THERE'S a dentist in London who has a picture of Mickey Mouse on the ceiling above where his patients recline.

Long before the drilling started, this was supposed to make children more at ease.

All it did for me was to instil a profound fear of cartoon rodents. And I was in my forties.

Why, I wondered — as Mickey leered down and a grinding vibration reverberated from jaw to spine — can't we simply regrow teeth? After all, we do it in childhood, when the tooth fairy swaps our baby teeth for small coins and adult choppers.

Good news: we very nearly can. Last week, in the Journal of Biological Chemistry, a team from Tokyo, including Professor Satoshi Fukumoto, said they had created cells that could make enamel, the hard outer coating of teeth.

This follows the development of a technique by Dr Jeremy Mao at Columbia University in New York City for encouraging stem cells to move to a scaffolding where they will grow to replace a missing tooth.

"In the future," says Dr Paul Sharpe of King's College London, who has also grown teeth from tooth buds, "we envision a patient who loses a tooth and wants a replacement will be able to choose between current methods and a biological-based implant — a new natural tooth."

All these attempts involve stem cells, first discovered by Canadians James Till and Ernest McCulloch in 1963.

The body's cells all have the same DNA, but depending on the tissue that they belong to — blood, skin or kidney etc — they will have different sets of genes turned on or off. And they pass those characteristics on to their descendants. When a muscle cell divides, its two daughter cells are both muscle.

Stem cells, however, have not decided which tissue they will be. When they divide, their daughters can be either stem cells or any kind of tissue cell.

In the past decade, stem cells have sparked a revolution in biosciences, creating a whole new field called regenerative medicine as scientists learn how to grow spare human parts. While teeth may well be the first, they won't be the last.

Regenerative medicine will address two huge problems faced by transplants. The first is that potential recipients far outnumber donors. Some authorities have tried to solve this by requiring that people actively opt out of organ transplant schemes. If you're in a coma and not expected to wake up, doctors presume they can "harvest" your organs unless you've left clear instructions otherwise.

The second problem is rejection. A transplanted organ has DNA that is different from the recipient's, which can cause the immune system to treat it as an invader. So transplants usually come with drugs that suppress the immune system, leaving the patient vulnerable to other infections. If we were able to grow new organs to order, from cells with the patient's own DNA, it would solve both these problems.

But stem cells have political problems, particularly in the US, where president George W Bush severely limited research funding because the main source for stem cells were embryos, usually those left over after in-vitro fertilisation but potentially from abortions. Those restrictions have been gradually eased, but more than a dozen states also have strict rules in place.

The stem cells used by the Japanese team, however, have a different source. Called "induced pluripotent stem" cells, they are made from tissue cells that have been treated to return them to a state similar to that of stem cells. No embryo, no political problem.

But real stem cells would be better. And one of the best places to find them in adults, it turns out, is in teeth. Some companies are even harvesting people's dental pulp stem cells and storing them in case they're needed in future. Soon it may be possible not only to regrow teeth, but to regrow other organs from teeth.

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  0 comments

  7 comments

  7 comments

  0 comments

  7 comments

  0 comments

  5 comments

  0 comments

  2 comments