Stem cells generated from human urine have been used by Chinese scientists to grow structures in mice resembling human teeth.
The ability to "regenerate teeth with patients' own cells" is an
"ideal solution" to the loss of teeth through accidents or disease, the
researchers say in a paper describing their results in the
peer-reviewed, open access journal Cell Regeneration this week.
While most cells in our tissues, such as muscle cells and red blood
cells, are highly specialized, stem cells have the potential to grow
into many different types of cells. Because of that, many researchers
have been trying to use them to regenerate entire new organs.
The
Chinese researchers, led by Duanqing Pei and Jinglei Cai at the Chinese
Academy of Sciences Key Laboratory of Regenerative Biology and
Guangdong Provincial Key Laboratory of Stem Cell Biology and
Regenerative Medicine, generated stem cells from kidney lining cells in
human urine and grew them under special conditions into sheets of
epithelial tissue — a type that includes skin and teeth.
They implanted the human tissue with tissue from the jaw of a mouse
embryo – to encourage it to grow into a tooth – in the kidney of a
mouse. Three weeks later, they collected tooth-like structures with the
hardness "found in the regular human tooth." Closer examination showed
that the human tissue had turned into cells called ameloblasts that
secrete enamel, the hard, bone-like substance on the outside of the
tooth.
Pei and his team first reported their technique to generate stem cells from urine in 2011.
That has advantages over traditional techniques such as removing a
chunk of a person's skin, acknowledged William Stanford, a University of
Ottawa researcher who holds a Canada Research Chair in integrative stem
cell biology.
"Who really wants a centimetre squared taken out of them?" he mused.
Growing various kinds of human tissues inside a mouse kidney is a common technique used by stem cell biologists, Stanford said.
"It's a developmental biology trick," he told CBC News in a phone interview.
In the course of doing so, researchers will occasionally grow what looks like teeth by accident.
The Chinese researchers have modified the technique to grow teeth
intentionally, Stanford said. However, he questioned whether teeth were
the most useful thing to try to grow, since there are already implants
and other artificial replacements for teeth that work quite well.
James Ellis, a developmental and stem cell biologist at Sick Kids
Hospital in Toronto, said in an email that scientists would have to be
able to regenerate human teeth without the use of mice and their tissues
in order for it to be actually practical for use in dentistry.
"This will be very challenging," he added.
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