Modelling Idiopathic Pulmonary Fibrosis In Vitro: Development of novel bioengineered tissue constructs of the alveolar epithelium to investigate IPF pathophysiology

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease, characterised by scarring of lung parenchyma and loss of respiratory function. The aetiology of IPF remains unknown, although several risk factors have been identified that may contribute to disease susceptibility. It now
thought that IPF may develop as a result of repetitive low-grade environmental insults that act upon the alveolar epithelium, in genetically or environmentally susceptible individuals, leading to homeostatic dysregulation and aberrant wound healing within the distal lung.
Current therapeutic approaches are insufficient at preventing disease progression, or reversing architectural distortions to the lung parenchyma. As such, the average life expectancy for IPF patients at the point of clinical diagnosis, is only 4-5 years. The development of novel, more effective pharmacological
therapies is heavily restricted by the limited knowledge of the specific cellular and signalling mediators that drive disease progression. Moreover, there is an absence of pre-clinical models, both in vivo and in vitro, that can accurately recapitulate disease pathobiology. Indeed, many drugs previously validated within
experimental murine models of lung fibrosis, fail to progress beyond phase I and phase II clinical trials.
The aim of this project was to bioengineer novel in vitro models of the normal and IPF alveolar interstitium, that recapitulated the structure and composition of in vivo tissue. Commercially available 3D culture scaffold technologies were first employed to generate a pulmonary interstitial tissue construct, comprised exclusively of tissue-specific human lung fibroblasts and their endogenous, de novo extracellular matrix. This construct was subsequently utilised to support an overlying epithelial compartment, and thus generate alveolar interstitial-epithelial co-culture models. Initial work focussed on the optimisation and characterisation of both model systems, in which IPF fibroblasts were found to excessively deposit and remodel endogenous ECM, and induce alveolar epithelial
dysfunction, thus recapitulating the IPF phenotype. Exogenous stimulation of normal and IPF co-culture models elicited a pro-fibrotic phenotype, characterised by EMT, myofibroblast differentiation and matrisome remodelling. Finally, it was demonstrated that IPF models are a suitable pre-clinical platform to evaluate the anti-fibrotic efficacy of novel compounds, regarding their capacity to modulate ECM remodelling and epithelial permeability.
As such, this thesis presents Alvetex alveolar co-cultures as a robust and reproducible platform to model
idiopathic pulmonary fibrosis, in vitro.