Therapeutic effects of adipose-tissue-derived mesenchymal stromal cells and their extracellular vesicles in experimental silicosis

Background: Silicosis is an occupational disease that affects workers who inhale silica particles, leading to extensive lung fibrosis and ultimately causing respiratory failure. Mesenchymal stromal cells (MSCs) have been shown to exert therapeutic effects in lung diseases and represent an alternative treatment for silicosis. Recently, it has been suggested that similar effects can be achieved by the therapeutic use of extracellular vesicles (EVs) obtained from MSCs. The aim of this study was to investigate the effects of adipose-tissue-derived MSCs (AD-MSCs) or their EVs in a model of silicosis. Methods: Silicosis was induced by intratracheal instillation of silica in C57BL/6 mice. After the onset of disease, animals received saline, AD-MSCs, or EVs, intratracheally. Results: At day 30, AD-MSCs and EVs led to a reduction in collagen fiber content, size of granuloma, and in the number of macrophages inside granuloma and in the alveolar septa. In addition, the expression levels of interleukin 1 beta and transforming growth factor beta in the lungs were decreased. Higher dose of EVs also reduced lung static elastance when compared with the untreated silicosis group. Conclusions: Both AD-MSCs and EVs, locally delivered, ameliorated fibrosis and inflammation, but dose-enhanced EVs yielded better therapeutic outcomes in this model of silicosis.