title: Nitric oxide depletion alters hematopoietic stem cell commitment toward immunogenic dendritic cells.
abstract: BACKGROUND
  NO* is a key molecule involved in the regulation of cell survival, proliferation and differentiation in many cell types. In this study we investigated the contribution of NO* during the differentiation of human peripheral blood hemopoietic stem cells (CD34+HSCs) toward immunogenic dendritic cells (i-DCs).
  
  
  METHODS
  We depleted autocrine NO* production, using NG-monomethyl-L-arginine monoacetate (L-NMMA) and paracrine NO', using oxy-hemoglobin (HbO2) as a NO* scavenger during in vitro differentiation of CD34+HSCs to i-DCs. We monitored the NO* level, cell proliferation, phenotype and differentiation potential.
  
  
  RESULTS
  We found that the depletion of paracrine or autocrine NO* correlated with (I) an active proliferation state at the end of differentiation, when control cells were not proliferating; (II) a significant reduction in the expression levels of differentiative markers (CD1a and HLA-DR) with a parallel high expression of the CD34 marker (III) with a retrieved clonogenic ability compared to control cells.
  
  
  CONCLUSIONS
  On the whole, our data indicate that the depletion of NO* during the commitment stage blocks CD34+HSC differentiation into i-DCs and maintains an undifferentiated, highly proliferating cell population, indicating/revealing a novel role for NO* in the commitment of CD34+HSCs into i-DCs.
  
  
  CONCLUSIONS
  The essential finding of the present study is that NO*, produced in HSCs by NOS enzymes, may act as autocrine and paracrine effectors regulating the in vitro differentiation process of CD34+-HSCs toward i-DCs.
authors.affiliation: Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Sezione di Biochimica e Biologia Molecolare, Università di Perugia, Via del Giochetto, 06100 Perugia, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tiribuzi
authors.forename: Lucia
authors.initials: L
authors.lastname: Crispoltoni
authors.forename: Francesco
authors.initials: F
authors.lastname: Tartacca
authors.forename: Antonio
authors.initials: A
authors.lastname: Orlacchio
authors.forename: Sabata
authors.initials: S
authors.lastname: Martino
authors.forename: Carlo Alberto
authors.initials: CA
authors.lastname: Palmerini
authors.forename: Aldo
authors.initials: A
authors.lastname: Orlacchio
mesh_terms: D018949:Antigens, CD1 / Q000235:genetics / Q000276:immunology; D018952:Antigens, CD34 / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D016130:Immunophenotyping; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D018949:Antigens, CD1; D018952:Antigens, CD34; C419393:CD1a antigen; D004791:Enzyme Inhibitors; D006684:HLA-DR Antigens; D010108:Oxyhemoglobins; D019323:omega-N-Methylarginine; D009569:Nitric Oxide