Routinely adopted in vitro models of the respiratory tract do not reproduce the complexity associated in vivo with the cellular milieu, such as the presence of an extracellular matrix (ECM), the crosstalk between multiple cell types, and the inclusion of physiological mechanical stimuli. In this work, different strategies were assessed for the development of a biomimetic, high-throughput in vitro model of the human primary and secondary bronchi, replicating the complexity of the cellular environment as observed in vivo whilst maintaining cost-efficiency and reproducibility.

A first strategy centred on the seeding of human bronchial epithelial cells (HBECs) on decellularised bronchial tissue. However, low cell adherence on the tissue-derived scaffolds was reported. A second approach was based on the use of a commercial decellularised lung-derived hydrogel termed “DLH”. Whilst HBECs adhered on the hydrogel, they did not reach confluency. A third strategy was centred on the use of commercial high-throughput microfluidic chips. In these platforms, HBECs adhered and proliferated. Additionally, the inclusion of fluid flow increased cell survival and proliferation. However, issues associated with the contraction of the hydrogel included in the platforms and cell death at late timepoints impeded the onset of mucociliary differentiation. Finally, a fourth strategy centred on the use of high-throughput screening (HTS), 96-well plate-format transwell® systems seeded with HBECs, in co-culture with human lung fibroblasts (HLFs) seeded on DLH. The DLH did not have any adverse paracrine effects on the mucociliary differentiation of HBECs. However, variable results were obtained with regards to the seeding of HLFs on the DLH, as the cells displayed a spindle-like or a circular shape in separate experiments. Whilst further optimisation is necessary, the combination of HBECs, HLFs and DLH on HTS transwell® systems proved to be a promising strategy for the development of a biomimetic bronchial in vitro model.