Scientists use stem cells to grow fully functioning teeth in mice

Team at Tokyo University of Science hope breakthrough could lead to technology to replace damaged or lost organs in humans

guardian.co.uk, Monday 3 August 2009 22.00 BST

Fully functioning teeth have been grown from stem cells planted in the mouths of mice, scientists said today.

The researchers in Japan hope the breakthrough could prove not only to be an important step towards being able to replace teeth in humans but eventually replacing organs, lost or damaged as a result of disease, injury or ageing.

The technology has already been used to develop limited tissues that could be transplanted into animals. But the new experiment was the first time a fresh three dimensional organ had been grown in a living animal from just a few cells.

"Tooth germs" – the tiny buds that appear before a tooth grows – were developed by the Japan-based team, according to a paper published in the journal Proceedings of the National Academy of Sciences.

Dr Takashi Tsuji, from the Tokyo University of Science, and his colleagues first removed the upper first molars from five-week-old mice. Then three weeks later, after confirming that no remaining components of the tooth root were present, they transplanted the germs into the jawbones of the mice. The seed-like tissues contained all the cells and instructions necessary to grow a tooth.

A green fluorescent protein was used to track the genes in the buds, which eventually grew into fully formed teeth with all the usual structures including enamel and blood vessels.

Tests confirmed that the bioengineered teeth were "fully functioning". The study said their hardness was comparable to normal teeth, enabling proper chewing. Nerve fibres could grow throughout and responded to pain stimulation, an important protection mechanism for the teeth.

The study said the technique could provide a prelude to "the ability to grow new, fully functional bioengineered organs inside the body from stem cells or other germ cells.

"Current approaches to the development of regenerative therapies have been influenced by our understanding of embryonic development, stem cell biology, and tissue engineering technology.

"The ultimate goal of regenerative therapy is to develop fully functioning bioengineered organs which work in cooperation with surrounding tissues to replace organs that were lost or damaged as a result of disease, injury, or ageing.

"We propose this technology as a model for future organ replacement therapies. This study represents a substantial advance and emphasises the potential for bioengineered organ replacement in future regenerative therapies."