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In this study, we investigate the effects of treatment with layered chondrocyte sheets and synovial cell transplantation. An osteochondral defect was created of 48 Japanese white rabbits. In order to determine the effects of treatment, the following 6 groups were produced: (A) synovial cells (1.8 × 10(6) cells), (B)layered chondrocyte sheets (1.7 × 10(6) cells), (C) synovial cells (3.0 × 10(5) cells) + layered chondrocyte sheets, (D)synovial cells (6.0 × 10(5) cells) + layered chondrocyte sheets, (E)synovial cells (1.2 × 10(6) cells) + layered chondrocyte sheets, (F) osteochondral defect. Layered chondrocyte sheets and synovial cells were transplanted, sacrificed four and 12 weeks postoperatively. An incapacitance tester (Linton) was used to find trends in the weight distribution ratio of the damaged limbs after surgery. Sections were stained with Safranin-O. Repair sites were evaluated using ICRS grading system. In groups (A) to (E), the damaged limb weight distribution ratio had improved. The repair tissue stained positively with Safranin-O. Four and 12 weeks after surgery, groups (A) to (E) exhibited significantly higher scores than group (F), and groups (D) and (E) exhibited significantly higher scores than groups (A) and (B). This suggests the efficacy of combining layered chondrocyte sheets with synovial cells., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Lacking a blood supply and having a low cellular density, articular cartilage has a minimal ability for self-repair. Therefore, wide-ranging cartilage damage rarely resolves spontaneously. Cartilage damage is typically treated by chondrocyte transplantation, mosaicplasty or microfracture. Recent advances in tissue engineering have prompted research on techniques to repair articular cartilage damage using a variety of transplanted cells. We studied the repair and regeneration of cartilage damage using layered chondrocyte sheets prepared on a temperature-responsive culture dish. We previously reported achieving robust tissue repair when covering only the surface layer with layered chondrocyte sheets when researching partial-thickness defects in the articular cartilage of domestic rabbits. The present study was an experiment on the repair and regeneration of articular cartilage in a minipig model of full-thickness defects. Good safranin-O staining and integration with surrounding tissues was achieved in animals transplanted with layered chondrocyte sheets. However, tissue having poor safranin-O staining-not noted in the domestic rabbit experiments-was identified in some of the animals, and the subchondral bone was poorly repaired in these. Thus, although layered chondrocyte sheets facilitate articular cartilage repair, further investigations into appropriate animal models and culture and transplant conditions are required., (Copyright © 2012 Elsevier Ltd. All rights reserved.)