A Study On Indirect Coculture Of Human Infrapatellar Fat Pad-derived Stem Cells With Osteoarthritic Chondrocytes

Objective The aim of this study was to promote phenotype recovery of osteoarthritic articular chondrocytes(OACs)and induce chondrogeneic differentiation of infrapatellar fat pad-derived stem cells(IPFPSCs)by indirectly coculturing these two types of cell.Methods The OACs and IPFPSCs were isolated and cultured in vitro.This experiment was divided into single IPFPSCs group,single OACs group,and coculture group.After cells were cultured in vitro with chondrogenic medium for 21 days,the chondrocyte phenotype was determined by HE staining(cell morphology),Alcian blue stainings(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 individual groups,the OACs were less aggregated and the spheres were smaller;while the IPFPSCs were spindle in shape.HE staining showed that,in coculture group,the nuclei of OACs spheres were dark,and the IPFPSCs were rich in cytoplasm;while in individual groups,the nuclei of OAC spheres were less dark,and the IPFPSCs were less stained compared to coculture group.Alcian blue staining indicated that glycosaminoglycan content was higher in coculture group than that in individual groups.Immunofluorescent staining showed that in coculture group the intensity of chondrogenic markers(collagen 2,aggrecan,and SOX9)was strong,while the intensity of collagen 1 and collagen 10 was weak;in individual groups,vice versa.Conclusion The indirect coculture of IPFPSCs with OACs can contribute to the phenotype recovery of OACs and induce the chondrogenic differentiation of IPFPSCs.