title: Pericytes augment the capillary barrier in in vitro cocultures.
abstract: Most in vitro studies of capillary permeability focus on endothelial cell (MVEC) monolayers and ignore the second cell that forms the capillary wall: the microvascular pericyte (PC). We describe a model to study the permeability characteristics of MVEC, PC, and MVEC:PC cocultures.
  
  
  METHODS
  Semipermeable culture inserts were coated with collagen and then plated with early passage bovine pulmonary MVEC. On Day 3, bovine pulmonary PC were added at concentrations to approximate MVEC:PC ratios of 1:1, 5:1, and 10:1. Electrical resistance was measured on subsequent days and fluorescently labeled (FITC) albumin was used in a permeability assay to calculate an albumin clearance for each culture.
  
  
  RESULTS
  The results for electrical resistance measurements and albumin assays showed a similar pattern. Resistance for endothelial cell monolayers was significantly higher and albumin permeability was significantly lower than that of controls. Addition of pericytes at a 10:1 and 5:1 ratios increased the permeability barrier compared to endothelial cells alone, although these cultures were not significantly different from one another. Cocultures at a 1:1 ratio had the best barrier, significantly better than all other cultures.
  
  
  CONCLUSIONS
  Endothelial cell monolayers are an inadequate model of the microcirculation. As PC form a key component of the capillary wall in vivo and as addition of PC to MVEC monolayers in vitro, optimally at a 1:1 ratio, increase their barrier effect to large and small molecules, we believe it is necessary to include both cells in future in vitro studies.
authors.affiliation: Department of Surgery, Wayne State University, Detroit, Michigan 48201, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Dente
authors.forename: C P
authors.initials: CP
authors.lastname: Steffes
authors.forename: C
authors.initials: C
authors.lastname: Speyer
authors.forename: J G
authors.initials: JG
authors.lastname: Tyburski
mesh_terms: D000418:Albumins / Q000378:metabolism; D000818:Animals; D002199:Capillary Permeability; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division; D002478:Cells, Cultured; D017097:Electric Impedance; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D007700:Kinetics; D020286:Pericytes / Q000502:physiology*
chemical_list: D000418:Albumins