Farewell, Tooth Fairy - Stem Cell Research in Dentistry

Farewell, Tooth Fairy
10/4/04
The Osgood File (CBS Radio Network)
ACFnewsource
Research is being done on stem cells from tooth pulp
In 2000, Dr. Songtao Shi and Dr. Stan Gronthos of the National Institute of Health (NIH) reported a surprising discovery: they found stem cells inside adult teeth. When his six-year-old daughter Julia lost a tooth, Dr. Shi inside and had a flash of inspirationÛmaybe baby teeth contain stem cells too? The next time his daughter lost a tooth, Shi was ready. He rushed the tooth to the lab, extracted the pulp, broke it apart into individual cells, and placed the cells in a Petri dish with culture medium. He incubated the dish in a hot, humid environment with plenty of oxygen. Amazingly, some of the tooth cells started to grow.
Tests showed that baby-tooth cells behaved like stem cells. They multiplied rapidly, they stayed alive in culture for months, and they could differentiate into nerve-like cells, dentin, bone, and fat cells. When transplanted into mice, the cells grew into tooth like structures (although they lacked the hard enamel covering of real teeth).
Stems cells are immature, non-specialized cells and they can differentiate, or become many different types of tissue, such as heart muscle, nerves, or blood components. Stem cells have two notable characteristics. They divide and multiply rapidlyÛand they can keep on dividing for a long time. (Most cells in adult tissues are permanentÛthey no longer grow and divide). They can differentiate, or become different types of tissue, such as heart muscle, nerves, or blood components.
Dr. Shi and his colleagues were quite shocked to find stem cells in baby teeth as they had initially been shocked to find them in adult teeth. No one had ever looked for stem cells in teeth before, because no one expected stem cells in teeth. That's because, unlike bone, teeth never grow bigger or repair themselves. In particular, you wouldn't expect to find stem cells in baby teeth. Kids lose their baby teeth between the ages of six and 12Ûso why would cells capable of transforming into new structures exist inside a body part that is designed to be shed?
It turned out that baby-tooth stem cells grow much faster than adult-tooth stem cells. The scientists think baby stem cells are more immature than adult cells and so may have the potential to develop into a wider variety of tissue types. They also seem to develop into nerve cells more readily than adult tooth stem cells. Shi and his team dubbed the cells SHED, or Stem cells from Human Exfoliated Deciduous teeth.
At the Royal Adelaide Hospital's Hanson Institute in Australia, a team led by Dr. Stan Gronthos (who worked with Dr. Shi at NIH on the original baby-tooth research) is running an experiment where they inject human baby tooth stem cells into rat brains. He thinks stem cells may be able to replace nerves damaged by a strokeÛor maybe stimulate other brain cells to take over for the damaged nerves. Gronthos is also working with Dr. Mark Barthold of the Adelaide University School of Dentistry on an experiment where stem cells are implanted in the mouths of sheep, to see if they can grow replacement teeth.
Dr. Christopher Nosrat of the University of the Michigan School of Dentistry has experimented with adult tooth stem cells as a treatment for ParkinsonÌs disease and related illnesses. These cells seem to release chemicals that support dying nerve cells and also seem to replace dead cells. The idea is that one day, if you were to develop Parkinson's, you could just have a wisdom tooth pulled, and doctors would extract the stem cells, grow them up, and inject them in your brain to cure the condition. Past efforts to treat Parkinson's with other kinds of stem cells have failed because the cells died after transplant. Nosrat says tooth cells seem more robust, and they also release chemicals that help the remaining nerves to survive. Nosrat has also investigated using tooth cells to treat spinal cord injuries.
Researchers say it's possible that childrenÌs baby-tooth stem cells could be "banked," then used, if needed later on, to repair or replace damaged teeth, or to grown new bone or nerves. (Many parents already bank their children's umbilical cord stem cells, even though no treatments using these cells currently exists.) An advantage of using oneÌs own stem cells is there's less risk of the transplant being rejected, because the stem cells are from the patient's own body.
Tooth stem cells could offer an advantage over embryonic stem cells in treating diseases because they are less likely to develop into teratomas (tumors) when transplanted. Another advantage of tooth cells is, instead of a different individual. Finally, you'd avoid the risk that pathogens or diseases are present in the transplanted tissue.
CONTACTS
Dr. Songtao Shi: Scientist and Principle Investigator
National Institute of Health
NIDCR (National Institute of Dental and Craniofacial Research)
Division of Intramural Research
45 Center Drive, Bldg. 30
Bethesda, MD 20892-6400
Phone: (301) 435-4584
Dr. Stan Gronthos: Mesenchymal Stem Cell Group
Hanson Institute
Frone Road
Adelaide, Australia 5000
Phone 011 61 8 8222 3455
Christopher Nosrat, DDS, Ph.D.: Assistant Professor of Biological and Materials Sciences>br> Room D3218 Dentistry
University of Michigan School of Dentistry
Dept. of Biologic & Materials Sciences
Division of Prosthodontics
1011 North University Avenue
Ann Arbor MI 48109-1078
Phone: (734) 615-4388