title: Long term culture of mesenchymal stem cells in hypoxia promotes a genetic program maintaining their undifferentiated and multipotent status.
abstract: BACKGROUND
  In the bone marrow, hematopietic and mesenchymal stem cells form a unique niche in which the oxygen tension is low. Hypoxia may have a role in maintaining stem cell fate, self renewal and multipotency. However, whereas most studies addressed the effect of transient in vitro exposure of MSC to hypoxia, permanent culture under hypoxia should reflect the better physiological conditions.
  
  
  RESULTS
  Morphologic studies, differentiation and transcriptional profiling experiments were performed on MSC cultured in normoxia (21% O2) versus hypoxia (5% O2) for up to passage 2. Cells at passage 0 and at passage 2 were compared, and those at passage 0 in hypoxia generated fewer and smaller colonies than in normoxia. In parallel, MSC displayed (>4 fold) inhibition of genes involved in DNA metabolism, cell cycle progression and chromosome cohesion whereas transcripts involved in adhesion and metabolism (CD93, ESAM, VWF, PLVAP, ANGPT2, LEP, TCF1) were stimulated. Compared to normoxic cells, hypoxic cells were morphologically undifferentiated and contained less mitochondrias. After this lag phase, cells at passage 2 in hypoxia outgrew the cells cultured in normoxia and displayed an enhanced expression of genes (4-60 fold) involved in extracellular matrix assembly (SMOC2), neural and muscle development (NOG, GPR56, SNTG2, LAMA) and epithelial development (DMKN). This group described herein for the first time was assigned by the Gene Ontology program to "plasticity".
  
  
  CONCLUSIONS
  The duration of hypoxemia is a critical parameter in the differentiation capacity of MSC. Even in growth promoting conditions, hypoxia enhanced a genetic program that maintained the cells undifferentiated and multipotent. This condition may better reflect the in vivo gene signature of MSC, with potential implications in regenerative medicine.
authors: Nancy University Medical School (EA 4369) and School of Surgery (NT), 54500 Vandœuvre-lès-Nancy, France.
authors: Leticia
authors: L
authors: Basciano
authors: Christophe
authors: C
authors: Nemos
authors: Bernard
authors: B
authors: Foliguet
authors: Natalia
authors: N
authors: de Isla
authors: Marcelo
authors: M
authors: de Carvalho
authors: Nguyen
authors: N
authors: Tran
authors: Ali
authors: A
authors: Dalloul
mesh_terms: D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D005434:Flow Cytometry; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D008854:Microscopy, Electron; D039902:Multipotent Stem Cells / Q000166:cytology* / Q000378:metabolism; D057905:Stem Cell Research