An in vitro triple cell co-culture model with primary cells mimicking the human alveolar epithelial barrier

Abstract

A triple cell co-culture model was recently established by the authors, consisting of either A549 or 16HBE14o– epithelial cells, human blood monocyte-derived macrophages and dendritic cells, which offers the possibility to study the interaction of xenobiotics with those cells. The 16HBE14o– containing co-culture model mimics the airway epithelial barrier, whereas the A549 co-cultures mimic the alveolar type II-like epithelial barrier. The goal of the present work was to establish a new triple cell co-culture model composed of primary alveolar type I-like cells isolated from human lung biopsies (hAEpC) representing a more realistic alveolar epithelial barrier wall, since type I epithelial cells cover >93% of the alveolar surface. Monocultures of A549 and 16HBE14o– were morphologically and functionally compared with the hAEpC using laser scanning microscopy, as well as transmission electron microscopy, and by determining the epithelial integrity. The triple cell co-cultures were characterized using the same methods.It could be shown that the epithelial integrity of hAEpC (mean±SD, 1180±188Ωcm2) was higher than in A549 (172±59Ωcm2) but similar to 16HBE14o– cells (1469±156Ωcm2). The triple cell co-culture model with hAEpC (1113±30Ωcm2) showed the highest integrity compared to the ones with A549 (93±14Ωcm2) and 16HBE14o– (558±267Ωcm2). The tight junction protein zonula occludens-1 in hAEpC and 16HBE14o– were more regularly expressed but not in A549.The epithelial alveolar model with hAEpC combined with two immune cells (i.e. macrophages and dendritic cells) will offer a novel and more realistic cell co-culture system to study possible cell interactions of inhaled xenobiotics and their toxic potential on the human alveolar type I epithelial wall.