Objective:During the last decade years,Caco-2 cell monolayers have been used as an intestinal model to evaluate the effect of delivery systems on drug permeation via transcellular and paracellular transport.While it lacks goblet,mucus-secreting and M-cells.In order to better simulate the endosomatic environment in vitro,HT-29 subclones have been used in co-culture with Caco-2 cells to mimic the small intestinal epithelial layer.The aim of this study was to evaluate the transport properties of solid lipid nanoparticles (SLN) across Caco-2 and mucus-secreting Caco-2/HT29 co-culture cell monolayers.