Comparison of biochemical characteristics of cultured fibrochondrocytes isolated from the inner and outer regions of human meniscus.

In order to evaluate the ability of fibrochondrocytes to synthesize collagen and proteoglycan, human medial meniscal cells were cultured in a monolayer. Meniscal cells were prepared from the two regions (outer 1/3 and inner 2/3) in consideration of the difference in vascular supply, and articular chondrocytes were also obtained from the same knee joint. Regarding total collagen synthesis, regional differences were not found, but age-related differences were found in human medial meniscus. In contrast, proteoglycan synthesis revealed significant regional differences; meniscal cells from the inner 2/3 synthesized a greater amount of proteoglycan. After long-term monolayer culturing, proteoglycan synthesis by meniscal cells decreased in a time-dependent manner, and morphological changes to fibroblast-like cells were found. In the presence of transforming growth factor (TGF)-beta, proteoglycan synthesis increased in a dose-dependent manner. These findings suggest that the inner regions of the human meniscus contain cells with a chondrocytic phenotype.