title: Hydrogen sulfide augments the proliferation and survival of human induced pluripotent stem cell-derived mesenchymal stromal cells through inhibition of BKCa.
abstract: BACKGROUND
  Hydrogen sulfide (H2S) is an endogenously generated gaseous transmitter known for its cytoprotective effect mediated by the PI3K-Akt signaling pathway. Human induced pluripotent stem cell (hiPSC)-derived mesenchymal stromal cells (MSCs), or hiPSC-MSCs, represent an alternative source of MSCs for autologous cell therapy. The big-conductance Ca(2+)-activated outward K(+) currents (BKCa), known to mediate cell proliferation, have been detected in >80% of hiPSC-MSCs. The present study aimed to explore the effect of H2S on survival and proliferation of hiPSC-MSCs and investigate the mediatory role of BKCa.
  
  
  METHODS
  Effects of H2S on proliferation and survival of hiPSC-MSCs were measured by 5-bromo-2-deoxyuridine incorporation, population doubling and cell cycle assays, and by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide assay and 4'-6-diamidino-2-phenylindole staining, respectively. BKCa was recorded by means of the whole-cell patch-clamp technique. The expressions of KCa 1.1 (encoding BKCa) and apoptosis-related genes were measured by reverse transcriptase-polymerase chain reaction. The phosphorylation of Akt was assessed by Western blot analysis.
  
  
  RESULTS
  Exogenously administered NaHS (an H2S donor, 50-300 μmol/L) significantly promoted proliferation of hiPSC-MSCs. NaHS prevented the hypoxia-induced apoptosis and suppressed BKCa currents without altering the expression levels of α- and β-KCa 1.1. In addition, NaHS increased the phosphorylation of Akt and decreased the expression of Caspase 8 and Bax in hiPSC-MSCs. Paxilline (1 μmol/L), a BKCa blocker, showed similar effects on promoting cell proliferation and phosphorylation of Akt and suppression of apoptotic genes in hiPSC-MSCs.
  
  
  CONCLUSIONS
  Our data confirmed that H2S arguments the proliferation and survival of hiPSC-MSCs through activation of the PI3K-Akt pathway and that such effects could be mediated through inhibition of BKCa.
authors.affiliation: Research and Development Unit, National Heart Centre Singapore, Singapore, Republic of Singapore; Department of Clinical Pharmacy, China Pharmaceutical University, Nanjing, China.
authors.forename: Yongxing
authors.initials: Y
authors.lastname: Zhao
authors.forename: Heming
authors.initials: H
authors.lastname: Wei
authors.forename: Geraldine
authors.initials: G
authors.lastname: Kong
authors.forename: Winston
authors.initials: W
authors.lastname: Shim
authors.forename: Guangqin
authors.initials: G
authors.lastname: Zhang
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053181:Caspase 8 / Q000096:biosynthesis; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D064987:Cell- and Tissue-Based Therapy; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D057026:Induced Pluripotent Stem Cells / Q000187:drug effects*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
chemical_list: D007211:Indoles; D051036:Large-Conductance Calcium-Activated Potassium Channels; D026902:Potassium Channel Blockers; D051028:bcl-2-Associated X Protein; C048220:paxilline; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D053181:Caspase 8; D006862:Hydrogen Sulfide
keywords: PI3K/Akt pathway; apoptosis; human induced pluripotent stem cell–derived mesenchymal stromal cells; large-conductance calcium-activated K(+) channels; proliferation