title: Downregulation of APE1/Ref-1 is involved in the senescence of mesenchymal stem cells.
abstract: The senescence of human mesenchymal stem cells (hMSCs) causes disruption of tissue and organ maintenance, and is thus an obstacle to stem cell-based therapies for disease. Although some researchers have studied changes in the characteristics of hMSCs (decreases in differentiation ability and self-renewal), comparing young and old ages, the mechanisms of stem cell senescence have not yet been defined. In this study, we developed a growth curve for human bone marrow derived MSCs (hBMSCs) which changes into a hyperbolic state after passage number 7. Senescence associated beta-galactosidase (SA beta-gal) staining of hBMSCs showed 10% in passage 9 and 45% in passage 11. We detected an increase in endogenous superoxide levels during senescence that correlated with senescence markers (SA beta-gal, hyperbolic growth curve). Interestingly, even though endogenous superoxide increased in a replicative senescence model, the expression of APE1/Ref-1, which is sensitive to intracellular redox state, decreased. These effects were confirmed in a stress-induced senescence model by exogenous treatment with H(2)O(2). This change is related to the p53 activity that negatively regulates APE1/Ref-1. p21 expression levels, which represent p53 activity, were transiently increased in passage 9, meaning that they correlated with the expression of APE1/Ref-1. Overexpression of APE1/Ref-1 suppressed superoxide production and decreased SA beta-gal in hBMSCs. In conclusion, intracellular superoxide accumulation appears to be the main cause of the senescence of hBMSCs, and overexpression of APE1/Ref-1 can rescue cells from the senescence phenotype. Maintaining characteristics of hBMSCs by regulating intracellular reactive oxygen species production can contribute to tissue regeneration and to improved cell therapy.
authors.affiliation: Department of Biochemistry, College of Medicine, Chungnam National University, Teajeon, South Korea.
authors.forename: Jun-Young
authors.initials: JY
authors.lastname: Heo
authors.forename: Kaipeng
authors.initials: K
authors.lastname: Jing
authors.forename: Kyoung-Sub
authors.initials: KS
authors.lastname: Song
authors.forename: Kang-Sik
authors.initials: KS
authors.lastname: Seo
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Park
authors.forename: Jong-Seok
authors.initials: JS
authors.lastname: Kim
authors.forename: Yeon-Joo
authors.initials: YJ
authors.lastname: Jung
authors.forename: Gang-Min
authors.initials: GM
authors.lastname: Hur
authors.forename: Deog-Yeon
authors.initials: DY
authors.lastname: Jo
authors.forename: Gi-Ryang
authors.initials: GR
authors.lastname: Kweon
authors.forename: Wan-Hee
authors.initials: WH
authors.lastname: Yoon
authors.forename: Kyu
authors.initials: K
authors.lastname: Lim
authors.forename: Byung-Doo
authors.initials: BD
authors.lastname: Hwang
authors.forename: Byeong Hwa
authors.initials: BH
authors.lastname: Jeon
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Park
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D016922:Cellular Senescence / Q000502:physiology*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000096:biosynthesis*; D015536:Down-Regulation; D005434:Flow Cytometry; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D018613:Microscopy, Confocal; D018384:Oxidative Stress / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism
chemical_list: D013481:Superoxides; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase