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Friday, August 27, 2004 - Page updated at 01:15 P.M.
Mesh cage in shoulder blade used to grow new jaw bone
By Emma Ross
According to this week's issue of The Lancet medical journal, the German doctors used a mesh cage, a growth chemical and the patient's bone marrow, containing stem cells, to create a new jaw bone that fit exactly into the gap left by the cancer surgery.
Tests have not been done to verify whether the bone was created by the blank-slate stem cells, and it is too early to determine whether the jaw will function normally in the long term. But the operation is the first published report of a whole bone being engineered and incubated inside a patient's body and transplanted.
Stem cells are the master cells of the body that go on to become every tissue in the body. They are a hot area of research with scientists trying to find ways to prompt them to make desired tissues, and perhaps organs.
The operation was done by Dr. Patrick Warnke, a reconstructive facial surgeon at the University of Kiel in Germany. The patient, a 56-year-old man, had his lower jaw and half his tongue cut out almost a decade ago after developing mouth cancer. He since had been able only to slurp soft food or soup from a spoon.
This patient could not have that procedure because he was taking a potent blood thinner for another condition and doctors considered it too dangerous to harvest bone from elsewhere in his body since extraction leaves a hole where the bone is taken, creating an extra risk of bleeding.
Artificial jaws made from plastic or other materials are not used because they pose too much of a risk of infection.
"He demanded reconstruction," Warnke said. "This patient was really sick of living."
Warnke and his group began by creating a virtual jaw on a computer, after making a three-dimensional scan of the patient's mouth.
The information was used to create a thin titanium micro-mesh cage. Several cow-derived pure bone mineral blocks the size of sugar lumps then were put inside the structure, along with a human-growth factor that builds bone and a large squirt of blood extracted from the man's bone marrow, which contains stem cells.
The surgeons then implanted the mesh cage and its contents into the muscle below the patient's right shoulder blade. He was given no drugs, other than routine antibiotics.
The implant was left in for seven weeks, when scans showed new bone formation. Scans showed new bone continued to form after the transplant.
Four weeks after the operation, the man ate a German sausage sandwich, his first real meal in nine years. He eats steak now, although he complains that, because he has no teeth, he has to cut the meat into such small pieces that it's cold by the time he finishes it.
He has reported no pain or any other difficulties, Warnke said, adding that he hopes to be able to implant teeth in the new jaw about a year from now.
Paul Brown, head of the Center for Tissue Regeneration Science at University College in London, said tests may not be able to show whether the new bone came from stem cells, rather than from the growth factor alone.
Biopsies of the jaw bone later could provide answers on the quality of the bone, experts said.
"Just making the gross tissue shape right isn't really the problem," Brown said. "It's what the shape of the tissue is at the microscopic and ultramicroscopic level. That's the architecture which is so tricky and which is what gives function."
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