Also effective for use in treating chronic OA pain are oral drugs like duloxetine, Dr. Hochberg said, and among opioids, tramadol. Tramadol carries the risk of both minor and major adverse effects, including dependence, he said. “If you’re going to use tramadol, you start low and increase the dose slowly to ensure your patient tolerates the therapy,” he noted. Opioids other than tramadol should be avoided in OA due to adverse effects, except in patients who are either unwilling to undergo total joint arthroplasty or have contraindications to the procedures, Dr. Hochberg said.
Stem Cell Therapy
Stem cell therapy may be one potential way to restore damaged cartilage and even bone lesions in OA-affected joints, said Rocky Tuan, PhD, director of the Center for Cellular and Molecular Engineering at the University of Pittsburgh Medical Center. Stem cell research in the U.S. has focused on animals, he said. “Unfortunately, there are no specific, longitudinal studies of the efficacy of stem cell therapy in animals, so it’s tough to make that transition to humans,” he said. There are ethical concerns about using embryonic stem cells, so researchers now focus on applications of multipotent stromal cells, or MSCs, autologous cells that may be harvested from sources like bone marrow or umbilical cord blood.
Active MSCs are potentially very useful for OA, said Dr. Tuan. “A stem cell cannot just sit around and be a stem cell. They have to get up and do something!” he joked. MSCs differentiate into other cells like osteoblasts and chondrocytes that may be used to replace OA-damaged tissues, said Dr. Tuan.
MSCs are effective at making new cartilage, but only in 1-mm strands, so Dr. Tuan and his colleagues designed a scaffold to hold stem cells around the joint, he explained. They modified electrospinning, a technique originally designed for the textile industry, to create a scaffold of polymer nanofibers that resembles the cartilage structures within knees. “The cells love this. The cells are sprayed in and are quite happy to latch onto the fibers,” he said. They tested the technique on a miniature pig’s deteriorated knee joint. “It looks promising. We were able to grow cartilage, put it in the knee, and repair the defect,” he said. Dr. Tuan also described the fabrication of an MSC-based osteochondral construct to repair a damaged knee joint in a miniature pig. The joint had an 8-mm lesion in the femoral head, which the researchers filled with a gelatin-based hydrogel that was then illuminated using a dentist’s light. Dr. Tuan showed stained images of the construct after three days that illustrated the viability of MSCs in this application.