title: Comparison of the gene expression profile of undifferentiated human embryonic stem cell lines and differentiating embryoid bodies.
abstract: BACKGROUND
  The identification of molecular pathways of differentiation of embryonic stem cells (hESC) is critical for the development of stem cell based medical therapies. In order to identify biomarkers and potential regulators of the process of differentiation, a high quality microarray containing 16,659 seventy base pair oligonucleotides was used to compare gene expression profiles of undifferentiated hESC lines and differentiating embryoid bodies.
  
  
  RESULTS
  Previously identified "stemness" genes in undifferentiated hESC lines showed down modulation in differentiated cells while expression of several genes was induced as cells differentiated. In addition, a subset of 194 genes showed overexpression of greater than > or = 3 folds in human embryoid bodies (hEB). These included 37 novel and 157 known genes. Gene expression was validated by a variety of techniques including another large scale array, reverse transcription polymerase chain reaction, focused cDNA microarrays, massively parallel signature sequencing (MPSS) analysis and immunocytochemisty. Several novel hEB specific expressed sequence tags (ESTs) were mapped to the human genome database and their expression profile characterized. A hierarchical clustering analysis clearly depicted a distinct difference in gene expression profile among undifferentiated and differentiated hESC and confirmed that microarray analysis could readily distinguish them.
  
  
  CONCLUSIONS
  These results present a detailed characterization of a unique set of genes, which can be used to assess the hESC differentiation.
authors.affiliation: Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA. Bhattacharya@cber.fda.gov
authors.forename: Bhaskar
authors.initials: B
authors.lastname: Bhattacharya
authors.forename: Jingli
authors.initials: J
authors.lastname: Cai
authors.forename: Youngquan
authors.initials: Y
authors.lastname: Luo
authors.forename: Takumi
authors.initials: T
authors.lastname: Miura
authors.forename: Josef
authors.initials: J
authors.lastname: Mejido
authors.forename: Sandii N
authors.initials: SN
authors.lastname: Brimble
authors.forename: Xianmin
authors.initials: X
authors.lastname: Zeng
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Schulz
authors.forename: Mahendra S
authors.initials: MS
authors.lastname: Rao
authors.forename: Raj K
authors.initials: RK
authors.lastname: Puri
mesh_terms: D015415:Biomarkers; D002454:Cell Differentiation / Q000235:genetics*; D016000:Cluster Analysis; D030561:Databases, Nucleic Acid; D004622:Embryo, Mammalian / Q000166:cytology*; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling / Q000379:methods* / Q000592:standards; D005786:Gene Expression Regulation; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D013234:Stem Cells / Q000166:cytology*
chemical_list: D015415:Biomarkers