In a world first, Japanese researchers reported Sunday they had successfully replaced natural teeth in mice with teeth that were created in a lab dish from single cells.
Writing in the journal Nature Methods, a team led by Takashi Tsuji of the Tokyo University of Science describe how they took two kinds of cell -- mesenchymal and epithelial cells -- that develop into a tooth.
They first grew each cell type separately to make larger numbers of them and then injected them into a sticky protein called collagen.
The tooth germ grew into a tiny tooth about 1.3mm long. The researchers then extracted the incisor from an eight-week-old adult mouse and inserted the bioengineered tooth.
After two weeks, the transplant was found to be growing perfectly, with root, enamel, dental pulp, bone, blood vessel -- the same composition and structure as a normal tooth.
The study "provides the first evidence of successful reconstitution of an entire organ via the transplantion of bioengineered material," the authors say.
The tooth could be grown in 14 days either in organ culture or in a so-called sub-renal capsule, which means it was attached to the kidney of another mouse in order to grow.
Previous work in this field has yielded teeth buds that were grown in a lab dish using marrow stem cells and embryonic epithelial cells and then nurtured in sub-renal capsules. But so far, there has not been a demonstration that the buds could develop into normal teeth if inserted in a mouse's jaw.