The newest method of treating osteoarthritis using mesenchymal stem cell injection is presented

A study by scientists from Japan showed that intra-articular injections of mesenchymal stem cells (MSCs) stimulate the expression of several genes that stop the progression of osteoarthritis (OA).

Ichiro Sekiya, MD from Tokyo University of Medicine and Dentistry, explained the mechanism of action of this treatment.

“Synovial MSCs have a high chondrogenic potential”, – he said in his presentation at the OARSI World Congress 2021 virtual meeting. “Synovium itself has a high regenerative potential. MRI analysis showed that synovial MSC injections stop cartilage destruction in patients with progressive OA”.

The synovium is the inner layer of the articular capsule, which lines the surface of the joint cavity and ligament, except for the cartilaginous areas. The synovium and synovial fluid are rich sources of mesenchymal stem cells.

For the study, Sekiya’s group received samples of bone marrow, synovium, periosteum, adipose tissue, and skeletal muscle from people who had undergone anterior cruciate ligament reconstruction. Scientists have noticed that after treatment with enzymes, synovial cells multiply and form colonies. According to Sekiya, about 50 million mesenchymal stem cells can be obtained from the synovium within two weeks.

In preclinical studies, injections of human MSCs into the knee joint of rats inhibited cartilage degeneration and progression of OA. Genetic analysis showed that intra-articular expression of proteoglycan-4 (PRG4), bone morphogenetic protein-2 (BMP-2), BMP-6, and TNF-stimulated synovial protein of gene 6 (TSG-6) were significantly increased after injections.

Sekiya explained the proposed mechanism of action of the new treatment and the important role of these genes:

“Synovial MSCs injected into the knee joint mostly migrated to the synovium and act as anti-inflammatory agent through TSG-6 expression, as a lubrication agent through PRG-4 expression and incur cartilage matrix synthesis by BMP-6 expression”, – he said. “Consequently, exogenous MSCs can inhibit the progression of OA.”

According to Dr. Sekiya’s report, among 14 clinical reports from experimental groups documenting this method, pain relief was recorded in all studies. In addition, there were no cases of synovial fibrosis.

The latest findings from Sekiya’s group came from a study of the efficacy of mesenchymal stem cell injections in eight patients with osteoarthritis.

The primary goal was to assess the number of patients who would demonstrate an improvement in the predicted ratio of cartilage area at the femoral posteromedial region 30 weeks before and 30 weeks after synovial MSC injections. An increase in cartilage thickness of more than 1.5 mm was considered a positive result. Two injections were given 15 weeks apart.

“We only included patients who had cartilage loss immediately prior to injection”, – he said.

The results showed that after the first injection, seven patients reached the primary endpoint.

“Most patients showed no further improvement beyond the effects of the first injection”, – Sekiya said. “A second injection might not be necessary in a 30-week period.”

Side effects in most patients manifested themselves in knee pain for a week immediately after the procedure. There was also a feeling of itching on the hands 1 week after the first injection.

“Fully automated 3D MRI analysis showed that synovial mesenchymal stem cells injections suppressed cartilage loss in patients with progressive OA”, – Sekiya concluded.