Pharmaceutical Research

, Volume 23, Issue 7, pp 1491–1501 | Cite as

A Novel Tool to Characterize Paracellular Transport: The APTS–Dextran Ladder

  • Winfried Neuhaus
  • Elisabeth Bogner
  • Michael Wirth
  • Joanna Trzeciak
  • Bodo Lachmann
  • Franz Gabor
  • Christian R. Noe
Research Paper


The aim of this work was to develop an easy, manageable, and precise analytic tool to describe the tightness of cell layers by a molecular weight ladder.


Dextrans were labeled by reductive amination with fluorescent 8-aminopyrene-1,3,6-trisulfonate (APTS). This mixture, including the internal standard diazepam, was used for transport studies in Transwell models using Caco-2, ECV304, and PBMEC/C1–2 cell lines. Samples were analyzed by fluorimetry, capillary electrophoresis, and reverse-phase high-performance liquid chromatography.


Following this approach, a logarithm correlation of R 2 = 0.8958 between transepithelial electrical resistance (TEER) and APTS–dextran permeability was shown. In addition, a TEER-dependent permeability pattern could be observed including each single fraction from free APTS, APTS–glucose up to APTS–dextran consisting of 35 glucose units. The TEER-independent permeability coefficients of diazepam and confocal laser scanning microscopy images confirmed the paracellular transport of APTS–dextran.


All in all, the developed APTS–dextran ladder is a useful tool to characterize cell layer tightness and especially to describe paracellular transport ways and the extent of leakiness of cell layers (for blood–brain barrier or intestinal studies) over time—applying a wide array from smaller to larger molecules at the same time to refine TEER, sucrose, or Evans blue measurements.

Key words

APTS–dextran BBB blood–brain barrier cell layer tightness paracellular transport 



astrocyte conditioned medium




blood–brain barrier


brain microvascular endothelial cells


confocal laser scanning microscopy


FITC dextran


fluorescein isothiocyanate

LIF detector

laser-induced fluorescence detector




transendothelial electrical resistance for studies with cell lines ECV304 and PBMEC/C1–2, transepithelial electrical resistance in case of Caco-2


von Willebrand factor





We gratefully acknowledge the financial support provided by the Austrian Science Fund FWF (project P–14582 CHE).


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Copyright information

© Springer Science + Business Media, Inc. 2006

Authors and Affiliations

  • Winfried Neuhaus
    • 1
  • Elisabeth Bogner
    • 2
  • Michael Wirth
    • 2
  • Joanna Trzeciak
    • 1
  • Bodo Lachmann
    • 1
  • Franz Gabor
    • 2
  • Christian R. Noe
    • 1
  1. 1.Department of Medicinal ChemistryUniversity of Vienna, Pharmacy CenterViennaAustria
  2. 2.Department of Pharmaceutical Technology and BiopharmaceuticsUniversity of Vienna, Pharmacy CenterViennaAustria

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