BackgroundGlioblastoma　(GBM)　is　the　most　common　type　of　primary　malignant　brain　tumor.　Molecular　hydrogen　has　been　considered　a　preventive　and　therapeutic　medical　gas　in　many　diseases　including　cancer.　In　our　study,　we　sought　to　assess　the　potential　role　of　molecular　hydrogen　on　GBM.MethodsThe　in　vivo　studies　were　performed　using　a　rat　orthotopic　glioma　model　and　a　mouse　subcutaneous　xenograft　model.　Animals　inhaled　hydrogen　gas　(67%)　1h　two　times　per　day.　MR　imaging　studies　were　performed　to　determine　the　tumor　volume.　Immunohistochemistry　(IHC),　immunofluorescence　staining,　and　flow　cytometry　analysis　were　conducted　to　determine　the　expression　of　surface　markers.　Sphere　formation　assay　was　performed　to　assess　the　cancer　stem　cell　self-renewal　capacity.　Assays　for　cell　migration,　invasion,　and　colony　formation　were　conducted.ResultsThe　in　vivo　study　showed　that　hydrogen　inhalation　could　effectively　suppress　GBM　tumor　growth　and　prolong　the　survival　of　mice　with　GBM.　IHC　and　immunofluorescence　staining　demonstrated　that　hydrogen　treatment　markedly　downregulated　the　expression　of　markers　involved　in　stemness　(CD133,　Nestin),　proliferation　(ki67),　and　angiogenesis　(CD34)　and　also　upregulated　GFAP　expression,　a　marker　of　differentiation.　Similar　results　were　obtained　in　the　in　vitro　studies.　The　sphere-forming　ability　of　glioma　cells　was　also　suppressed　by　hydrogen　treatment.　Moreover,　hydrogen　treatment　also　suppressed　the　migration,　invasion,　and　colony-forming　ability　of　glioma　cells.ConclusionsTogether,　these　results　indicated　that　molecular　hydrogen　may　serve　as　a　potential　anti-tumor　agent　in　the　treatment　of　GBM.