Mechano-functional assessment of human mesenchymal stem cells grown in three-dimensional hyaluronan-based scaffolds for cartilage tissue engineering

Human mesenchymal stem cells (hMSCs) are an alternative cell source in bioconstruct production for cartilage regeneration, and hyaluronic acid (HA) is a widely-used bioabsorbable scaffold material used for cartilage regeneration. In this work, the aims were to evaluate the mechanical competency of hMSC-seeded HA scaffolds compared with native intact human articular cartilage, and in relation to its cellular properties. Human MSCs were grown under static conditions in HA scaffolds and then tested, in stepwise, stress-relaxation indentation, 7, 14, and 21 days later. Scaffolds at days 14 and 21 showed a significant increase in mechanical measures when compared with day 7 and unseeded scaffold material, but did not achieve the same levels as human cartilage. There was consistent stiffness within the scaffold, with a decreased stiffness around the edge. In vitro culture of hMSC-seeded HA scaffolds over 3 weeks produces a white, solid tissue compared with unseeded constructs. Increased cell proliferation and collagen type II expression were also seen over this period of time. These results demonstrate the competency of the neo-formed cartilage-like tissue in relation to its mechanical and cellular properties, and further, the importance, for future clinical use, of implanting this construct after 14 days of culture.