title: Ex vivo acidic preconditioning enhances bone marrow ckit+ cell therapeutic potential via increased CXCR4 expression.
abstract: OBJECTIVE
  The chemokine receptor CXCR4 modulates endothelial progenitor cell migration, homing, and differentiation, and plays a key role in cardiovascular regeneration. Here we examined the effect of ex vivo acidic preconditioning (AP) on CXCR4 expression and on the regenerative potential of mouse bone marrow (BM) ckit(+) cells.
  
  
  RESULTS
  Acidic preconditioning was achieved by exposing BM ckit(+) cells to hypercarbic acidosis (pH 7.0) for 24 h; control cells were kept at pH 7.4. Acidic preconditioning enhanced CXCR4 and stromal cell-derived factor 1 (SDF-1) mRNA levels, as well as CXCR4 phosphorylation. Acidic preconditioning ability to modulate CXCR4 expression depended on cytosolic calcium [Ca(2+)]i mobilization and on nitric oxide (NO), as determined by [Ca(2+)]i buffering with BAPTA, and by treatment with the NO donor (DETA/NO) and the NO synthase inhibitor (L-NAME). Further, AP increased SDF-1-driven chemotaxis, transendothelial migration, and differentiation toward the endothelial lineage in vitro. In a mouse model of hindlimb ischaemia, control and AP ckit(+) cells were transplanted into the ischaemic muscle; AP cells accelerated blood flow recovery, increased capillary, and arteriole number as well as the number of regenerating muscle fibres vs. control. These effects were abolished by treating AP cells with L-NAME.
  
  
  CONCLUSIONS
  Acidic preconditioning represents a novel strategy to enhance BM ckit(+) cell therapeutic potential via NO-dependent increase in CXCR4 expression.
authors.affiliation: Laboratorio di Biologia vascolare e Medicina Rigenerativa, Centro Cardiologico Monzino-IRCCS, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Cencioni
authors.forename: Roberta
authors.initials: R
authors.lastname: Melchionna
authors.forename: Stefania
authors.initials: S
authors.lastname: Straino
authors.forename: Marta
authors.initials: M
authors.lastname: Romani
authors.forename: Claudia
authors.initials: C
authors.lastname: Cappuzzello
authors.forename: Valentina
authors.initials: V
authors.lastname: Annese
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Wu
authors.forename: Giulio
authors.initials: G
authors.lastname: Pompilio
authors.forename: Angela
authors.initials: A
authors.lastname: Santoni
authors.forename: Carlo
authors.initials: C
authors.lastname: Gaetano
authors.forename: Monica
authors.initials: M
authors.lastname: Napolitano
authors.forename: Maurizio C
authors.initials: MC
authors.lastname: Capogrossi
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology*; D016026:Bone Marrow Transplantation / Q000379:methods*; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002614:Chelating Agents / Q000494:pharmacology; D054377:Chemokine CXCL12 / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply; D006863:Hydrogen-Ion Concentration; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007511:Ischemia / Q000517:prevention & control; D019194:Ischemic Preconditioning / Q000379:methods; D008297:Male; D051379:Mice; D020030:Nitric Oxide Donors / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D019718:Receptors, CXCR4 / Q000378:metabolism*; D012038:Regeneration / Q000502:physiology*
chemical_list: D002614:Chelating Agents; D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020030:Nitric Oxide Donors; D019718:Receptors, CXCR4; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D019009:Proto-Oncogene Proteins c-kit