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HSS Researchers Launch Clinical Trial to Determine if Popular Stem Cell Therapy Can Protect Damaged Knees from Osteoarthritis

Led by Andreas H. Gomoll, MD, sports medicine surgeon at Hospital for Special Surgery (HSS), the study is looking at the effects on knee function of ReNu, an allograft product composed of human amniotic membrane and cells from the amniotic fluid. Organogenesis, who makes the product, is studying ReNu in a number of orthopedic applications. The use of placental tissue has a long history in clinical medicine, particularly for the treatment of burns, ulcers and other wounds.

In the new study, "Evaluation of the ReNu Amniotic Suspension Allograft after Marrow Stimulation in the Treatment of Osteochondral Defects", Dr. Gomoll and his colleagues will be injecting ReNu into the knees of eight men and women with chondral and osteochondral defects. Osteochondral defects of the knee simultaneously affect both the bone (osteo) and cartilage (chondral) in the joint, while chondral defects only affect the cartilage. These defects can result from an acute sports injury, chronic wear caused by excessive pressure on the joint or other factors such as a genetic predisposition. Over time, these defects can lead to diffuse cartilage damage in the joint, also known as osteoarthritis, a painful, debilitating condition with few effective non-surgical treatment options.

Patients in the pilot study will receive intra-articular injections of ReNu two and four weeks after standard of care arthroscopic surgery to stimulate healing of the defect. During this procedure, surgeons drill tiny holes into the bone at the bottom of the defect to allow blood cells to seep in from the bone marrow below and clot, with the hope that stem cells from the marrow will help produce a new layer of healthy cartilage.

"There are not that many stem cells in the bone marrow, which can compromise the quality of the repair tissue. While microfracture surgery has satisfactory results in the short term, they tend to worsen over time, especially in larger defects," Dr. Gomoll says.

The researchers will follow the patients periodically for the next two years, making assessments of joint pain and function. The primary outcome of the study is any change after one year of treatment in two validated measures that provide researchers with ratings of mobility, pain, ability to perform activities of daily life and other important aspects of joint function.

Secondary outcomes of the trial are changes in knee pain and function both at the one-year mark and after two years of treatment.

Patients in the trial will be between 18 to 55 years old. The study is open to both men and women; however, because the safety of many medications, including ReNu, on developing fetuses is unclear, participating women must not be pregnant; must be using birth control; be postmenopausal; have been surgically sterilized; or be sexually abstinent.  

Ideally, Dr. Gomoll says, the factors contained in ReNu will help stimulate the patients’ own stem cells. And because stem cells have anti-inflammatory properties, they will help create a more hospitable environment for healing.

"The goal is to improve the quality of the new tissue by calming the knee down and giving the patient’s own stem cells from the bone marrow a boost," he says.

In addition, Dr. Gomoll and Dr. Sabrina Strickland (sports medicine surgeon at HSS) just concluded a randomized controlled trial of ReNu for the treatment of knee arthritis.

"Interim 6 month data showed that treatment with Renu resulted in clinically relevant and statistically significant improvements in pain, symptoms and activities of daily living scores as compared to hyaluronic acid and saline," Dr. Gomoll said. At the six-month mark, significantly more patients who received injections of ReNu reported benefit than did those who received either sham injections or conventional care with viscosupplementation injections. If the approach succeeds over time, "it will be one more treatment option we have, especially for patients who are not great candidates for knee replacement"—such as the old and infirm, but even more importantly young, healthy people who worry that they will lose mobility with the artificial joint.

Organogenesis, based in Canton, Mass., provided funding for both studies.