This double-blind, placebo-controlled pilot study evaluated the safety and efficacy of intra-articular injections of allogenic placental mesenchymal stem cells (MSCs) in 20 patients with symptomatic knee osteoarthritis (OA). Participants received either 0.5–0.6 × 10⁸ allogenic placenta-derived MSCs or saline placebo. Over 24 weeks, the MSC group demonstrated significant improvements in
