Quick answer
A 2026 meta-analysis of 28 randomized trials found that mesenchymal stem cell injections were associated with less pain and better function on several scales compared with control injections, but MRI did not show a consistent effect on cartilage structure. The evidence points to modest symptom relief.
The question
Can injections of mesenchymal stem cells into the knee reduce the pain of osteoarthritis? Many trials have tested it, with different products and designs. Two of the most useful sources are summarized here.
28 randomized trials, pooled
The 2026 meta-analysis in Clinical Rheumatology found less pain and better function in daily activities and sport than with control injections. It did not find a consistent change in cartilage on MRI, and local reactions were more frequent.
A placebo-controlled trial
In a phase IIb trial, a single injection of stem cells from the patients' own fat improved pain and function at 6 months, while the saline group did not change significantly.
What it means for you
- The realistic expectation is symptom relief, not new cartilage.
- Exercise, physical therapy and weight management remain the foundation.
- See how we approach it in stem cells for knee pain.
Studies cited
Awad G, et al. Clinical Rheumatology
Efficacy and safety of intra-articular mesenchymal stem cell-based therapies in knee osteoarthritis: A systematic review and meta-analysis of randomized controlled trials
Reported result: Mesenchymal stem cell therapies improved pain versus controls (visual analogue scale, mean difference −1.67) and function on several KOOS domains (daily activities +12.84; sport +11.76; symptoms +15.16). No significant differences in WOMAC or in cartilage structure on MRI. More injection-site pain (RR 2.04) and joint swelling (RR 3.39).
Lee WS, et al. Stem Cells Translational Medicine
Intra-Articular Injection of Autologous Adipose Tissue-Derived Mesenchymal Stem Cells for the Treatment of Knee Osteoarthritis: A Phase IIb, Randomized, Placebo-Controlled Clinical Trial
Reported result: A single injection of adipose-derived stem cells was associated with a significant improvement in WOMAC (pain and function) at 6 months; the saline group did not change significantly. No serious adverse events.