Experts grow whole tooth units using mouse stem cells

HONG KONG (Reuters) - Scientists in Japan said on Wednesday they have created teeth -- complete with connective fibers and bones -- by using mouse stem cells and successfully transplanted them into mice, a step they hope will lead to progress in stem cell research.

The entire tooth units, which were inserted into lower jaws of mice, attached successfully with jaw bones and the rats were able to chew normally, the researchers wrote in a paper in PLoS One (Public Library of Science).

"The bioengineered teeth were fully functional ... there was no trouble (with) biting and eating food after transplantation," wrote Masamitsu Oshima, assistant professor at the Research Institute for Science and Technology, Tokyo University of Science.

The researchers hope this is a step to help the development of new human organs grown from a patient's own cells.

"At present, researchers worldwide do not have the method to culture three-dimensional organs in vitro (outside the body)," Professor Takashi Tsuji, who led the research, wrote in his reply to questions from Reuters.

"It is important to develop technologies for the culture of the bioengineered organ ... for the realization of future organ replacement regenerative therapy."

Stem cells are the body's master cells and source of all cells and tissues. They are undifferentiated and experts believe they can generate all the cell types of the organ from which they originate.

Because of their ability to generate different types of cells and multiply and self-renew, scientists hope to harness stem cells to treat a variety of diseases and disorders, including cancer, diabetes and injuries.

FROM STEM CELLS TO WHOLE TOOTH UNITS

Tsuji's team removed two types of stem cells from the molar teeth of mice and grew them in the laboratory. To control the length and shape of the teeth, the cells were placed in a mold, where they grew into entire tooth units.

The entire tooth units were then transplanted into the lower jaws of one-month-old mice. They fused with the tissues and jaw bones around them after about 40 days, Tsuji said. Nerve fibers too could be detected in the new teeth.

Tsuji stressed the importance of finding the right "seed cells" for reparative therapy. In this case, entire tooth units could be grown because the stem cells were taken from molar teeth of mice -- where they later grew into enamel, dental bones and other parts that comprised a regular tooth unit.

In 2010, U.S. researchers created an artificial lung that rats used to breathe for several hours.

(Editing by Yoko Nishikawa)