title: Reduced circulating endothelial progenitor cells in reversible cerebral vasoconstriction syndrome.
abstract: BACKGROUND
  The pathophysiology of reversible cerebral vasoconstriction syndrome (RCVS) remains elusive. Endothelial dysfunction might play a role, but direct evidence is lacking. This study aimed to explore whether patients with RCVS have a reduced level of circulating circulating endothelial progenitor cells (EPCs) to repair the dysfunctional endothelial vasomotor control.
  
  
  METHODS
  We prospectively recruited 24 patients with RCVS within one month of disease onset and 24 healthy age- and sex-matched controls. Flow cytometry was used to quantify the numbers of circulating EPCs, defined as KDR+CD133+, CD34+CD133+, and CD34+KDR+ double-positive mononuclear cells. The Lindegaard index, an index of vasoconstriction, was calculated by measuring the mean flow velocity of middle cerebral arteries and distal extracranial internal carotid arteries via color-coded sonography on the same day as blood drawing. A Lindegaard index of 2 was chosen as the cutoff value for significant vasoconstriction of middle cerebral arteries based on our previous study.
  
  
  RESULTS
  Patients with RCVS had a reduced number of CD34+KDR+ cells (0.009 ± 0.006% vs. 0.014 ± 0.010%, p = 0.031) but not KDR+CD133+ cells or CD34+CD133+ EPCs, in comparison with controls. The number of CD34+KDR+ cells was inversely correlated with the Lindegaard index (rs = -0.418, p = 0.047). Of note, compared to controls, patients with a Lindegaard index > 2 (n = 13) had a reduced number of CD34+KDR+ cells (0.007 ± 0.005% vs. 0.014 ± 0.010%, p = 0.010), but those with a Lindegaard index ≤ 2 did not.
  
  
  CONCLUSIONS
  Patients with RCVS had reduced circulating CD34+KDR+ EPCs, which were correlated with the severity of vasoconstriction. Endothelial dysfunction might contribute to the pathogenesis of RCVS.
authors.forename: Shih-Pin
authors.initials: SP
authors.lastname: Chen
authors.forename: Yen-Feng
authors.initials: YF
authors.lastname: Wang
authors.forename: Po-Hsun
authors.initials: PH
authors.lastname: Huang
authors.forename: Chin-Wen
authors.initials: CW
authors.lastname: Chi
authors.affiliation: Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. jlfuh@vghtpe.gov.tw.
authors.forename: Jong-Ling
authors.initials: JL
authors.lastname: Fuh
authors.forename: Shuu-Jiun
authors.initials: SJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D066026:Endothelial Progenitor Cells / Q000166:cytology*; D005260:Female; D005434:Flow Cytometry; D051270:Headache Disorders, Primary / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014661:Vasoconstriction / Q000502:physiology*; D020301:Vasospasm, Intracranial / Q000097:blood*