Fig 1.
Chondrocytes were isolated from rabbit cartilage and proliferated in an RCCS. The cell-matrix constructs gradually formed neocartilage, and each was then embedded into a surgically created wound in the knee.
Fig 2.
Various size bone defects at 3 months.
(A) Self-repair was identified in the 3-mm circular, 3-mm-deep bone defects. Dotted box indicates the defect site. Note the surface disruption. (B) Fibrous cartilage repair with superficial fragmentation was apparent in the 4-mm circular, 3-mm-deep defects. Dotted box indicates the defect site. (C) Incomplete healing with fibrous tissue coverage was observed in the 5-mm circular, 4-mm-deep bone defects. Dotted box indicates the defect site. Note the fibrosis penetrating into the new bone formation region (indicated by arrow). All images: HE staining, magnification 20×.
Fig 3.
Rotating cell culture of chondrocytes for neocartilage constructs.
Chondrocytes cultured in type II/I collagens from different species formed neocartilage constructs at 2 and 4 weeks (HE staining, magnification 200×). GAG expression of neoRBT and neoRAT cartilage at 4 weeks is displayed in the right-most column. Note the moderate GAG accumulation at 4 weeks in both the neoRBT and neoRAT cartilage. GAG accumulation around the lacuna of chondrocytes was observed in both neocartilage types.
Fig 4.
Neocartilage plug implantation.
(A), (B) Neocartilage plugs of diameter 5 mm were implanted into the rabbit condyles. Condyles containing (C) neoRBT and (D) neoRAT cartilage at 3 months after surgery.
Fig 5.
Cartilage regeneration using different neocartilage constructs.
Black arrow in each graph indicates the defect site with or without implantation. In 2 months, less fragmentation and more integration with adjacent tissue were identified in neoRAT cartilage sites (A) compared with neoRBT cartilage sites (B). In 3 months, both (C) neoRAT and (D) neoRBT cartilage groups exhibited hyaline-like cartilage characterized by well-defined chondrocytes. Magnification of the labeled area in (C) and (D) revealed abundant aligned clusters in the (E) neoRAT and (F) neoRBT cartilage. The autograft group showed abundant hyaline-like cartilage penetration at 3 months. Well-defined wound healing was observed in the autograft group (G), whereas a gap was found between the base of the defect and the graft at 3 months in the allograft group (H). The allograft did not integrate with the adjacent normal tissue. In the surgery without implantation control group, the defect was filled with severe fibrosis, no cartilage was found in the defect area, the subchondral bone in the wound was denuded, no union had occurred, and pannus formation was noted in the defect area (I). All images: HE staining, magnification 20×.