In summary, we described here the development and thorough characterization of an in vitro lung fibrosis model and demonstrated that it i) works autonomously, i.e., no added pro-fibrotic stimulants such as TGF-β are required; ii) depends on direct EC-FB contact; iii) develops into a fibrotic condition progressively and synchronously; and iv) leads to dynamic phenotype changes of EC and FB that are very similar to cells associated with progressive fibrogenic changes in patients with IPF. This evidence concerns the gene TGFB1 and idiopathic pulmonary fibrosis.