[Indirect coculture of human infrapatellar fat pad-derived stem cells with osteoarthritic chondrocytes induces their chondrogenesis].

Objective: To promote phenotype recovery of osteoarthritic articular chondrocytes( OACs) and induce chondrogenic differentiation of infrapatellar fat pad-derived stem cells( IPFPSCs) by indirectly coculturing these two types of cells. Methods: The OACs and IPFPSCs were isolated and cultured in vitro. This experiment included single IPFPSCs group,single OACs group,and coculture group. After cells were cultured in vitro with chondrogenic medium for 21 days,the chondrocyte phenotypes were determined by HE staining( cell morphology),Alcian blue staining( glycosaminoglycan content) and immunofluorescence cytochemistry( collagen 1,collagen 2,collagen 3,aggrecan,SOX9). Results: In coculture group,the OACs aggregated into microspheres,and the IPFPSCs were oval in shape. In single culture groups,the OACs were less aggregated and the spheres were smaller; and the IPFPSCs were spindle in shape. HE staining showed that,in the coculture group,the nuclei of OACs spheres were dark,and the IPFPSCs were rich in cytoplasm; while in single culture groups,the nuclei of OAC spheres were less dark,and the IPFPSCs were less stained compared with the coculture group. Alcian blue staining indicated that glycosaminoglycan content was higher in the coculture group than in single culture groups. Immunofluorescent staining showed that the intensity of chondrogenic markers( collagen 2,aggrecan,and SOX9)was stronger,while the intensity of collagen 1 and collagen 10 was weaker in the coculture group as compared with single culture groups. Conclusion: The indirect coculture of IPFPSCs with OACs can contribute to the phenotype recovery of OACs and induce the chondrogenic differentiation of IPFPSCs.