Introduction: Articular cartilage is an avascular, aneural, and alymphatic tissue that has limited capacity to regenerate. Numerous techniques have been employed to repair or regenerate; however, the success rate varies. In fact, most of them result in the formation of fibrocartilage, not hyaline cartilage. The future of treating cartilage defects lies in providing biologic solutions through cartilage regeneration. Mesenchymal stem cells (MSCs) represent a promising therapy for cartilage regeneration. These cells secrete factors that enhance cartilage repair. In this study, the effects of intra-articular injection of human umbilical cord MSC (hUC-MSC) secretome on cartilage damage was studied in a sheep model.

Methods: Standardized rectangular (5x5 mm) full-thickness chondral defects were created in the lateral femoral condyle of 15 adult sheep and debrided down to the subchondral bone plate. Three treatment groups were tested: 4 microfracture perforations using 1.0mm diameter awls (group 1), intra-articular injection of hUC-MSC secretome (group 2), and combination of microfracture and intra-articular injection of hUC-MSC secretome (group 3). Osteochondral repair was assessed at 6 months in vivo using established macroscopic and histological analyses.

Results:  Macroscopically, application of combined therapy shows significant improvement of cartilage repair compared to microfracture alone (p=0.004). Microscopically, the application of combined therapy shows significant improvement of cartilage repair compared to secretome injection alone (p=0.031)

Conclusion: Microfracture combined with injection of hUCB-MSCs secretome could be an effective alternative for repairing articular cartilage defects in vivo.

Standardized rectangular (5x5 mm) full-thickness chondral defects were created in the lateral femoral condyle of 15 adult sheep and debrided down to the subchondral bone plate. Three treatment groups were tested: 4 microfracture perforations using 1.0mm diameter awls (group 1), intra-articular injection of hUC-MSC secretome (group 2), and combination of microfracture and intra-articular injection of hUC-MSC secretome (group 3). Osteochondral repair was assessed at 6 months in vivo using established macroscopic and histological analyses.