Teeth Regrown in Mice

Wednesday, 20 February 2008 13:41

After recreating new teeth from milk teeth and wisdom teeth, researchers come now with another novelty in this field.

Japanese researchers have succeeded to regrow teeth directly into the mouths of adult mice starting with single cells in lab dishes, the first steps towards a new promising technique to be applied in the case of missing teeth in humans.

The team led by Takashi Tsuji at the Tokyo University of Science, Japan, took single-tooth mesenchymal and epithelial cells (the two embryonic cell types that develop into a tooth) from mouse embryos.

They first grew each cell type separately and stimulated these cells to multiply in larger numbers before injecting them into a drop of collagen (a sticky protein) gel. In a few days, the cells developed into tooth buds, the first stage of normal tooth formation.

The researchers inserted the bioengineered tooth buds into cavities left after they had extracted healthy incisor teeth from eight-week-old adult mice. The implanted buds developed in the cavities tiny teeth about 1.3mm long after two weeks. The new teeth had a perfectly normal structure and composition, with a healthy blood supply, bone and nerve connections, being made up by root, enamel, dental pulp.

Previous researches to regenerating teeth were realized in 14 days by growing teeth buds in the kidneys (in a sub-renal capsule) of mice before transplanting them into the mouths of other mice.

The teeth buds were grown in a lab dish starting with marrow stem cells and embryonic epithelial cells, but the "kidney" teeth buds were not proven to develop into normal teeth that could be inserted in a mouse's jaw.

This research "provides the first evidence of successful reconstitution of an entire organ via the transplantion of bioengineered material," wrote the authors. "This study represents an important contribution to the field of tooth regeneration because it demonstrates how teeth can be grown directly in the mouth," says Jeremy Mao, at the Columbia University College of Dental Medicine in New York, US. "Earlier studies have shown alternative methods of regenerating teeth directly in animals’ mouths. Tsuji’s approach is different from earlier methods because it involves culturing the cells in a collagen gel. But the advantage of using such a gel mixture remains unclear." noted Paul Sharpe at Kings College London, UK.

As the mesenchymal and epithelial cells possess the potential to grow into other organs and hair follicles, this method could have more applications. "We hope to collaborate with dentists and clinicians in various fields to develop artificial organs for people," said Tsuji.