Stem Cells to Be Used in Knee Therapy

12/13/05
Keck School researchers hope their efforts will help repair damaged tissue of a cartilage pad that serves as a shock absorber for the knee. Surgeons will recruit more than 50 patients for the trial.
By Alicia Di Rado
Adult mesenchymal stem cells are harvested from the bone marrow of healthy adult volunteers, then isolated and prepared for insertion into the knee.

USC orthopedic surgeons are beginning the first human clinical trial using stem cells to treat injured knee tissue.

Researchers hope the therapy, called Chondrogen, will help the body repair damaged tissue of the meniscus, a cartilage pad that sits between the main bones of the knee and acts as a shock absorber.

Chondrogen contains what are called adult mesenchymal stem cells, or MSCs, which are harvested from the bone marrow of healthy adult volunteers, then isolated and prepared for insertion into the knee. These MSCs are universally compatible similar to the “O” blood type.

In animal tests, the mesenchymal stem cells successfully helped regenerate surgically removed meniscal tissue.

The trial will evaluate the safety and effectiveness of the therapy to enhance recovery and protect joint surfaces from further damage after meniscal tissue is removed. The United States Food and Drug Administration granted clearance for the trial in April.

Regenerating meniscal tissue is a key issue in the treatment of painful knee-joint damage. Because most of the meniscus lacks a blood supply, it heals poorly. That affects countless adults: In the U.S. alone, about 800,000 people each year have surgery to remove part of a damaged meniscus.

Meniscus tears may occur in people of any age. Among the young, they often accompany sports injuries. As people age, though, the meniscus may weaken, and tears can happen in older adults through simple accidents or even seemingly innocuous movements of everyday life.

USC surgeons will recruit more than 50 patients ages 18 to 60 to enroll in the trial. Patients must be suffering from a meniscus tear or degeneration and require surgical removal of at least 50 percent of the width of the medial meniscus to treat the damage. USC is the sole site for the study.

C. Thomas Vangsness Jr., professor of orthopaedic surgery in the Keck School of Medicine of USC and chief of sports medicine, is principal investigator in the trial.

“Patients who require removal of their damaged meniscus are at a much higher risk of developing arthritis,” Vangsness explained. “To provide my patients with the opportunity to regrow their own, naturally functioning meniscus would be revolutionary for the treatment of knee injuries and for the practice of sports medicine.”

Surgeons give a single injection of the investigational treatment into the knee one week after performing meniscus-removal surgery, called a partial meniscectomy.

Performed in a doctor’s office, the knee injection contains either Chondrogen or a placebo; neither patients nor the surgeons will know which injection a patient has received. One third of the participants will receive Chondrogen at a higher dosage, while another third will receive Chondrogen at a lower dosage and the final third will receive the placebo.

The surgeons then will regularly follow up on patients’ progress using magnetic resonance imaging; patients also will receive the usual follow-up medication and physical rehabilitation they would ordinarily receive after knee surgery. Later, the results of patients receiving Chondrogen will be compared to those who received a placebo.

All procedures, tests and treatments done for research purposes will be provided free of charge to participants. Expenses for procedures, tests and treatments done for normal medical care related to the partial meniscectomy will be billed to patients or their insurance provider, just as they would if patients were not in the trial.

Chondrogen is an investigational product created by Osiris Therapeutics Inc., based in Baltimore.

The formulation of mesenchymal stem cells is produced in a controlled setting and tested for possible infectious agents, such as viruses or bacteria, before it may be injected into the knee.

Because they are universally compatible, mesenchymal stem cells do not require tissue-type matching. These stem cells are a sort of “all-purpose” cell researchers believe they have the potential to specialize and become mature cartilage cells.

For more information about the trial at USC and to find out about eligibility requirements, call (800) USC-CARE or (800) 872-2273.