Surgery Service at the UC Davis School of Veterinary Medicine, where he fell under the care of Dr. Frank Verstraete and Dr. Boaz Arzi. Although the amputation would save Whiskey’s life, it would cost him the normal functioning of his mouth.

With such a large gap in his lower jaw, Whiskey would not be able to chew normally and could not play ball or tug of war. The teeth and bones would also gradually fall out of alignment. If the surgeons used only a titanium plate to span the gap where the bone was removed, the loading pressures on the plate would have eventually caused bone around it to resorb and over time, the jaw would be worse.

Fortunately for Whiskey, Dr. Arzi is also a postdoctoral researcher in Prof. Kyriacos Athanasiou’s cartilage tissue engineering laboratory. He had discussed jaw defects like Whiskey’s with another Athanasiou Lab postdoc, Dr. Dan Huey, and the two had devised a new technique to regrow the jawbone. They had tried it successfully on five dogs before, but Whiskey’s defect was the largest yet encountered.

First, the surgeons screwed on a titanium plate and molded it to the bone’s original shape. Then they removed the plate and cut out about 6 cm of cancerous bone. They screwed the plate back in and inserted a cartilage and ceramic foam scaffold that Dr. Huey had saturated with exactly the right amount of human bone morphogenetic protein (BMP) into the gap, up against the titanium plate, and finished the surgery. The BMP attracted stem cells that were already present in the dog’s tissues into the scaffold, and stimulated them to become bone cells. Within 2 weeks they could already feel hard tissue, and by 3 months, CT scans showed that the new bone looked almost indistinguishable from Whiskey’s own bone.

“The devil is in the little details,” says Dr. Arzi. “You have to use the exact right amount of the bone morphogenetic protein and handle it just right or else you can get swelling or bone growing in the wrong places. We have had good results because of the collaboration with tissue engineers in the Biomedical Engineering Department.”

Whiskey had no complications after the surgery, and, like all the other dogs operated on by the team, healed perfectly in a very short time. Mr. Swierk said that there wasn’t even swelling. There are no scars, aside from a nearly invisible little divot in part of the lower lip. It was the biomedical engineering expertise in determining and applying the correct dosage and devising the protocol for handling the bone morphogenetic protein that made Whiskey’s surgery so successful.

Today, Whiskey enjoys chewing on his treats, playing with his toys, and living a happy life with his family. The missing teeth do not affect the way he eats or plays. By now the team has used this regenerative medicine technique on 8 dogs, and all have had the same spectacular results. Their long-term prospects are good.

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