title: Detection of circulating endothelial cells via a microfluidic disk.
abstract: BACKGROUND
  Circulating endothelial cells (CECs) in the blood are rare but have been shown to be associated with various diseases. With the ratio of CECs to peripheral blood mononuclear cells (PBMCs) less than 1 part per thousand, their separation from PBMCs and detection are challenging. We present a means of detecting CECs from PBMCs via an economical microfluidic disk with a model cell system [human umbilical vein endothelial cells (HUVECs) in PBMCs], along with demonstration of its efficacy clinically.
  
  
  METHODS
  To enrich these rare cells, we used immunomagnetic beads and a tailor-made magnet on the disk. CEC-simulating HUVECs, as target cells, were stained with primary anti-CD146-phycoerythrin antibody and bound with secondary antibody on antiphycoerythrin magnetic beads. PBMCs served as nontarget cells and were labeled with anti-CD45-FITC antibody.
  
  
  RESULTS
  When hundreds of HUVECs were mixed in 10(6) PBMCs, 95% of spiked HUVECs were detected. This yield also held for 60 HUVEC in <10(4) PBMCs. We compared data from flow cytometry with that from the disk: CEC counts in 50 μL blood from patients with systemic lupus erythematosus were 61.1 (21.5), significantly higher (P < 0.01) than those of healthy donors, 31.2 (13.3).
  
  
  CONCLUSIONS
  The count of CECs is a suitable marker for symptoms of systemic lupus erythematosus. The microfluidic disk system should be a viable platform for detection of CECs.
authors.affiliation: Institute of Applied Mechanics, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Ken-Chao
authors.initials: KC
authors.lastname: Chen
authors.forename: Tai-Ping
authors.initials: TP
authors.lastname: Lee
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Pan
authors.forename: Chi-Ling
authors.initials: CL
authors.lastname: Chiang
authors.forename: Chen-Lin
authors.initials: CL
authors.lastname: Chen
authors.forename: Yao-Hsu
authors.initials: YH
authors.lastname: Yang
authors.forename: Bor-Luen
authors.initials: BL
authors.lastname: Chiang
authors.forename: Hsinyu
authors.initials: H
authors.lastname: Lee
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Wo
mesh_terms: D004730:Endothelium, Vascular / Q000166:cytology*; D005434:Flow Cytometry; D006801:Humans; D044085:Microfluidics / Q000295:instrumentation*