Mesenchymal stromal cell transplantation may improve pain and increase function in patients with knee osteoarthritis, according to a recent systematic review and meta-analysis published by Xie et al in the Journal of Orthopaedic Research. Investigators explained that although previous studies have explored cell therapy in this patient population, the benefit of stem cell transplantation from different sources has been unclear. In the new analysis, investigators examined the outcomes of 16 randomized controlled trials involving 875 patients with knee osteoarthritis who received stem cell therapy, with the goal of determining the curative effects of different stem cells. After measuring treatment efficacy through the Visual Analog Scale, Lequesne index, Lysholm Knee Scoring Scale, and Western Ontario and McMaster University Osteoarthritis Index, as well as joint injury through the Whole-Organ Magnetic Resonance Imaging Score system, the investigators found that mesenchymal stromal cell transplantation was effective at reducing pain after 3 months. They noted that the most pain relief was attained from adipose- and umbilical cord–derived stem cells. While autologous adipose tissue was more effective at improving pain than allogenic adipose tissue, autologous bone marrow stem cells were not superior to allogenic bone marrow stem cells in terms of pain relief. Additionally, autologous adipose-derived stem cells were capable of recovering knee joint function. The investigators concluded that mesenchymal stromal cell transplantation may be safely and effectively alleviate pain, restore joint function, and mitigate patient trauma in this population.