CHICAGO -- Researchers at the University of Illinois in Chicago claim to have discovered how to make spare body parts from a person's own stem cells.

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Dental researcher Dr. Jeremy Mao set out to make new joints for people who suffer from injury or arthritis to their joints, whether it be in the knees, fingers or even in the jaw.

"About 30 million Americans have TMJ [temporomandibular joint] problems. Some of these folks have severe arthritis of the jaw joint," Mao said.

Now, Mao and fellow researcher Adel Alhadlaq have taken liquid stem cells from bone marrow, and transformed them into the solid joint of a human jaw, complete with a top layer of cartilage. Stem cells are cells that haven't developed into a specific body type yet.

It starts with making a mold of the joint, then the stem cells are mixed with chemicals that cause them to form into bone and cartilage cells. Finally, they're poured into the mold with another chemical that solidifies the cells under ultraviolet light, according to Mao.

Stem cell molding like this has never been done before. This first experiment used animal stem cells, so the bone can't be used in people. But further studies will use a patient's own stem cells, and make spare parts that can be used.

"Hopefully, in the near future, this could be applicable in patients who have severe arthritis, fractures and so forth," Mao said.

Mao said there's just one drawback with the animal stem cells. He said the bone they make is too soft, but he's confident that that problem can be solved in future experiments.