title: Global remodeling of the vascular stem cell niche in bone marrow of diabetic patients: implication of the microRNA-155/FOXO3a signaling pathway.
abstract: BACKGROUND
  The impact of diabetes mellitus on bone marrow (BM) structure is incompletely understood.
  
  
  OBJECTIVE
  Investigate the effect of type-2 diabetes mellitus (T2DM) on BM microvascular and hematopoietic cell composition in patients without vascular complications.
  
  
  RESULTS
  Bone samples were obtained from T2DM patients and nondiabetic controls (C) during hip replacement surgery and from T2DM patients undergoing amputation for critical limb ischemia. BM composition was assessed by histomorphometry, immunostaining, and flow cytometry. Expressional studies were performed on CD34(pos) immunosorted BM progenitor cells (PCs). Diabetes mellitus causes a reduction of hematopoietic tissue, fat deposition, and microvascular rarefaction, especially when associated with critical limb ischemia. Immunohistochemistry documented increased apoptosis and reduced abundance of CD34(pos)-PCs in diabetic groups. Likewise, flow cytometry showed scarcity of BM PCs in T2DM and T2DM+critical limb ischemia compared with C, but similar levels of mature hematopoietic cells. Activation of apoptosis in CD34(pos)-PCs was associated with upregulation and nuclear localization of the proapoptotic factor FOXO3a and induction of FOXO3a targets, p21 and p27(kip1). Moreover, microRNA-155, which regulates cell survival through inhibition of FOXO3a, was downregulated in diabetic CD34(pos)-PCs and inversely correlated with FOXO3a levels. The effect of diabetes mellitus on anatomic and molecular end points was confirmed when considering background covariates. Furthermore, exposure of healthy CD34(pos)-PCs to high glucose reproduced the transcriptional changes induced by diabetes mellitus, with this effect being reversed by forced expression of microRNA-155.
  
  
  CONCLUSIONS
  We provide new anatomic and molecular evidence for the damaging effect of diabetes mellitus on human BM, comprising microvascular rarefaction and shortage of PCs attributable to activation of proapoptotic pathway.
authors.affiliation: Laboratories of Experimental Cardiovascular Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Gaia
authors.initials: G
authors.lastname: Spinetti
authors.forename: Daniela
authors.initials: D
authors.lastname: Cordella
authors.forename: Orazio
authors.initials: O
authors.lastname: Fortunato
authors.forename: Elena
authors.initials: E
authors.lastname: Sangalli
authors.forename: Sergio
authors.initials: S
authors.lastname: Losa
authors.forename: Ambra
authors.initials: A
authors.lastname: Gotti
authors.forename: Franco
authors.initials: F
authors.lastname: Carnelli
authors.forename: Francesco
authors.initials: F
authors.lastname: Rosa
authors.forename: Stefano
authors.initials: S
authors.lastname: Riboldi
authors.forename: Fausto
authors.initials: F
authors.lastname: Sessa
authors.forename: Elisa
authors.initials: E
authors.lastname: Avolio
authors.forename: Antonio Paolo
authors.initials: AP
authors.lastname: Beltrami
authors.forename: Constanza
authors.initials: C
authors.lastname: Emanueli
authors.forename: Paolo
authors.initials: P
authors.lastname: Madeddu
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001856:Bone Marrow Examination; D016022:Case-Control Studies; D019070:Cell Lineage; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D003925:Diabetic Angiopathies / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007511:Ischemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D055806:Microvessels / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D058729:Peripheral Arterial Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction; D055153:Stem Cell Niche; D014162:Transfection
chemical_list: D018952:Antigens, CD34; D015415:Biomarkers; C493956:CDKN1A protein, human; C436291:CDKN1B protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C524942:MIRN155 microRNA, human; D035683:MicroRNAs; D050760:Cyclin-Dependent Kinase Inhibitor p27