Mice Teeth

It is generally conceded that members of the genus Mus have been accorded little respect in our society. They are the Rodney Dangerfields of their species. A research team of scientists sits around in a laboratory, sipping Yoo Hoo and hitting the onion dip while musing over what to try next before their grant expires.

"I know," one of the White Coats says, "let's get a mouse and inject it with something."

"Capital!" the rest agree, and first thing you know some mouse-intensive research is under way from which few rodents will escape without serious emotional trauma. The animal-rights people have been strangely mute on this subject, even though mice are routinely sliced, diced and marinated with every bacterial and surgical insult you can think of in the name of science. Unfortunately, mice have been notoriously lax in practicing any sort of birth control. With a little forbearance, they could have achieved the enviable status of the endangered gnatcatcher, and nobody would dare mess with them.

Only Mickey, Jerry and Mighty have emerged unscathed from this rodent ethnic cleansing, a lesson the balance of the non-union mouse population without agents seems not to have learned. A pity, because the April 1999 issue of the Journal of the American Dental Association records the newest depredation on mousedom being performed at Guy's Hospital in London. We assume the personnel at Gal's Hospital want nothing to do with this outrage, especially if it involves interaction with actual mice.

I quote JADA: "They recently discovered Barx-1, a gene that controls what type of tooth is grown. By blocking a Barx-1 inhibitor called BMP4 (the first three BMPs were already spoken for) -- which causes incisors to grow -- they modified cells in mice that normally create incisors and caused the cells to produce molars." Stay with me here, because this gets a little weird. When the genetically modified cell samples were two or three days old, and without so much as a by-your-leave from the mouse, researchers implanted them just outside an adult mouse's kidney. This mouse had left the room briefly for a little run on the wheel, and in its absence, its buddies "volunteered" it for the kidney/tooth experiment. You can imagine how surprised and honored it felt when it returned to find itself on the OR schedule. "Why me?" were its exact words.

"The kidney is one of the optimum sites for growing teeth," says Paul Sharpe, PhD, a professor of craniofacial development at Guy's Hospital and a member of the research team. I bet you didn't know that -- and you call yourself a dentist! I bet you would have implanted the cells in the mouse's jaw someplace, and that's why Paul is on the team and you're not.

Anyway, two or three weeks later, a tooth developed just outside the mouse's kidney, resulting in the mouse having to get up several times during the night, turning on lights and bonking into things to the point where the compassionate researchers removed it and examined it.

"Yessir, that's a tooth all right," they all agreed, placing it carefully under the patient's pillow and referring the confused mouse to its urologist for some post-op treatment.

Now the researchers, flushed with success, say they "want to learn more about which genetic markers and commands are given to cause teeth to form in a certain formation and position." Dr. Sharpe says, "Regrowing teeth would be an obvious aim."

Before you get all flushed yourself with the portents of this amazing discovery, the guys back at the hospital say they hope that in 10 to 20 years their work will lead to teeth being grown on demand. They want to develop a gel containing the genetic material that would form a new tooth wherever it was placed. "Within two or three weeks, a new tooth would grow and work exactly as the lost tooth," Dr. Sharpe exults. The "lost tooth?" Yes! Here is the best part -- the researchers say, ideally, the gel "would be placed in a cavity in the patient's mouth."

These scientists are playing pretty loose with the term "cavity." We know what a cavity is, and you don't stuff genetic material in it. Amalgam maybe, or composite resin, so apparently we've got 10 to 20 years to get this straightened out. The point is, their intention is good news for those of us who have enough trouble with our kidneys as it is. But who is going to explain this to the mouse?