title: Senescence and quiescence in adipose-derived stromal cells: Effects of human platelet lysate, fetal bovine serum and hypoxia.
abstract: Adipose-derived stromal cells (ASCs) are attractive sources for cell-based therapies. The hypoxic niche of ASCs in vivo implies that cells will benefit from hypoxia during in vitro expansion. Human platelet lysate (hPL) enhances ASC proliferation rates, compared with fetal bovine serum (FBS) at normoxia. However, the low proliferation rates of FBS-expanded ASCs could be signs of senescence or quiescence. We aimed to determine the effects of hypoxia and hPL on the expansion of ASCs and whether FBS-expanded ASCs are senescent or quiescent.
  
  
  
  ASCs expanded in FBS or hPL at normoxia or hypoxia until passage 7 (P7), or in FBS until P5 followed by culture in hPL until P7, were evaluated by proliferation rates, cell cycle analyses, gene expression and β-galactosidase activity.
  
  
  
  hPL at normoxia and hypoxia enhanced proliferation rates and expression of cyclins, and decreased G0/G1 fractions and expression of p21 and p27, compared with FBS. The shift from FBS to hPL enhanced cyclin levels, decreased p21 and p27 levels and tended to decrease G0/G1 fractions.
  
  
  
  Hypoxia does not add to the effect of hPL during ASC expansion with regard to proliferation, cell cycle regulation and expression of cyclins, p21 and p27. hPL rejuvenates FBS-expanded ASCs with regard to cell cycle regulation and expression of cyclins, p21 and p27. This indicates a reversible arrest. Therefore, we conclude that ASCs expanded until P7 are not senescent regardless of culture conditions.
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Rebekka Harary
authors: RH
authors: Søndergaard
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Bjarke
authors: B
authors: Follin
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Lisbeth Drozd
authors: LD
authors: Lund
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Morten
authors: M
authors: Juhl
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Annette
authors: A
authors: Ekblond
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Jens
authors: J
authors: Kastrup
authors: Cardiology Stem Cell Centre, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark. Electronic address: Mandana.haack-soerensen@regionh.dk.
authors: Mandana
authors: M
authors: Haack-Sørensen
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000328:Adult; D000818:Animals; D001792:Blood Platelets / Q000737:chemistry*; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods*; D002453:Cell Cycle; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D016130:Immunophenotyping; D008297:Male; D044967:Serum; D017154:Stromal Cells / Q000166:cytology* / Q000502:physiology; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D016213:Cyclins; D001616:beta-Galactosidase
keywords: adipose-derived stromal cells; clinical therapy; fetal bovine serum; human platelet lysate; hypoxia; quiescence; senescence