Properties of Hydrogel Composites for the Inkjet-printed in vitro Alveolar Model

There have been needs for in vitro lung models to rapidly develop new drug or to analyze the association between harmful factors (i.e. virus, fine dust, and chemicals) and various lung diseases. In particular, alveolus, the smallest unit in which gas exchange occurs in the lung, is very thin tissue composed of three layers: vascular endothelial cells, basement membrane, and epithelial cells. Our research group succeeded in fabricating inkjet-printed alveolar model with thin and three-layered structure. We have used collagen as the basement membrane material. However, due to its weak physical properties, shrinkage and degradation of the collagen hydrogel have occurred during the long-term culture of tissues. In this study, we blended collagen type Ⅰ, gelatin methacryloyl, and polyacrylamide to fabricate hydrogels with good cell affinity and high mechanical properties. The blended hydrogel had higher mechanical properties than collagen hydrogel. Most of the cells in blended hydrogel were alive after encapsulation, but cell spreading could not be observed like in the collagen hydrogel. Additional study will be conducted for improvement of biocompatibility.2