Doctors looks to biologics to repair joints

March 6, 2008

By Debra Sherman

SAN FRANCISCO (Reuters) - The orthopedics industry is using more biology and less metal to repair injured and diseased joints.

Researchers attending the annual meeting of the American Academy of Orthopaedic Surgeons in San Francisco this week said they are slowly unlocking the doors to regenerative medicine using stem cells, gene therapy and tissue engineering.

"It's the future of our specialty," said Dr. Thomas Einhorn, chairman of the Department of Orthopedic Surgery and professor of orthopedic surgery, biochemistry and biomedical engineering at Boston University.

Historically, the orthopedist's arsenal looked much like a carpenter's. It was dominated by heavy metal -- cages, screws, saws, drills and metal implants for joints such as hips and knees.

Stem cell therapy could eventually eliminate the need for joint replacement, said Einhorn, who last year performed his first hip replacement surgery using the patient's own stem cells.

The undifferentiated, unspecialized stem cells can morph into specialized cells with specific functions in the body. Adult stem cells are available from a number of sources, including bone marrow and fat.

Stem cells from a patient's own body are being used to repair bones, ligaments, cartilage, muscle, spinal cord and nerves.

In the hip replacement surgery, Einhorn extracted bone marrow from a middle-aged male patient, sent it to a lab that removed everything but the stem cells, then put the cells in a spray gun and coated the hip implant to induce rapid bone growth over the implant.

"I don't know if I'll see it in my career, but we're certainly moving that way. It might take 20 years before we can totally regenerate a joint that way," Einhorn said.

Dr. Scott Rodeo, co-chief of Sports Medicine and Shoulder Service at the Hospital for Special Surgery in New York and an associate team physician for the Super Bowl champion New York Giants, said animal studies suggest that stem cells and bone morphogenic proteins (BMPs) can be used to repair rotator cuff tears in the shoulder, a common sports injury that often requires surgery.

BMPs are a group of growth factors and cytokines known for their ability to induce the formation of bone and cartilage. They are sold by Medtronic Inc and Stryker Corp.

Stem cell therapy may also have applications in spine fusion, said Dr. Scott Boden of Emory Spine Center.

"We have a tougher time in the spine," he said, adding that it may just require more cells to form bone there.

Implanting BMPs may "attract other stem cells to the site and tell them to become bone cells," he said.

(Editing by John Wallace)

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