Role of the Calcified Cartilage Layer of an Integrated Tri-layered Silk Fibroin Scaffold Used to Regenerate Osteochondral Defects in Rabbit Knees

The repair of osteochondral defects (OCDs) remains challenging given the complexity of native osteochondral tissue and the limited self-repair capacity of cartilage. Osteochondral tissue engineering is a promising strategy. Here, we fabricated a biomimetic osteochondral scaffold using silk fibroin (SF) and hydroxyapatite (HA) including a calcified cartilage layer (CCL). We studied the role played by the CCL in terms of cell viability in vivo. We established osteochondral defects in rabbit knees to investigate the effects of CCL-containing scaffolds with or without adipose tissue-derived stem cells (ADSCs). We evaluated osteochondral tissue regeneration by calculating gross observational scores, via histological and immunohistochemical assessments, by performing quantitative biochemical and biomechanical analyses of new osteochondral tissue, and via micro-computed tomography (mCT) of new bone at 4, 8, and 12 weeks after surgery. In terms of surface roughness and integrity, the CCL+ADSCs group was better th...