This Phase I/II randomized controlled trial assessed the safety and efficacy of intra-articular injections of umbilical cord-derived mesenchymal stromal cells (UC-MSCs) in patients with symptomatic knee osteoarthritis (OA). Participants were randomized into three groups: hyaluronic acid (HA) injections at baseline and 6 months (n=8), a single UC-MSC dose at baseline