title: Nanog maintains human chondrocyte phenotype and function in vitro.
abstract: Previous work showed that Nanog, a homeobox family transcription factor, maintains embryonic stem cell pluripotency, suggesting that it has a role in stabilizing cell phenotype. Human chondrocytes lose their phenotype and dedifferentiate after relatively few passages in culture, changes that may limit their value in restoring damaged articular cartilage. We hypothesized that Nanog could stabilize the phenotype of cultured human chondrocytes in long-term monolayer cultures. To test this hypothesis, the human Nanog gene was stably transduced into human chondrocytes using a retroviral vector. Chondrocyte-specific gene expression (collagen type II, aggrecan, cartilage link protein, and Sox9) was measured by reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR in monolayer cultured chondrocytes transduced with Nanog and in control chondrocytes transduced with empty vector. In vitro cartilage matrix protein formation by Nanog-transduced and control cells was compared using Safranin-O and immunofluorescence stains. We found that after 25 passages, Nanog-transduced chondrocytes maintained significantly higher expression of collagen type II, aggrecan, and cartilage link protein genes than controls. Under chondrogenic conditions, Nanog-transduced cells produced significantly more cartilage-specific matrix than control cells. These findings support the hypothesis that Nanog maintains the human chondrocyte phenotype and function after long-term monolayer culture. Preservation of the chondrocyte phenotype may improve the ability of cultured chondrocytes to repair or restore articular cartilage.
authors.affiliation: Department of Orthopaedics and Rehabilitation, 1182 ML, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242, USA.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zheng
authors.forename: Francoise
authors.initials: F
authors.lastname: Gourronc
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Buckwalter
authors.forename: James A
authors.initials: JA
authors.lastname: Martin
mesh_terms: D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D064236:Cartilage Oligomeric Matrix Protein; D054337:Cell Dedifferentiation / Q000235:genetics*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006023:Glycoproteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D064235:Matrilin Proteins; D000071317:Nanog Homeobox Protein; D010641:Phenotype; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D012190:Retroviridae; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic; D000099249:Proteoglycan Link Protein
chemical_list: D053674:Aggrecans; D015415:Biomarkers; D064236:Cartilage Oligomeric Matrix Protein; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D018398:Homeodomain Proteins; D064235:Matrilin Proteins; D000071317:Nanog Homeobox Protein; D011509:Proteoglycans; D055758:SOX9 Transcription Factor; D000099249:Proteoglycan Link Protein; C508319:ACAN protein, human; C486780:NANOG protein, human; C527932:SOX9 protein, human; C577553:TSP5 protein, human