title: In vitro analysis of human periodontal microvascular endothelial cells.
abstract: BACKGROUND
  Endothelial cells (ECs) participate in key aspects of vascular biology, such as maintenance of capillary permeability, initiation of coagulation, and regulation of inflammation. According to previous reports, ECs have revealed highly specific characteristics depending on the organs and tissues. However, some reports have described the characteristics of the capillaries formed by human periodontal ECs. Therefore, the aim of the present study is to examine the functional characteristics of the periodontal microvascular ECs in vitro.
  
  
  METHODS
  Human periodontal ligament-endothelial cells (HPDL-ECs) and human gingiva-endothelial cells (HG-ECs) were isolated by immunoprecipitation with magnetic beads conjugated to a monoclonal anti-CD31 antibody. The isolated HPDL-ECs and HG-ECs were characterized to definitively demonstrate that these cell cultures represented pure ECs. Human umbilical-vein ECs and human dermal microvascular ECs were used for comparison. These cells were compared according to the proliferation potential, the formation of capillary-like tubes, the transendothelial electric resistance (TEER), and the expression of tight junction proteins.
  
  
  RESULTS
  HPDL-ECs and HG-ECs with characteristic cobblestone monolayer morphology were obtained, as determined by light microscopy at confluence. Furthermore, the HPDL-ECs and HG-ECs expressed the EC markers platelet endothelial cell adhesion molecule-1 (also known as CD31), von Willebrand factor, and Ulex europaeus agglutinin 1, and the cells stained strongly positive for CD31 and CD309. In addition, the HPDL-ECs and HG-ECs were observed to form capillary-like tubes, and they demonstrated uptake of acetylated low-density lipoprotein. Functional analyses of the HPDL-ECs and HG-ECs showed that, compared to the control cells, tube formation persisted for only a brief period of time, and TEER was substantially reduced at confluence. Furthermore, the cells exhibited delocalization of zonula occludens-1 and occludin at cell-cell contact sites.
  
  
  CONCLUSIONS
  The present results provide new evidence that HPDL-ECs and HG-ECs have characteristics of fenestrated capillaries. Therefore, capillaries in human periodontal tissues have functional characteristics of fenestrated capillaries, which might be related to the onset and the progression of systemic diseases and inflammation.
authors.affiliation: Department of Periodontology, The Nippon Dental University, School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Tsubokawa
authors.forename: Soh
authors.initials: S
authors.lastname: Sato
mesh_terms: D000293:Adolescent; D000328:Adult; D002196:Capillaries / Q000166:cytology; D018929:Cell Culture Techniques; D049109:Cell Proliferation; D002469:Cell Separation; D048430:Cell Shape; D002478:Cells, Cultured; D017097:Electric Impedance; D042783:Endothelial Cells / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology*; D005260:Female; D005881:Gingiva / Q000098:blood supply / Q000166:cytology; D061307:Human Umbilical Vein Endothelial Cells / Q000502:physiology; D006801:Humans; D008077:Lipoproteins, LDL / Q000032:analysis; D008297:Male; D010513:Periodontal Ligament / Q000098:blood supply* / Q000166:cytology; D037121:Plant Lectins / Q000032:analysis; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D012867:Skin / Q000098:blood supply / Q000166:cytology; D062725:Tight Junction Proteins / Q000032:analysis; D039762:Ulex; D055815:Young Adult; D062826:Zonula Occludens-1 Protein / Q000032:analysis; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D008077:Lipoproteins, LDL; D037121:Plant Lectins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D062725:Tight Junction Proteins; C036850:Ulex europaeus lectins; D062826:Zonula Occludens-1 Protein; D014841:von Willebrand Factor
keywords: Capillaries; electrical impedance; endothelial cells; periodontium; tight junctions