Dr. Guilak notes, "There are so many people in their 50s and 60s who have severe osteoarthritis, and no options other than joint replacement. But you don't want joint replacement when you're 55 because revisions can be a problem. So the goal is to use technology to put off joint replacement – not just by patching defects but by resurfacing the whole joint.

Whether human hips and knees can be grown in the laboratory remains to be seen. It's also unclear how long such tissue might last. "It could be a few years or 10 or 15 years," Dr. Guilak says. "There is such a mechanical demand on joints, we won't know until it's actually being done."

Drug Screening
In addition to therapeutic applications, Dr. Guilak says iPSC technology can provide patient-specific tissue models to screen for potential arthritis medications.

"There are no drugs that moderate disease severity [in OA]," he points out. "To under better understand how different drugs might work, you need a large source of cartilage from a controlled genetic background. With iPSCs, you can make genetically specific cartilage for different patients. So if you know one person is susceptible to arthritis and another isn't, you can grow cartilage with those genetic backgrounds from just a few skin cells."

Other Ideas
Eben Alsberg, PhD, associate professor of biomedical engineering and orthopaedic surgery at Case Western Reserve University in Cleveland, says Duke scientists have successfully tackled one of the most vexing problems in cartilage tissue engineering: identifying the best cell source for research.

"Dr. Guilak's group has presented a very elegant approach to identify and purify a more uniform population of iPSC-derived cells with improved cartilage-forming potential, which is tremendously exciting for regenerative medicine applications and for creating models to study cartilage growth, repair and disease," explains Dr. Alsberg, who is also working on laboratory-grown cartilage. Eventually, he hopes to use a patient's own cells to produce cartilage for joint repair.

Warren Grayson, PhD, assistant professor of biomedical engineering at John Hopkins University in Baltimore, Md., is also enthusiastic about the Duke research.

"It's really fascinating," he says, "because it speaks to the idea of getting specific patient's cells to treat osteoarthritis, and I think that has been one of the major challenges – how do you get enough stem cells for any particular application? What they have shown is you can use a few skin cells to create iPSCs abundantly and without any morbidity and transform them in such a way that they can be used for specific therapies. That's a really huge advantage."

Dr. Grayson's lab is using stem cells to develop patient-specific, anatomically correct bone grafts for use in reconstructions of congenital defects and traumatic injuries.