title: Altered profile of circulating endothelial progenitor cells in obstructive sleep apnea.
abstract: BACKGROUND
  Obstructive sleep apnea (OSA) is independently associated with endothelial dysfunction, which may be perpetuated by alteration in endothelial repair capacity. Our study evaluates changes in endothelial progenitor cell (EPC) profile in relation to OSA and the role of advanced glycation end-products (AGE) in this relationship.
  
  
  METHODS
  Consecutive Chinese adults undergoing sleep studies, who had no medical illnesses or regular medications, were enrolled. Subjects with morbid obesity or grossly elevated lipoprotein levels were excluded from analysis. Circulating EPC was measured with flow cytometry analysis.
  
  
  RESULTS
  Seventy-two subjects, 64 % with OSA defined by apnea-hypopnea index (AHI) ≥ 5, were analyzed. CD34+ cell counts were positively correlated with oxygen desaturation index (ODI) (r = 0.250, p = 0.041) and duration of oxygen desaturation <90 % (T90) (r = 0.261, p = 0.033) and negatively with minimal oxygen saturation (r = -0.247, p = 0.044) after adjusting for age, glucose, body weight, and smoking status. AGE was positively correlated with indices of OSA severity (AHI, r = 0.249, p = 0.042; ODI, r = 0.244, p = 0.047; T90, r = 0.243, p = 0.047; minimal oxygen saturation, r = -0.251, p = 0.041) and negatively with CD133+ cells (r = -0.281, p = 0.021). On stepwise multiple linear regression analysis, minimal oxygen saturation (p = 0.013) and CD133+ cell counts (p = 0.029) were found to be significant determinants of AGE level (R(2) = 0.147).
  
  
  CONCLUSIONS
  Nocturnal hypoxemia in OSA subjects was associated with increase in endothelial cells (CD34+) which may promote vascular repair. Accumulation of AGE in OSA may lead to diminution in early EPC (CD133+) and endothelial repair capacity over time, thus contributing to vascular pathogenesis.
authors.affiliation: Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Macy Mei-Sze
authors.initials: MM
authors.lastname: Lui
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.forename: Judith Choi-Wo
authors.initials: JC
authors.lastname: Mak
authors.forename: Jamie Chung-Mei
authors.initials: JC
authors.lastname: Lam
authors.forename: David Chi-Leung
authors.initials: DC
authors.lastname: Lam
authors.forename: Kathryn C B
authors.initials: KC
authors.lastname: Tan
authors.forename: Mary Sau-Man
authors.initials: MS
authors.lastname: Ip
mesh_terms: D000071916:AC133 Antigen; D000328:Adult; D015703:Antigens, CD / Q000097:blood; D018952:Antigens, CD34 / Q000097:blood; D002452:Cell Count; D002940:Circadian Rhythm / Q000502:physiology; D042783:Endothelial Cells / Q000502:physiology*; D005260:Female; D017127:Glycation End Products, Advanced / Q000097:blood; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010455:Peptides / Q000097:blood; D017286:Polysomnography; D012016:Reference Values; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D013234:Stem Cells / Q000502:physiology*
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D018952:Antigens, CD34; D017127:Glycation End Products, Advanced; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D010100:Oxygen