title: Nocturnal stem cell mobilization in patients with obstructive sleep apnoea: a pilot study.
abstract: BACKGROUND
  Patients with obstructive sleep apnoea (OSA) experience repetitive cessation of breathing during sleep, leading to intermittent hypoxaemia, excessive oxidative stress and systemic inflammation. These insults may damage the vasculature and provoke the corresponding repair response, such as stem cell mobilization to peripheral blood. This study aimed to investigate nocturnal mobilization of stem cells in OSA.
  
  
  METHODS
  Thirty-five patients with OSA and thirteen healthy controls were enrolled. Polysomnography was performed, and severity of OSA was defined by apnoea-hypopnoea index (AHI). Peripheral venous blood was drawn after and before sleep for measurement of CD34+ cell and SDF-1α level. Stem cell mobilization was gauged by ratios of the CD34+ level in the morning to that at night or by their difference. Correlation analysis was performed to identify factors related to stem cell mobilization.
  
  
  RESULTS
  Compared to controls, the nocturnal ratios and difference of CD34+ cell levels were larger in patients with OSA (ratios: 1·141 vs. 0·896, P = 0·036; difference: 340 vs. -166/cc blood, P = 0·036), suggestive of stem cell mobilization. The mobilization ratios were related to AHI, body mass index (BMI), SpO2 nadir, oxygen desaturation index and time sustaining hypoxaemia. After adjusting age, gender and BMI, AHI (r = 0·357, P = 0·016) and hypoxaemia-related parameter remained significant. Paired nocturnal differences in CD34+ cell count (P = 0·009) and SDF-1α (P = 0·001) were also significant in patients with OSA, but not in controls. After CPAP therapy for 6 months, the elevated mobilization ratios in patients with OSA tended to decline (P = 0·059).
  
  
  CONCLUSIONS
  CD34+ stem cell mobilization during sleep was observed in OSA.
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Kun-Ta
authors.initials: KT
authors.lastname: Chou
authors.forename: Chen-Chi
authors.initials: CC
authors.lastname: Liu
authors.forename: Han-Shui
authors.initials: HS
authors.lastname: Hsu
authors.forename: Shi-Chuan
authors.initials: SC
authors.lastname: Chang
authors.forename: Yuh-Min
authors.initials: YM
authors.lastname: Chen
authors.forename: Diahn-Warng
authors.initials: DW
authors.lastname: Perng
authors.forename: Yuan-Tong
authors.initials: YT
authors.lastname: Hsu
authors.forename: Yu-Chin
authors.initials: YC
authors.lastname: Lee
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Hung
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002940:Circadian Rhythm; D045422:Continuous Positive Airway Pressure / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology; D010865:Pilot Projects; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D013234:Stem Cells / Q000502:physiology*
keywords: intermittent hypoxaemia; obstructive sleep apnoea; sleep-disordered breathing; stem cell mobilization