Safety and efficacy of allogenic placental mesenchymal stem cells for treating knee osteoarthritis: a pilot study.

OBJECTIVE: Knee osteoarthritis (OA) is a common skeletal impairment that can cause many limitations in normal life activities. Stem cell therapy has been studied for decades for its regenerative potency in various diseases. We investigated the safety and efficacy of intra-articular injection of placental mesenchymal stem cells (MSCs) in knee OA healing. METHODS: In this double-blind, placebo-controlled clinical trial, 20 patients with symptomatic knee OA were randomly divided into two groups to receive intra-articular injection of either 0.5-0.6 × 108 allogenic placenta-derived MSCs or normal saline. The visual analogue scale, Knee OA Outcome Score (KOOS) questionnaire, knee flexion range of motion (ROM) and magnetic resonance arthrography were evaluated for 24 weeks post-treatment. Blood laboratory tests were performed before and 2 weeks after treatment. RESULTS: Four patients in the MSC group showed mild effusion and increased local pain, which resolved safely within 48-72 h. In 2 weeks post-injection there was no serious adverse effect and all of the laboratory test results were unchanged. Early after treatment, there was a significant knee ROM improvement and pain reduction (effect size, 1.4). Significant improvements were seen in quality of life, activity of daily living, sport/recreational activity and decreased OA symptoms in the MSC-injected group until 8 weeks (P < 0.05). These clinical improvements were also noted in 24 weeks post-treatment but were not statistically significant. Chondral thickness was improved in about 10% of the total knee joint area in the intervention group in 24 weeks (effect size, 0.3). There was no significant healing in the medial/lateral meniscus or anterior cruciate ligament. There was no internal organ impairment at 24 weeks follow-up. CONCLUSION: Single intra-articular allogenic placental MSC injection in knee OA is safe and can result in clinical improvements in 24 weeks follow-up. TRIAL REGISTRATION NUMBER: IRCT2015101823298N.