title: Direct measurement of local oxygen concentration in the bone marrow of live animals.
abstract: Characterization of how the microenvironment, or niche, regulates stem cell activity is central to understanding stem cell biology and to developing strategies for the therapeutic manipulation of stem cells. Low oxygen tension (hypoxia) is commonly thought to be a shared niche characteristic in maintaining quiescence in multiple stem cell types. However, support for the existence of a hypoxic niche has largely come from indirect evidence such as proteomic analysis, expression of hypoxia inducible factor-1α (Hif-1α) and related genes, and staining with surrogate hypoxic markers (for example, pimonidazole). Here we perform direct in vivo measurements of local oxygen tension (pO2) in the bone marrow of live mice. Using two-photon phosphorescence lifetime microscopy, we determined the absolute pO2 of the bone marrow to be quite low (<32 mm Hg) despite very high vascular density. We further uncovered heterogeneities in local pO2, with the lowest pO2 (∼9.9 mm Hg, or 1.3%) found in deeper peri-sinusoidal regions. The endosteal region, by contrast, is less hypoxic as it is perfused with small arteries that are often positive for the marker nestin. These pO2 values change markedly after radiation and chemotherapy, pointing to the role of stress in altering the stem cell metabolic microenvironment.
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [3] Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA.
authors.forename: Joel A
authors.initials: JA
authors.lastname: Spencer
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Ferraro
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Roussakis
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Alyssa
authors.initials: A
authors.lastname: Klein
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Juwell
authors.initials: J
authors.lastname: Wu
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Judith M
authors.initials: JM
authors.lastname: Runnels
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [3] Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University, Riyadh 11461, Saudi Arabia.
authors.forename: Walid
authors.initials: W
authors.lastname: Zaher
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Mortensen
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Clemens
authors.initials: C
authors.lastname: Alt
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [3] Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Turcotte
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Rushdia
authors.initials: R
authors.lastname: Yusuf
authors.affiliation: Département de Physique, Génie Physique et Optique and Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Université Laval, Québec City, Québec G1J 2G3, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Côté
authors.affiliation: Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Vinogradov
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Scadden
authors.affiliation: 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [2] Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA [3] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.
authors.forename: Charles P
authors.initials: CP
authors.lastname: Lin
mesh_terms: D000818:Animals; D001158:Arteries / Q000378:metabolism; D001853:Bone Marrow / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D002066:Busulfan / Q000494:pharmacology; D015687:Cell Hypoxia; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism; D000860:Hypoxia / Q000175:diagnosis / Q000378:metabolism; D008163:Luminescent Measurements; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008853:Microscopy; D064231:Nestin / Q000378:metabolism; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism; D017785:Photons; D055153:Stem Cell Niche / Q000187:drug effects / Q000528:radiation effects
chemical_list: D064231:Nestin; D002066:Busulfan; D010100:Oxygen