Human adipose-derived stem cell exosomes alleviate human respiratory system-related cells damaged by exposure to SO₂ derivatives.

Inhalation burns, especially when combined with thermal burns, can be fatal and significantly increase mortality rate through inhaling hazardous gas. However, there is no specific treatment for inhalation burns except for relieving bronchospasm and cleaning the airways. In particular, inhaled sulfur dioxide (SO₂), a major component of inhalation burns, can easily be hydrated in the respiratory tract to produce sulfurous acid, which subsequently dissociates to form bisulfite and sulfite derivatives. In this study, we intend to assess whether human adipose-derived stem cell (ASC) exosomes rescue respiratory system-related cells damaged by exposure to SO₂ derivatives. We found that the uptake of ASC exosomes was high in human respiratory systemrelated cells and they rescue decreased proliferation of cells damaged by treatment with SO₂ derivatives. In human pulmonary endothelial cells (HPMECs), total tubule length was increased by pre-treatment of ASC exosomes through an in vitro angiogenesis assay. Besides, we confirmed that ASC exosomes alleviate increased expression of inflammation-related genes by treatment of SO₂ derivatives in primary respiratory epithelial cells. Taken together, these results suggest that ASC exosomes have potential in regeneration of human respiratory system-related cells damaged by inhalation burns, which currently lack specific treatment methods.