Sharks can replace lost teeth. Wouldn’t it be nice if humans could, too?
Building on two decades of research, scientists from Kyoto University are now developing a drug that could regrow teeth.
Their work began in 2006, when a team led by molecular biologist Katsu Takahashi was investigating kidney disease in mice missing the USAG-1 protein, which inhibits bone and cartilage development. The modified mice ended up healthy (and resistant to kidney injury), but they had a few too many teeth. Upon further investigation, the researchers discovered that USAG-1 regulates tooth growth in mice, and removing it allowed additional teeth to form.
By 2020, they had created an antibody that neutralizes USAG-1 locally. The antibody not only “rescued” tooth development in mice with congenital tooth deficiency but also stimulated new tooth growth in genetically normal mice, as well as in ferrets and dogs.
Takahashi has now founded a startup, Toregem Biopharma, which plans to develop this antibody into a drug for humans. The first human trial, set to begin in September, will test the antibody on middle-aged men missing a molar. If the drug is safe for humans, it will be tested for efficacy on children with congenital tooth deficiency.
According to the Japanese newspaper The Mainichi, the company hopes to bring the drug to market as soon as 2030.
If humans were sharks, they wouldn’t need this drug. As Britain’s Natural History Museum noted in 2016,
Sharks have a ‘conveyor belt’ of teeth within their jaws, so when a tooth is lost it can be replaced – sometimes within an hour. They develop multiple sets of these teeth over their lifetimes. Humans also possess these genes, but our ability to grow new teeth stops after we have developed our adult teeth. A special set of cells called the dental lamina are responsible for the lifelong continuation of tooth development and regeneration in sharks…..
Humans also have cells that allow us to develop new teeth, but we only form baby teeth and one set of adult teeth before these cells are lost.
Researchers believe the same genes are used to grow all vertebrate teeth, from sharks to mammals. But the ability to regenerate teeth has reduced over time in mammals.
Scientists hope it might one day be possible to use the newly discovered information about how sharks grow teeth to develop therapies for humans. It is possible doctors may be able to ‘switch on’ the same genes in humans, and allow us to replace teeth we lose as adults.
