title: Expression analysis of human adipose-derived stem cells during in vitro differentiation to an adipocyte lineage.
abstract: BACKGROUND
  Adipose tissue-derived stromal stem cells (ASCs) represent a promising regenerative resource for soft tissue reconstruction. Although autologous grafting of whole fat has long been practiced, a major clinical limitation of this technique is inconsistent long-term graft retention. To understand the changes in cell function during the transition of ASCs into fully mature fat cells, we compared the transcriptome profiles of cultured undifferentiated human primary ASCs under conditions leading to acquisition of a mature adipocyte phenotype.
  
  
  METHODS
  Microarray analysis was performed on total RNA extracted from separate ACS isolates of six human adult females before and after 7 days (7 days: early stage) and 21 days (21 days: late stage) of adipocyte differentiation in vitro. Differential gene expression profiles were determined using Partek Genomics Suite Version 6.4 for analysis of variance (ANOVA) based on time in culture. We also performed unsupervised hierarchical clustering to test for gene expression patterns among the three cell populations. Ingenuity Pathway Analysis was used to determine biologically significant networks and canonical pathways relevant to adipogenesis.
  
  
  RESULTS
  Cells at each stage showed remarkable intra-group consistency of expression profiles while abundant differences were detected across stages and groups. More than 14,000 transcripts were significantly altered during differentiation while ~6000 transcripts were affected between 7 days and 21 days cultures. Setting a cutoff of +/-two-fold change, 1350 transcripts were elevated while 2929 genes were significantly decreased by 7 days. Comparison of early and late stage cultures revealed increased expression of 1107 transcripts while 606 genes showed significantly reduced expression. In addition to confirming differential expression of known markers of adipogenesis (e.g., FABP4, ADIPOQ, PLIN4), multiple genes and signaling pathways not previously known to be involved in regulating adipogenesis were identified (e.g. POSTN, PPP1R1A, FGF11) as potential novel mediators of adipogenesis. Quantitative RT-PCR validated the microarray results.
  
  
  CONCLUSIONS
  ASC maturation into an adipocyte phenotype proceeds from a gene expression program that involves thousands of genes. This is the first study to compare mRNA expression profiles during early and late stage adipogenesis using cultured human primary ASCs from multiple patients.
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.|McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.
authors.forename: Latha
authors.initials: L
authors.lastname: Satish
authors.affiliation: Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Krill-Burger
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.
authors.forename: Phillip H
authors.initials: PH
authors.lastname: Gallo
authors.affiliation: Connecticut College, Department of Biology, New London, CT, USA.
authors.forename: Shelley Des
authors.initials: SD
authors.lastname: Etages
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Philips
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.
authors.forename: Sudheer
authors.initials: S
authors.lastname: Ravuri
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.|McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.
authors.forename: Kacey G
authors.initials: KG
authors.lastname: Marra
authors.affiliation: Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: LaFramboise
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA.|McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kathju
authors.affiliation: Department of Plastic Surgery, University of Pittsburgh Medical Center, 3550 Terrace Street, 6B Scaife Hall, 15261, Pittsburgh, PA, USA. rubipj@upmc.edu.|McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA. rubipj@upmc.edu.
authors.forename: J Peter
authors.initials: JP
authors.lastname: Rubin
mesh_terms: D017667:Adipocytes / Q000166:cytology*; D000273:Adipose Tissue / Q000166:cytology*; D000328:Adult; D053687:Adult Stem Cells / Q000166:cytology*; D002454:Cell Differentiation / Q000235:genetics*; D019070:Cell Lineage / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology
chemical_list: D012333:RNA, Messenger