title: Permeation of insulin, calcitonin and exenatide across Caco-2 monolayers: measurement using a rapid, 3-day system.
abstract: OBJECTIVE
  Caco-2 monolayers are one of the most widely used in vitro models for prediction of intestinal permeability of therapeutic molecules. However, the conventional Caco-2 monolayer model has several drawbacks including labor-intensive culture process, unphysiological growth conditions, lack of reproducibility and limited throughput. Here, we report on the use of 3-day Caco-2 monolayers for assessing permeability of polypeptide drugs.
  
  
  METHODS
  The 3-day monolayers were grown in a commercially available transwell set-up, which facilitates rapid development of the Caco-2 monolayers in an intestinal epithelial differentiation mimicking environment. This set-up included use of serum-free medium of defined composition with supplements such as butyric acid, hormones, growth factors, and other metabolites, reported to regulate the differentiation of intestinal epithelial cells in vivo. We measured permeability of 3 different therapeutic polypeptides; insulin, calcitonin, and exenatide across the monolayer.
  
  
  RESULTS
  Preliminary validation of the monolayer was carried out by confirming dose-dependent permeation of FITC-insulin and sulforhodamine-B. Transport of insulin, calcitonin, and exenatide measured at different loading concentrations suggests that the permeability values obtained with 3-day cultures resemble more closely the values obtained with ex vivo models compared to permeability values obtained with conventional 21-day cultures.
  
  
  CONCLUSIONS
  Short-term 3-day Caco-2 monolayers provide new opportunities for developing reproducible and high-throughput models for screening of therapeutic macromolecules for oral absorption.
authors.affiliation: Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California, USA.
authors.forename: Vivek
authors.initials: V
authors.lastname: Gupta
authors.forename: Nishit
authors.initials: N
authors.lastname: Doshi
authors.forename: Samir
authors.initials: S
authors.lastname: Mitragotri
mesh_terms: D000704:Analysis of Variance; D018938:Caco-2 Cells; D002116:Calcitonin / Q000378:metabolism / Q000493:pharmacokinetics*; D002463:Cell Membrane Permeability / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D017097:Electric Impedance; D000077270:Exenatide; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000493:pharmacokinetics*; D007408:Intestinal Absorption / Q000502:physiology*; D008954:Models, Biological; D010455:Peptides / Q000378:metabolism / Q000493:pharmacokinetics*; D012235:Rhodamines / Q000493:pharmacokinetics; D014688:Venoms / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D007328:Insulin; D010455:Peptides; D012235:Rhodamines; D014688:Venoms; C022027:lissamine rhodamine B; D002116:Calcitonin; D000077270:Exenatide