A new study has discovered a network of genes that enable sharks to develop and regenerate their teeth throughout their lifetime. These genes allow sharks to replace whole rows of their teeth in a conveyor belt type fashion. Although scientists have known for a while that certain fish such as sharks can develop rows of teeth with the capacity of lifelong regeneration for a while now, the genetic mechanisms that enable these processes were very poorly understood.
A research team led by Dr. Gareth Fraser from the University of Sheffields Department of Animal and Plant Sciences has identified that a special set of epithelial cells form (Very densely packed cells that line the epidermis). These epithelial cells are called the dental lamina, and they are the ones responsible for the shark’s lifelong continuation of tooth development and regeneration. These cells are not only found in sharks, humans also possess this set of cells, which facilitate the production of replacement teeth, but only twice- once for baby teeth, and another for adult teeth. Once the adult teeth have grown, this specialized set of cells is lost. Dr. Fraser and his team found that these tooth-making genes found in sharks have been conserved through more that 450 million years of evolution, and are the source of the first vertebrae teeth. Therefore, these tooth genes are responsible for making all vertebrae teeth from sharks to humans.
However, in many mammals including humans, this tooth regeneration ability, that utilizes these genes and cells, has been greatly reduced over time due to the many mammals not needing this attribute for survival. Sharks on the other hand, constantly are in need for new sets of teeth. One of the main reasons they are so successful at hunting prey is because of their rows of razor sharp teeth that regenerate before they get dull or decay. This is why sharks are one of the only species today that have retained this ability from the original vertebrae species’. One of the main conclusions that Fraser made through this research was the possibility of harvesting and using these epithelial cells in humans to allow for humans to grow teeth after the adult teeth have already grown. This is a very possible possibility because as stated earlier, humans possess these cells in adolescence when they are needed for the growth of baby teeth, and then again for adult teeth. But, at some point during adolescence, we lose these cells, and they break down due to them being not necessary for future survival. But according to Fraser: “There is a possibility we can re-invigorate them with future dental therapies. The ‘Jaws’ films taught us that its not always safe to go into water, but this study shows that perhaps we need to in order to develop therapies that might help humans with tooth loss”. These scientists noted that this research will take many years, and that this discovery of these cells and genes is just the stepping stone into this, but they are confident that “Regenerating teeth will happen.”