FGF2 and dexamethasone increase the production of hyaluronan in two-dimensional culture of elastic cartilage-derived cells: in vitro analyses and in vivo cartilage formation

Elastic cartilage-derived cells cultured two-dimensionally with FGF2 and corticosteroid produce gel-type masses that become mature cartilage when injected into a subcutaneous pocket. This unique method has previously been clinically applied for treatments of nasal augmentation. However, the components of the gel-type mass and the mechanism of its synthesis remain unknown. Here, we have investigated the components of the gel-type mass produced by elastic cartilage-derived cells, and whether this gel-type mass can be produced by using other cell sources or other media. Human elastic cartilage-derived cells from auricular cartilage, hyaline cartilage-derived cells from articular cartilage, and mesenchymal stem cells from synovium were cultured in three media: “redifferentiation medium” containing FGF2 and dexamethasone; “chondrogenic medium” containing bone morphogenetic protein-2, transforming growth factor-β3, and dexamethasone specific for in vitro chondrogenesis of mesenchymal stem cells; control medium. The elastic cartilage-derived cells cultured in redifferentiation medium produced a gelatinous matrix positive for Alcian blue. During culture, the amount of chondroitin 4-sulfate, chondroitin 6-sulfate, and especially hyaluronan increased. However, the expression of RNAs for most chondrogenic genes did not increase. We also reproduced cartilage tissue formation by the injection of elastic cartilage-derived cells with the gelatinous mass into the subcutaneous space of the nude mouse. The synthesis of gelatinous matrix in vitro and the formation of cartilage tissue in vivo could be obtained only for the combination of elastic cartilage-derived cells with redifferentiation medium.