Modulatory effect of three cartilaginous niches on cartilage regeneration from different chondrocyte sources in a goat model.

The body has evolved three types of cartilage: hyaline, elastic, and fibrocartilage. Modern tissue engineering techniques can harvest different types of chondrocytes, expand them in vitro, and use them to repair various cartilage defects. However, the modulatory effect of different cartilaginous niches on the type of regenerated cartilage after the implantation of chondrocytes from different origins remains unknown. In this study, three typical types of cartilage-auricular (elastic cartilage), articular (hyaline cartilage), and meniscus (fibrocartilage)-were investigated. Chondrocytes derived from these cartilages were mixed with Pluronic gel and implanted into three different cartilaginous niches for one month using a goat model. Our results demonstrated that in the articular cartilage environment, regenerated cartilage from auricular chondrocytes lost elastin expression, and cartilage from meniscus chondrocytes lacked a fibrous structure, showing reduced type I collagen and increased type II collagen expression, all resembling a hyaline cartilage-like structure. In the auricular cartilage environment, regenerated cartilage from articular chondrocytes did not express elastin, maintaining a hyaline cartilage-like structure, while fibrocartilage chondrocytes failed to form regenerated cartilage. In the fibrocartilage environment, regenerated cartilage from auricular and meniscus chondrocytes did not exhibit a fibrous structure, with weak type I collagen expression and positive type II collagen expression. Regenerated cartilage from auricular chondrocytes did not express elastin and did not transform into fibrocartilage. This study provides valuable insights into how different cartilaginous niches influence the characteristics of regenerated cartilage, offering potential implications for improving cartilage repair strategies in tissue engineering.