title: Differentiation status of human renal proximal and distal tubular epithelial cells in vitro: Differential expression of characteristic markers.
abstract: BACKGROUND
  The culture of human renal tubular cells of well-defined nephron origin is an important basis in the research of various physiological and pathophysiological mechanisms in the kidney. In vitro differentiation of cultured cells is affected by cell isolation and culture conditions. Our study describes in vitro differentiation of cultured human renal proximal and distal (thick ascending limb and early distal) tubular epithelial cells.
  
  
  METHODS
  Proximal tubular cells (PTC) and early distal tubular cells (DTC) were isolated immunomagnetically and cultured. In vitro differentiation was assessed by Western blot analysis and reverse transcriptase polymerase chain reaction using characteristic markers. Morphologic characterization was shown by fluorescence and scanning electron microscopy.
  
  
  RESULTS
  E-cadherin was highly expressed in DTC, whereas expression was low in PTC. In contrast to DTC, in PTC, intercellular adhesion molecule 1 and aquaporin 1 were constitutively expressed at high levels. Both cell types expressed cytokeratin 18 and Na-K-ATPase but not alpha-smooth muscle actin. Morphological analysis showed that PTC develop long microvilli, whereas DTC formed short microvilli in culture, and both express the tight junction protein zona occludens protein 1.
  
  
  CONCLUSIONS
  We demonstrate differential expression of E-cadherin, intercellular adhesion molecule 1 and aquaporin 1 in cultured PTC and DTC as described for the renal tubule in vivo. We could show the in vitro differentiation of the cells, and thus, their usefulness as an in vitro model of the human proximal and early distal tubule.
authors.affiliation: Division of Nephrology, Department of Internal Medicine III, J W Goethe University, Frankfurt/Main, Germany. P.Baer@em.uni-frankfurt.de
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Baer
authors.forename: Jurgen
authors.initials: J
authors.lastname: Bereiter-Hahn
authors.forename: Ralf
authors.initials: R
authors.lastname: Schubert
authors.forename: Helmut
authors.initials: H
authors.lastname: Geiger
mesh_terms: D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D051398:Aquaporin 1 / Q000378:metabolism; D051399:Aquaporin 2 / Q000235:genetics; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002469:Cell Separation; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D053538:Keratin-18 / Q000378:metabolism; D007686:Kidney Tubules, Distal / Q000166:cytology*; D007687:Kidney Tubules, Proximal / Q000166:cytology*; D008565:Membrane Proteins / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D009088:Mucoproteins / Q000235:genetics; D051762:PAX2 Transcription Factor / Q000235:genetics; D010750:Phosphoproteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D058949:Uromodulin; D062826:Zonula Occludens-1 Protein
chemical_list: C496020:AQP1 protein, human; C496023:AQP2 protein, human; D000943:Antigens, Differentiation; D051399:Aquaporin 2; D015820:Cadherins; D053538:Keratin-18; D008565:Membrane Proteins; D009088:Mucoproteins; D051762:PAX2 Transcription Factor; C497318:PAX2 protein, human; D010750:Phosphoproteins; C569042:TJP1 protein, human; C548612:UMOD protein, human; D058949:Uromodulin; D062826:Zonula Occludens-1 Protein; D018799:Intercellular Adhesion Molecule-1; D051398:Aquaporin 1; D000254:Sodium-Potassium-Exchanging ATPase