The Effect of Injection of Secretome of Umbilical Cord Mesenchymal Stem Cells in Articular Cartilage Repair in Sheep Model

Introduction: Articular cartilage is an avascular, aneural, and lymphatic tissue with 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 biological solutions through cartilage regeneration. Mesenchymal stem cells (MSCs) represent a promising therapy for cartilage regeneration. These cells secrete factors that enhance cartilage repair. This study studied the effects of intra-articular injection of human umbilical cord MSC (hUC-MSC) secretome on cartilage damage 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 a combination of microfracture and intra-articular injection of hUC-MSC secretome (group 3). The osteochondral repair was assessed at 6 months using an established macroscopic and histological analyses. Results: Macroscopically, combined therapy application shows significant cartilage repair improvement 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.