Coculture of hAT2s with adult human lung mesenchyme (AHLM) rich in PDGFRA+ fibroblast populations results in their transdifferentiation to KRT5+ basal cells, recapitulating events in IPF, in which AEC2s are lost and KRT5+ metaplastic alveolar basal cells appear. This evidence concerns the gene KRT5 and idiopathic pulmonary fibrosis.