**5. Conclusions**

Basic and translational research on lung biology and pathology can greatly benefit from the development of 3D *in vitro* models that can maintain cell phenotypes and functions in a physiologically relevant way. Lung organoids and lungs-on-chip allow the creation of different kinds of *in vitro* microenvironments (**Figure 2**), that can be useful for the study of specific diseases, and for the elucidation of novel pathogenetic pathways. They represent in fact important translational models for the study of clinically relevant issues, for the identification of novel therapeutic targets, and for preliminary testing of new drugs. The main challenge in future developments is represented by the standardization of integrated protocols for the simultaneous inclusion of extracellular matrix, stromal components, immune cells, and biomechanical cues within 3D *in vitro* models. This step forward would provide a clinically relevant system for lung research, which would include all the actors involved in endogenous responses occurring *in vivo*. Nonetheless, despite several limitations still existing, the complexity of these models has been rapidly increasing in the past decade, and they must be considered as complementary in all respects to *in vivo* studies carried on in animal models.

## **Acknowledgements**

This work was supported by grant # 2015BN82FK from the Italian Ministry of Education, University and Research (MIUR) to Isotta Chimenti.

*Innovative* In Vitro *Models for the Study of Lung Diseases DOI: http://dx.doi.org/10.5772/intechopen.95300*
