In vivo evaluation of stem cell aggregates on osteochondral regeneration

To date, many osteochondral regenerative approaches have utilized varied combinations of biocompatible materials and cells to engineer cartilage. Even in cell-based approaches, to date, no study has utilized stem cell aggregates alone for regenerating articular cartilage. Thus, the purpose of this study was to evaluate the performance of a novel stem cell-based aggregate approach in a fibrin carrier to regenerate osteochondral defects in the Sprague-Dawley rat trochlear groove model. Two different densities of rat bone marrow mesenchymal stem cell (rBMSC) aggregates were fabricated by the hanging drop technique. At 8 weeks, the cell aggregates supported the defects and served as a catalyst for neo-cartilage synthesis, and the experimental groups may have been beneficial for bone and cartilage regeneration compared to the fibrin-only control and sham groups, as evidenced by histological assessment. The cell density of rBMSC aggregates may thus directly impact chondrogenesis. The usage of cell aggregates with fibrin as a cell-based technology is a promising and translational new treatment strategy for repair of cartilage defects. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1606-1616, 2017.