Inhalation of Lung Spheroid Cell-Secreted Factors and Exosomes Promotes Therapeutic Lung Repair in Rodent Models of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal form of interstitial lung disease in which persistent injury results in scar tissue formation. As fibrosis thickens, the lung tissue becomes stiff and losses the ability to facilitate gas exchange and provide cells with needed oxygen. Currently, IPF has few treatment options and no effective therapies, aside from lung transplant. Here we present a series of studies utilizing lung spheroid cell-derived conditioned media (LSC-CM) and exosomes (LSC-EXO) to treat different rodent models of lung injury and fibrosis. Inhalation treatment was given for seven consecutive days via a nebulizer for clinical relevance. Results revealed that LSC-CM and LSC-EXO treatments could attenuate and resolve bleomycin- and silica-induced fibrosis by reestablishing normal alveolar structure, decreasing collagen accumulation, and myofibroblast proliferation. In addition, LSC-CM and LSC-EXOs exhibited superior therapeutic benefits than their counterparts derived from bone marrow mesenchymal stem cells. LSC-CM and LSC-EXOs provide promising therapeutic options for pulmonary fibrosis. Exosomes were collected and purified from human lung spheroid cells (LSCs) and mesenchymal stem cells (MSCs) and their small RNAs were sequenced on a Nextseq500 sequencer (Illumina) using 45bp single-end reads.