|Photo by Simon Pearson|
As most of the stories eventually mentioned, often inappropriately low in the copy, the Chinese team did not grow teeth from stem cells found in urine. Their starting material was not stem cells, but the few live cells we all excrete when we urinate.
The team collected those cells from urine and turned them into embryonic-like stem cells called iPS cells. This is the same process scientists use to convert cells from other sources such as skin or blood into iPS cells. The resulting cells -- like all iPS cells -- have the ability to form all tissues in the body, including teeth.
But those iPS cells were not able to form teeth by themselves. They only did this when they were mixed with another type of stem cell from mice. When the two-cell type mix was transplanted into the jaws of mice it resulted in “tooth-like structures” 30 percent of the time. And these structures were only about a third as hard as human teeth.
I guess some headlines are just too hard to resist.
Even the news site that gave the most detail about the actual science EmaxHealth had a headline full of errors: “Scientists grow human teeth from stem cells in urine.”
The CBS story did a poor job with the science in the top few paragraphs, but did go on to quote a well respected expert, Chris Mason from University College London saying that the only thing the study showed was that urine would not be a viable way to regenerate teeth:
“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. You just wouldn’t do it this way.”The study was published in the journal Cell Regeneration.
Complicating this issue for people trying to understand this work is a second study published this week in the journal Stem Cells. The authors from Wake Forest University presented follow-up work to a study they published in 2006 suggesting that a few stem cells can indeed be found in urine (here's a description of that work). In their latest paper, the authors claim that those stem cells are more versatile than most adult stem cells, a claim that is sure to generate controversy and needs to be replicated.