July 30, 2013
Potty Mouth: Chinese Researchers Make Teeth From Urine
Michael Harper for redOrbit.com - Your Universe Online
A team of researchers from China's Guangzhou Institutes of Biomedicine and Health have demonstrated human teeth can be generated by stem cells from a very interesting source: Urine. The Chinese team says they can also generate other solid organs and tissues from human waste.
It's been observed before that stem cells are found in urine. Furthermore, when these stem cells are collected, scientists can coerce them to become induced pluripotent stem cells (iPSCs) which are capable of generating other types of cells. These cells can then be genetically molded and coaxed into other organs and tissues, including heart muscle cells and neurons.
Duanqing Pei and the rest of the team from Guangzhou Institutes of Biomedicine and Health now say they've developed a way to coerce these iPSCs into teeth-like structures. Though these collections have the essential components of human teeth, the final product isn't quite as hard as the teeth humans are naturally born with. Their study is published this week in the open-access journal Cell Regeneration.
Just as it's been observed in normal tooth development, the new system created by the Chinese team makes use of the interaction between the epithelial cells and mesenchymal cells. The former cells are responsible for producing the enamel which coats the teeth while the latter builds out the internal components inside the tooth. These include the cementum, dentin and pulp.
Pei and crew first gathered the stem cells from urine and mixed them with chemicals to encourage the epithelial cells to lay flat from the iPSCs. They then took these flat cells and mixed them with embryonic mesenchymal cells from mice. The final product was then transplanted into the mice.
Though the stem cells from urine were mixed with embryonic mouse cells and implanted into the rodents, structures began to grow which, according to the team, closely resembled human teeth. They claim they have a very similar makeup, but have only one-third the hardness of a typical human tooth.
Their method is also a bit inconsistent at the moment and is capable of reproducing human teeth only 30 percent of the time. The new method is still a breakthrough say the researchers, and they're already working on ways to improve their system.
For instance, they claim they might better grow human teeth if they use human mesenchymal stem cells as opposed to mouse cells. The controversial nature of stem cell research, however, could make it difficult for the team to move forward in this regard. Additionally, Pei and team say they could continue modifying the tissue culture to grow a stronger tooth. In this instance, the bud of a tooth could be grown in the lab before being transplanted into a human jaw to finish its development.
Though this new system is a breakthrough in the field of regenerative cell growth, some say there are better places to be looking for the crucial iPSCs than urine.
"It is probably one of the worst sources, there are very few cells in the first place and the efficiency of turning them into stem cells is very low," explains professor Chris Mason, a stem cell scientist with the University College London in an interview with BBC News.
"The big challenge here is the teeth have got a pulp with nerve and blood vessels which have to make sure they integrate to get permanent teeth."