The entire tooth units were inserted into the lower jaws of mice and attached successfully to jaw bones, and the rats were able to chew normally, the researchers wrote in their paper, published online in the open access journal 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.
What this means for humans
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."
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 mould, 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 fibres 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.
(Reuters Health, July 2011)