Using 3-Dimensional Cultures to Propagate Genetically Modified Lung Organoids.

Transformed lung organoids have extensive applications in lung cancer modeling and drug screening. Traditional two-dimensional (2D) cultures fail to propagate a large subpopulation of murine primary tumors in vitro. However, three-dimensional (3D) air-liquid interface (ALI) cultures, which are employed to grow normal lung organoids, can be used to efficiently culture cancerous lung tumor cells. Here, we detail a procedure for cultivating genetically modified lung organoids in 3D-ALI cultures. This protocol contains two parts. The first part describes how to transduce lung epithelial cells, which are either freshly sorted from lungs or from actively growing murine organoids, with virus in order to modify gene expression. The target lung cells are incubated with virus for 1-2 h for transduction. Then, the transduced cells are thoroughly washed and mixed with stromal support cells and Matrigel and are loaded into transwell inserts for culture and validated for genetic modifications through downstream assays. The second part describes how to isolate tumor cells growing orthotopically in genetically engineered mouse models to produce organoid cell lines that can be used for ex vivo drug discovery assays. For this protocol, tumors are isolated from lungs of mice, finely chopped and washed. Then, tumor chunks are mixed with Matrigel for 3D-ALI culture. Finally, organoids budding from tumor chunks are trypsinized and passaged to establish an organoid line. Together these two protocols provide a promising platform to study the genesis, progression, and treatment of lung cancer.