title: Absolute circulating pericyte progenitor cell counts in mice by flow cytometry: comparison of 2 single-platform technologies.
abstract: BACKGROUND
  Accumulating evidence indicates that circulating pericyte progenitor cells (CPPCs) may be angiogenic biomarkers in cancer and diabetes. Their validity as biomarkers depends on the accuracy of techniques used for enumeration. In this report, absolute CPPC counts were performed by 2 single-platform technologies. The reliability of the 2 methods, including retest reliability and intraobserver and interobserver variability, was assessed according to the intraclass correlation coefficient (ICC). The linear correlation and agreement among both methods were assessed, and the stability of CPPC numbers in blood samples was analyzed.
  
  
  METHODS
  The blood samples were obtained from ICR mice. The samples were processed through a no-lyse, 1-wash procedure, and Syto16+CD45-CD31-CD140b+ CPPCs were analyzed by exclusion of dead cells and by fluorescence-minus-one control. CPPCs were enumerated by 2 methods: bead-based 123count eBeads count (eBioscience) and direct volume-based Accuri C6 Flow Cytometer count (BD). The cells were measured immediately and after storage of blood samples for 24 and 48 hours.
  
  
  RESULTS
  There were excellent retest correlations and intraobserver and interobserver agreement in both methods. The 2 methods showed a high linear correlation (R2 = 0.923) and with a high level of agreement (0.986). It was demonstrated that CPPCs are unstable in blood samples.
  
  
  CONCLUSIONS
  In this study, 2 reproducible protocols for CPPC quantification were established. These protocols should facilitate future studies to further define the role of CPPCs as cellular biomarkers.
authors.affiliation: Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing - PR China.|Key Laboratory of Microcirculation, Ministry of Health, Beijing - PR China.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Yuan
authors.affiliation: Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing - PR China.|Key Laboratory of Microcirculation, Ministry of Health, Beijing - PR China.
authors.forename: Qingbin
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing - PR China.|Key Laboratory of Microcirculation, Ministry of Health, Beijing - PR China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing - PR China.|Key Laboratory of Microcirculation, Ministry of Health, Beijing - PR China.
authors.forename: Bingwei
authors.initials: B
authors.lastname: Li
authors.affiliation: Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing - PR China.|Key Laboratory of Microcirculation, Ministry of Health, Beijing - PR China.
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Xiu
mesh_terms: D000818:Animals; D002452:Cell Count; D002469:Cell Separation; D005434:Flow Cytometry; D008297:Male; D008813:Mice, Inbred ICR; D020286:Pericytes / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*