Restoration of a large osteochondral defect of the knee using a composite of umbilical cord blood-derived mesenchymal stem cells and hyaluronic acid hydrogel: a case report with a 5-year follow-up

Background: The treatment of articular cartilage defects is a therapeutic challenge for orthopaedic surgeons. Furthermore, large osteochondral defects needs restoration of the underlying bone for sufficient biomechanical characteristics as well as the overlying cartilage. Case presentation: A symptomatic large osteochondral defect in the knee joint was restored using a composite of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) 0.5 x 10(7)/ml and 4% hyaluronic acid (HA) hydrogel. Significant improvements in pain and function of the knee joint were identified by the evaluation at 12 months after surgery. A hyaline-like cartilage completely filled the defect and was congruent with the surrounding normal cartilage as revealed by magnetic resonance imaging (MRI), a second-look arthroscopy and histological assessment. The improved clinical outcomes maintained until 5.5 years. MRI also showed the maintenance of the restored bony and cartilaginous tissues. Conclusion: This case report suggests that the composite of allogeneic UCB-MSCs and HA hydrogel can be considered a safe and effective treatment option for large osteochondral defects of the knee.