Initial safety outcomes of adipose-derived mesenchymal stem cell for rotator cuff tear: A 3-year pilot trial

Background: Rotator cuff injuries are the underlying cause of shoulder pain in 65-70 % of the patients over the age of 50. A novel therapeutic approach is stem cell therapy, which promises to heal. This study represents one of the first long-term safety evaluations of autologous adipose-derived mesenchymal stem cells (MSCs) in human subjects with total rotator cuff tear, with a specific focus on potential adverse effects. Methods: This study was designed as a pilot safety phase within a broader clinical trial framework. Ten patients with full-thickness rotator cuff tears were enrolled. Autologous mesenchymal stem cells (MSCs), derived from adipose tissue, were injected directly into the torn tendons under ultrasound guidance. Patients were monitored over a 36-month period to assess safety outcomes. These included complete blood count (CBC), inflammatory markers-erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)-radiological imaging (X-ray and MRI), pain assessment via visual analog scale (VAS), and functional status through validated questionnaires. Results: No systemic or local adverse events were reported during the 36-month follow-up, indicating a favorable safety profile. The CBC parameters after three years compared to the baseline measurement: hemoglobin [mean = 13.92 (SD = 1.32) vs. 13.85 (1.34)], red blood cells [mean = 4.97 (SD = 0.31) vs. 5.11 (0.31)], white blood cells [mean = 6.05 (SD = 2.06) vs. 6.01 (1.70)], platelets [mean = 248.8 (SD = 2.76) vs. 246.9 (2.50)]. The inflammatory markers were also within the normal range as following: ESR [mean = 7 (SD = 1.22) vs. 6.4 (2.48)] and CRP [mean = 0.2 (SD = 0.70) vs. 0.3 (SD = 0.89)]. Pain intensity and functional status improved compared to baseline: VAS [3.6 (SD = 1.17) vs 8.5 (1.93)], WORC [34.17 (SD = 3.31) vs 47.53 (SD = 2.56)], DASH [32.95 (SD = 2.45) vs 50.71 (SD = 4.34)].The shoulder X-ray and MRI did not show any significant pathology in the soft or bony tissues of the shoulder joint over the follow-ups. Conclusion: Injection of autologous MSCs derived from adipose tissue is safe in treating total rotator cuff tear. These findings support the initiation of larger-scale trials to further investigate the therapeutic potential and efficacy of MSCs in tendon regeneration.