By Emma Yasinski
With the right mixture of molecular signals, mice – which normally only grow a single set of teeth – can be coerced into growing replacements, according to a study recently published in the journal Development.
The study related to mice, but it suggests that “formation of a third set of teeth might be possible” in humans, Abigail Tucker, Ph.D., Dean for Research at King’s College in London and senior author of the paper, told Incisor. “If we could target the right cells at exactly the right time, that would be a very futuristic way to solve the problem of tooth loss.”
Some animals, such as crocodiles, are polyphyodonts, meaning they regenerate teeth throughout their lifetimes. Others, including humans, are diphyodonts, meaning they only form two sets of teeth during their lifetime. Mice are naturally monophyodont; they only form one set.
Dr. Tucker, who specializes in developmental biology, wondered how the body knows to stop producing teeth, and whether or not the signals can be controlled.
“Why can’t we have more than two sets of teeth, but snakes can? This was essentially the question that drove my research in the Tucker lab,” said Elena Popa, a graduate student in Dr. Tucker’s lab and first author in the paper, in a Q & A that accompanied the study.
First, Dr. Tucker’s team compared the dental lamina in mice to that in minipigs, which grow two sets of teeth. While minipigs maintain their dental lamina, mice lose theirs shortly after birth. The researchers analyzed the molecular signals in both animals’ lamina and found that the mice lacked the signaling activity of a molecule called Wnt.
Wnt is known for playing important roles in development, and specifically in tooth formation of some mammals. The researchers manipulated the gene so that signaling was restored in the dental lamina of the mice. Lo and behold, new teeth began to form.
“It’s a simple experiment but has a key message, which is that the reason a mouse doesn’t have a second set of teeth is that the first generation of teeth inhibits this from happening,” they explained in the Q&A. “This has important consequences, as it means that if this inhibition could be lifted, an extra set of teeth might be possible.”
To understand more about the molecular pathways involved, the King’s College team cultured cells from the dental lamina of the mice. When the cells were removed from the environment of the animal’s mouth, their ability to form new teeth returned. The researchers hypothesized that adjacent teeth may send signals that decrease Wnt activity.
Next, Dr. Tucker hopes to figure out how the permanent tooth might inhibit the creation of a replacement during normal development. She has access to a snake colony, and since snakes have constant tooth replacement, she plans to compare them to other species, such as mice, that only have one set of teeth.
Author: Contributing writer Emma Yasinski received her Master of Science (MS) in science and medical journalism from Boston University. Her articles have also appeared at TheAtlantic.com, Kaiser Health News, NPR Shots, and Genetic Engineering and Biotechnology News.
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