Do stem cell injections into the joint space regenerate cartilage?

Stem Cell Injections for Cartilage Regeneration in Osteoarthritis: Current Evidence

Based on current high-quality evidence, stem cell injections are not recommended for cartilage regeneration in osteoarthritis as there is insufficient evidence proving their efficacy in regenerating cartilage and significant concerns regarding standardization of preparations. 1

Current Guidelines on Stem Cell Therapy for Osteoarthritis

Recommendations Against Use

• The 2020 American College of Rheumatology/Arthritis Foundation guidelines strongly recommend against stem cell injections for knee and/or hip osteoarthritis due to concerns regarding heterogeneity and lack of standardization in available preparations and techniques 1

• The 2020 VA/DoD Clinical Practice Guideline for Non-Surgical Management of Hip & Knee Osteoarthritis similarly does not support the use of stem cell injections, citing insufficient evidence for their efficacy in cartilage regeneration 1

• The American Academy of Orthopaedic Surgeons (AAOS) consensus recommendations from 2019 emphasize that the term "stem cell" has been overused to describe uncharacterized minimally manipulated cell preparations and tissue-derived culture-expanded cell populations 1

Concerns About Current Stem Cell Therapies

• There is significant heterogeneity in stem cell preparations used clinically, with no standardized approach to:

  • Cell source (bone marrow, adipose tissue, etc.)
  • Processing techniques
  • Concentration of actual stem cells in injections
  • Delivery methods 1

• True stem cells are defined by three minimum characteristics:

  1. Capable of division and self-renewal for long periods
  2. Unspecialized
  3. Ability to give rise to specialized cell types 1

• Most current "stem cell" preparations used clinically are actually minimally manipulated autologous cell preparations with variable composition and an unknown concentration of actual stem cells 1

Evidence on Efficacy and Safety

Limited Evidence of Benefit

• A 2025 Cochrane systematic review found that compared to placebo injections, stem cell injections may slightly improve pain and function up to six months after treatment (low certainty evidence) 2

• However, the same review found uncertain effects on quality of life or structural progression in the knee (measured by radiographic appearance) 2

• The source, method of preparation, and dose of stem cells varied significantly across studies, limiting the ability to draw firm conclusions 2

Safety Concerns

• There is uncertainty regarding the safety profile of stem cell injections 2

• While serious adverse events were infrequently reported in clinical trials, all invasive joint procedures carry risks including infection 2

• The long-term risks related to the use of a therapy with the theoretical capacity to promote cell growth remain unknown 2

Current Research Status

• While laboratory and animal studies show potential for cartilage repair using stem cells, human clinical evidence remains limited 3, 4

• Case reports have shown some evidence of cartilage regeneration following stem cell therapy, but with limitations:

  • A case report showed areas of hyaline-like cartilage after stem cell treatment, but the patient required total hip arthroplasty 18 months later due to symptom recurrence 4

• Current research is focusing on improving stem cell therapies through:

  • Directing differentiation of mesenchymal stem cells toward chondrogenesis 5
  • Enhancing cartilage-targeting ability of stem cells 5
  • Gene therapy approaches to stimulate chondrogenic processes 6

Conclusion for Clinical Practice

• Despite theoretical potential and ongoing research, current evidence does not support the use of stem cell injections for cartilage regeneration in osteoarthritis 1, 2

• Patients should be informed about the lack of standardization in stem cell preparations and the limited evidence for efficacy in cartilage regeneration 1

• For patients with osteoarthritis seeking treatment, clinicians should recommend evidence-based interventions according to established guidelines, such as exercise, weight management, and conventional pharmacological approaches 1