Combination of Mesenchymal Stem Cells, Cartilage Pellet and Bioscaffold Supported Cartilage Regeneration of a Full Thickness Articular Surface Defect in Rabbits

BACKGROUND: Mesenchymal stem cells (MSCs) and/or biological scaffolds have been used to regenerate articular cartilage with variable success. In the present study we evaluated cartilage regeneration using a combination of bone marrow (BM)-MSCs, Hyalofast TM and/or native cartilage tissue following full thickness surgical cartilage defect in rabbits. METHODS: Full-thickness surgical ablation of the medial-tibial cartilage was performed in New Zealand white (NZW) rabbits. Control rabbits (Group-I) received no treatment; Animals in other groups were treated as follows. Group-II: BM-MSCs (1 × 10 6 cells) + Hyalofast TM ; Group-III: BMMSCs (1 × 10 6 cells) + cartilage pellet (CP); and Group-IV: BM-MSCs (1 × 10 6 cells) + Hyalofast TM + CP. Animals were sacrificed at 12 weeks and cartilage regeneration analyzed using histopathology, International Cartilage Repair Society (ICRS-II) score, magnetic resonance observation of cartilage repair tissue (MOCART) score and biomechanical studies. RESULTS: Gross images showed good tissue repair (Groups IV > III > Group II) and histology demonstrated intact superficial layer, normal chondrocyte arrangement, tidemark and cartilage matrix staining (Groups III and IV) compared to the untreated control (Group I) respectively. ICRS-II score was 52.5, 65.0, 66 and 75% (Groups I–IV) and the MOCART score was 50.0, 73.75 and 76.25 (Groups II–IV) respectively. Biomechanical properties of the regenerated cartilage tissue in Group IV closed resembled that of a normal cartilage. CONCLUSION: Hyalofast TM together with BM-MSCs and CP led to efficient cartilage regeneration following full thickness surgical ablation of tibial articular cartilage in vivo in rabbits. Presence of hyaluronic acid in the scaffold and native microenvironment cues probably facilitated differentiation and integration of BM-MSCs.