Determination of lung regeneration using an ex vivo tissue slice model

Chronic obstructive pulmonary disease (COPD) is the fourth leading
cause of death worldwide. At the moment no curative treatment is
available. Thus far, lung transplantation is the only option
however donor organ shortage limits its general clinical
application. New therapies are desperately needed. Here, 3D ex vivo
lung tissue cultures (3D-LTC) from diseased murine and human lungs
were applied to study repair and remodelling in high
spatio-temporal resolution. In a first step, the method of 3D-LTC
generation and cultivation was optimized and improved. Cell
viability and proliferation was maintained until day seven. Murine
and human lung samples were examined by histology,
immunofluorescence, spatio-temporal confocal live-cell-imaging, as
well as gene and protein expression analyses to fully characterize
the suitability of the model for signal pathway modulation.
Previous reports demonstrated that Wnt/beta-catenin signal
activation led to attenuation of experimental emphysema in mice
[Kneidinger, et.al., 2011]. TGF-beta is another pathway involved in
COPD and a lack of TGF-beta seems to be related to the
emphysematous changes [Budd, et.al., 2012]. To get insight into
disease underlying mechanisms the COPD-relevant signalling pathways
Wnt/beta-catenin and TGF-beta were activated in 3D-LTC from COPD
patients and emphysematous animals. It was demonstrated that
Wnt/beta-catenin signal activation initiated epithelial repair in
3D-LTC. Moreover, Wnt/beta-catenin pathway activation and alveolar
epithelial type II cell activation significantly correlated with
individual disease stage suggesting that 3D-LTC from patients are
suitable for individual drug validation and therapy prediction.
TGF-beta signalling activation led to the production of
extracellular matrix components and induced expression of
transcription factors and genes involved in
epithelial-to-mesenchymal transition. In conclusion, the model of
3D-LTC established in this thesis allows quantification and
spatio-temporal visualization of regenerative processes in the
lung. It is suitable to validate and give further mechanistical
insight of Wnt/beta-catenin and TGF-beta induced lung repair and
remodelling, as well as treatment response prediction to
individualized therapy. Thus, the 3D-LTC model presents a superior
system for preclinical drug validation.