Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/5347
The lung epithelium develops through branching morphogenesis from the fetal digestive tract, and is divided into a proximal conducting zone, and distal transitional and respiratory zones. At least eight morphologically distinct epithelial cell types have been described in the human respiratory epithelium, including basal cells. Bronchial-derived basal cells have been suggested as candidate stem cells in the human lungs. Due to a lack of representative cell lines and culture models, it has been difficult to recapitulate human lung morphogenesis in vitro. Recent studies indicate that endothelial cells are instrumental for organ development and for regulation of stem cells in organs such as the liver, pancreas and brain. A human bronchial basal-like cell line, referred to as VA10, has recently been developed in our laboratory. In this project I show that VA10, when co-cultured with human umbilical vein endothelial cells in a novel three-dimensional (3D) culture model, show increased proliferation followed with marked branching morphogenesis, either by colonies fusing or from a single cell clone. Interestingly, the bronchio-alveolar phenotype generated in 3D co-culture show differentiation toward alveolar type II cells, as judged by immunostaining against proSurfactantProtein-C, a specific marker for these cells. To test if branching morphogenesis occurred in co-culture with other lung epithelial cells, I cultured the widely used alveolar type II cell line A549 together with endothelial cells. The control cell line showed no branching morphogenesis.
In summary, I have established a novel co-culture model where endothelial cells induce branching morphogenesis in VA10 lung epithelial cells. These structures are reminiscent of bronchio-alveolar structures in vivo. This model can be used to study the mechanisms behind branching morphogenesis to investigate the heterotypic cell-cell interactions and cancer progression in the human lung.