One tiny tooth boosts the dreams of mice and men

A bioengineered mouse tooth, bottom jaw right.

JAPANESE scientists have grown teeth out of stem cells and transplanted them into mice in a world-first experiment that has boosted hopes of growing other complex organs.
The researchers took adult stem cells from foetal mice, put them in collagen, and placed them in a mouse's kidney to grow. Over two months, the cells turned into a perfectly formed tooth with bone and ligaments, which allowed it to be removed and transplanted into a mouse's mouth. Six weeks later the tooth had engaged with the animal's blood and nerve supply, causing it to behave like a naturally grown tooth.
The scientists from Tokyo University of Science yesterday reported the achievement in the journal PLoS One , saying it was a ''substantial advance'' in the quest to grow organs for people who need them.

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Associate Professor David Leavesley from the Institute of Health and Biomedical Innovation at Queensland University of Technology said it was the first time he had seen scientists grow and successfully transplant a complex organ that requires a blood, nerve and waste supply system.
''This shows that you can actually create a mature organ replacement in an artificial situation and then transplant it to become a functional tissue integrated with the recipient. That's never been done before as far as I'm aware,'' he said.
He said the project opened up the possibility of teeth being grown for people who had lost them after suffering severe gum disease, but said it was not practical to grow teeth inside people's bodies because it would require multiple surgical procedures.
''Sure, we could probably grow them in patients … but it's invasive, so there's the risk of infection,'' he said.
''If you could take it off the shelf out of an incubator and put it into a patient, that would be ideal, but they haven't done that.''
Associate Professor Leavesley said it also suggested scientists would be able to use adult stem cells to create other complex organs such as a liver, pancreas or eyes.
Scientists in several countries have already transplanted skin and bladder tissue into people, created from human adult stem cells, but they have not been able to grow and transplant complex organs.
In the 1990s, Australian scientists attempted to use human adult stem cells to grow organs inside pigs, but could not proceed because of ethical concerns.
In Melbourne, scientists at the O'Brien Institute of Microsurgery are using stem cells to help women regrow breast tissue after cancer surgery.
They have not yet reported results from their first trial.


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