TGFBR1 and pulmonary fibrosis: Adipose mesenchymal stem cells (ADSCs) are another source of EVs that have been shown to significantly reduce primary lung injury and pulmonary fibrosis in rat lungs exposed to fine particulate matter less than 2.5 μm (PM2.5), demonstrating that pulmonary fibrosis is mitigated in part by let-7d-5p targeting TGFβ-R1 [94].