Articular cartilage is a structure lack of vascular distribution. Once the cartilage is injured or diseased, it is unable to regenerate by itself. Surgical treatments do not effectively heal defects in articular cartilage. Tissue engineering is the most potential solution to this problem. In this study, methoxy poly(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-PCL) and hydroxyapatite at a weight ratio of 2:1 were mixed via fused deposition modeling (FDM) layer by layer to form a solid scaffold. The scaffolds were further infiltrated with glycidyl methacrylate hyaluronic acid loading with 10 ng/mL of Transforming Growth Factor-β1 and photo cross-linked on top of the scaffolds. An in vivo test was performed on the knees of Lanyu miniature pigs for a period of 12 months. The healing process of the osteochondral defects was followed by computer tomography (CT). The defect was fully covered with regenerated tissues in the control pig, while different tissues were grown in the defect of knee of the experimental pig. In the gross anatomy of the cross section, the scaffold remained in the subchondral location, while surface cartilage was regenerated. The cross section of the knees of both the control and experimental pigs were subjected to hematoxylin and eosin staining. The cartilage of the knee in the experimental pig was partially matured, e.g., few chondrocyte cells were enclosed in the lacunae. In the knee of the control pig, the defect was fully grown with fibrocartilage. In another in vivo experiment in a rabbit and a pig, the composite of the TGF-β1-loaded hydrogel and scaffolds was found to regenerate hyaline cartilage. However, scaffolds that remain in the subchondral lesion potentially delay the healing process. Therefore, the structural design of the scaffold should be reconsidered to match the regeneration process of both cartilage and subchondral bone.
Keywords: biomimetic; cartilage; fused deposition modeling; hyaluronic acid; large animal models; poly(ε-caprolactone).