Advances and Challenges in Recapitulating Human Pulmonary Systems: At the Cusp of Biology and Materials.

The aim of this review is to provide an overview of physiologically relevant microengineered lung-on-a-chip (LoC) platforms for a variety of different biomedical applications with emphasis on drug screening. First, a brief outline of lung anatomy and physiology is presented followed by discussion of the lung parenchyma and its extracellular matrix. Next, we point out the technical challenges in recapitulating the complexity of lung in conventional static two-dimensional microenvironments and the need for alternate lung platforms. The importance of scaling laws is also emphasized in designing these in vitro microengineered lung platforms. The review then discusses current LoC platforms that have been used for testing the efficacy of drugs or as model systems for investigating disorders of the lung parenchyma. Finally, the design parameters in developing an ideal physiologically relevant LoC platform are presented. As this emerging field of organ-on-a-chip can serve an alternative platform for animal testing of drugs or modeling human diseases in vitro, it has significant potential to impact the future of pharmaceutical research.