Teeth grown in lab transplanted into mice (3/1/2007)

Researchers in Japan have successfully grown mice teeth in their laboratory and transplanted them into living mice.

The process is described in a paper titled "The development of a bioengineered organ germ method" in the journal Nature Methods by Dr. Takashi Tsuji and other researchers with the Department of Biological Science and Technology at the Tokyo University of Science.

Though teeth have been grown in pigs and mice before, this is the first time someone has grown them "in vitro", or outside a living organism. This has been considered a major hurdle to growing teeth for replacements in humans, because the teeth can take several weeks to fully mature, and can't be compressed until completely grown and seated in the jaw.

The process works by taking epithelial and mesenchymal tissue from an existing tooth. Both types of tissues are then refined to become stem cells, which have the ability to become connective tissue, blood vessels, and the outer surfaces of the tooth. The refinement process takes 2 days for enough cells to be grown.

The epithelial and mesenchymal stem cells are then allowed to grow until a high cell density is achieved, which forces them to become the correct type of teeth. After two weeks, the cells have become fully grown teeth, and can be implanted into a mouse.

Transplantation is then achieved by cutting a small hole in the jaw where the tooth is to be implanted. The tooth is then implanted and the area thoroughly cleaned. Two more weeks after transplantation, the teeth are seated in the jaw, and have all the qualities of an original tooth, including: blood vessels, periodontal ligaments, alveolar bone, root, enamel and dental pulp.

This groundbreaking research takes us one step closer to testing on humans.

Other researchers involved in the study include:

• Kazuhisa Nakao
• Ritsuko Morita
• Yasumitsu Saji
• Kentaro Ishida
• Yusuke Tomita
• Miho Ogawa
• Masahiro Saitoh
• Yasuhiro Tomooka
• Takashi Tsuji

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