Acute and chronic lung diseases are a major cause of global mortality. While pharmacological approaches exist, no therapies are curative. The only option at end-stage disease is lung transplantation which is hampered by a chronic shortage of donor organs. Therefore, there is a high interest to develop alternative approaches to use regenerative medicine approaches to generate new lung tissue in the lab or to deliver cells which can participate in structural repair. In parallel to this clinical need, these new technologies, and the animal models which are used to assess their efficacy, require the development of new evaluation methods. One of the most important methods for evaluating these therapies is histological assessment, as it can provide direct information at the tissue and cellular level information across all stages of the bioengineered tissue: from manufacture through evaluation in pre-clinical animal models. However, many of these potential therapies are comprised of a mix of cells, extracellular matrix and biomaterials (i.e. polymers in the case of soft tissues). Standard histological approaches have been developed for use with native animal and human tissues and organs, based on chemical moieties which are ubiquitous in animal tissues (e.g. amine or carboxylic acid groups). Biomaterials (e.g. synthetic or natural polymers), on the other hand, have diverse chemical moieties that may not always be compatible with standard fixatives and tissue processing. Furthermore, the chemical composition of the solutions used in fixation or tissue processing, even at trace amounts, may alter biomaterials which have been used for bioengineering tissue or in vitro models. Therefore, this thesis aimed to develop new methods to histologically assess native and bioengineered lung tissue, with a particular focus on developing methods which preserve cell-extracellular matrix or cell-biomaterial interactions for light and electron-based microscopy
