When joint cartilage wears away due to injury or disease, bone rubs on bone, which can cause severe pain and joint instability.
It's then that people turn to artificial joint replacement surgery, which uses plastic and smooth metal surfaces that might only last 10 to 15 years.
For several years, Duke University professor of orthopedic surgery Farshid Guilak and his team have used adult stem cells to grow real cartilage, but with limited success.
"What we're hoping to do is develop a therapy that can put off that joint replacement," Guilak said.
Now, a new technique developed by Nobel Prize for Medicine winner Shinya Yamanaka, of Japan, is the breakthrough Guilak needed.
"These cells actually come from skin cells and they are converted into an embryonic-like state through the use of four genes that we insert into them," Guilak said.
The cells are called pluripotent, because they can become any type of cell, including cartilage.
"We put a reporter in there so that when the cells became cartilage cells they would actually grow green," said Brian Diekman, a post-doctoral associate in orthopedic surgery.
Once identified, the cartilage cells can be sorted out to build cartilage tissue – formed to the shape of the joint on a scaffold of special-woven fibers.
Another benefit of the technology is collecting tiny samples of cartilage for testing arthritis drugs.
"It allows us to look at all different types of therapeutic drugs and screen out the ones that would work best," Guilak said.
Because the pluripotent cells can be developed from skin cells, Guilak said he could also produce an unlimited supply – both for testing and for biological joint replacement.
Duke researchers say testing the cartilage in human patients with cartilage injury and osteoarthritis is still probably three to five years away.
The Duke study is published in the Oct. 29 edition of the journal, "Proceedings of the National Academy of Sciences."