Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/5367
The human lung develops as an epithelial outgrowth from the fetal digestive tract around the 5th week of gestation. The complete bronchial tree is formed by repeated branching of epithelial tissue into the surrounding mesenchymal tissue (referred to as stroma in this thesis). Using the VA10 bronchial epithelial cell line, the laboratory has introduced a three dimensional cell culture assay that partially mimics human lung morphogenesis. The structure and cellular composition of the epithelial compartment from the proximal to the distal zone is very distinct, which necessitates characterization of in situ condition to be better able to evaluate the quality of the 3D culture model. Studies on molecular control of airway branching in Drosophila and mice have revealed some key players like the receptor tyrosine kinases FGFR2, the EGFR family and their intracellular pathway regulator, Sprouty2. In contrast, there is limited information on the role of RTKs and their regulators in human lung development.
The aim of this project was to characterize epithelial and stromal compartments of the adult human lung and to explore the expression profile of RTKs, particularly FGFR2, EGFR and ErbB2, in both tissue and 3D culture. My objective was also to analyze if the Sprouty expression correlated with the RTKs expression.
Immunohistochemistry shows that RTKs are expressed in bronchial epithelium and to some extent in alveoli but expression pattern is variable between them. Similar staining pattern is seen for the Sprouty family. Expression pattern of FGFR2 and Sprouty2 in branching structures from 3D cultures correlates well with pattern shown in animal models. Some of the Sprouty antibodies were however promiscuous. Therefore I put effort into establishing mRNA in situ hybridization method at the laboratory, to be better able to evaluate the expression profile of Sprouty proteins in lung tissue.
In summary, my results demonstrate that the 3D culture system can be highly useful to study molecular mechanisms during human lung development and the FGFR2 and Sprouty2 are ideal candidates for initial functional studies.