title: The relationship between endothelial progenitor cell populations and epicardial and microvascular coronary disease-a cellular, angiographic and physiologic study.
abstract: BACKGROUND
  Endothelial progenitor cells (EPCs) are implicated in protection against vascular disease. However, studies using angiography alone have reported conflicting results when relating EPCs to epicardial coronary artery disease (CAD) severity. Moreover, the relationship between different EPC types and the coronary microcirculation is unknown. We therefore investigated the relationship between EPC populations and coronary epicardial and microvascular disease.
  
  
  METHODS
  Thirty-three patients with a spectrum of isolated left anterior descending artery disease were studied. The coronary epicardial and microcirculation were physiologically interrogated by measurement of fractional flow reserve (FFR), index of microvascular resistance (IMR) and coronary flow reserve (CFR). Two distinct EPC populations (early EPC and late outgrowth endothelial cells [OECs]) were isolated from these patients and studied ex vivo.
  
  
  RESULTS
  There was a significant inverse relationship between circulating OEC levels and epicardial CAD severity, as assessed by FFR and angiography (r=0.371, p=0.04; r=-0.358, p=0.04; respectively). More severe epicardial CAD was associated with impaired OEC migration and tubulogenesis (r=0.59, p=0.005; r=0.589, p=0.004; respectively). Patients with significant epicardial CAD (FFR<0.75) had lower OEC levels and function compared to those without hemodynamically significant stenoses (p<0.05). In contrast, no such relationship was seen for early EPC number and function, nor was there a relationship between IMR and EPCs. There was a significant relationship between CFR and OEC function.
  
  
  CONCLUSIONS
  EPC populations differ in regards to their associations with CAD severity. The number and function of OECs, but not early EPCs, correlated significantly with epicardial CAD severity. There was no relationship between EPCs and severity of coronary microvascular disease.
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; The Heart Research Institute, Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Kim H
authors.initials: KH
authors.lastname: Chan
authors.affiliation: The Heart Research Institute, Sydney, New South Wales, Australia.
authors.forename: Philippa J L
authors.initials: PJ
authors.lastname: Simpson
authors.affiliation: Department of Cardiology, Concord Hospital, Sydney, New South Wales, Australia.
authors.forename: Andy S
authors.initials: AS
authors.lastname: Yong
authors.affiliation: The Heart Research Institute, Sydney, New South Wales, Australia.
authors.forename: Louise L
authors.initials: LL
authors.lastname: Dunn
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.
authors.forename: Chirapan
authors.initials: C
authors.lastname: Chawantanpipat
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; The Heart Research Institute, Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Chijen
authors.initials: C
authors.lastname: Hsu
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; The Heart Research Institute, Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Young
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia; National Health and Medical Research Council Clinical Trials Centre, Sydney, New South Wales, Australia.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Keech
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; The Heart Research Institute, Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: David S
authors.initials: DS
authors.lastname: Celermajer
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia; The Heart Research Institute, Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Martin K C
authors.initials: MK
authors.lastname: Ng
mesh_terms: D000368:Aged; D002452:Cell Count; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology; D003326:Coronary Circulation; D003327:Coronary Disease / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology*; D042783:Endothelial Cells / Q000378:metabolism; D066026:Endothelial Progenitor Cells / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D010496:Pericardium / Q000378:metabolism*; D011446:Prospective Studies; D012720:Severity of Illness Index
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