Measurement of the airway surface liquid volume with simple light refraction microscopy

Am J Respir Cell Mol Biol. 2011 Sep;45(3):592-9. doi: 10.1165/rcmb.2010-0484OC. Epub 2011 Jan 14.


In the cystic fibrosis (CF) lung, the airway surface liquid (ASL) volume is depleted, impairing mucus clearance from the lung and leading to chronic airway infection and obstruction. Several therapeutics have been developed that aim to restore normal airway surface hydration to the CF airway, yet preclinical evaluation of these agents is hindered by the paucity of methods available to directly measure the ASL. Therefore, we sought to develop a straightforward approach to measure the ASL volume that would serve as the basis for a standardized method to assess mucosal hydration using readily available resources. Primary human bronchial epithelial (HBE) cells cultured at an air-liquid interface develop a liquid meniscus at the edge of the culture. We hypothesized that the size of the fluid meniscus is determined by the ASL volume, and could be measured as an index of the epithelial surface hydration status. A simple method was developed to measure the volume of fluid present in meniscus by imaging the refraction of light at the ASL interface with the culture wall using low-magnification microscopy. Using this method, we found that primary CF HBE cells had a reduced ASL volume compared with non-CF HBE cells, and that known modulators of ASL volume caused the predicted responses. Thus, we have demonstrated that this method can detect physiologically relevant changes in the ASL volume, and propose that this novel approach may be used to rapidly assess the effects of airway hydration therapies in high-throughput screening assays.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bronchi / cytology*
  • Cell Line
  • Cystic Fibrosis / pathology*
  • Cystic Fibrosis Transmembrane Conductance Regulator / genetics
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • Epithelial Sodium Channels / metabolism
  • Humans
  • Ions
  • Microscopy / methods*
  • Microscopy, Confocal / methods
  • Mucous Membrane / pathology
  • Reproducibility of Results
  • Surface Properties
  • Time Factors


  • Epithelial Sodium Channels
  • Ions
  • Cystic Fibrosis Transmembrane Conductance Regulator