Lung extracellular matrix hydrogels promote the secretion of mesenchymal stromal cells-derived exosomes

Mesenchymal stromal cells (MSCs) have immunomodulatory and tissue regenerative properties. Recently, different studies have reported that the MSCs behavior and secretome is largely influenced by the physicochemical properties of the culture substrate. In fact, many beneficial effects of MSCs are mediated through exosomes which are considered a promising treatment option for respiratory diseases. However, the impact of physiomimetic lung-extracellular matrix derived hydrogels (L-HG) on their secretome is unknown. Here, we aim to assess the effect of physiomimetic L-HG on exosome release. To this end, human MSCs were cultured on three different substrates: porcine decellularized L-HG (20 mg/mL), type I collagen hydrogel (10 mg/mL) and conventional tissue culture plate (TCP). Exosomes were isolated by ultracentrifugation and characterized by western blotting using Flotillin-1 and Alix markers. After 72 h, the release of exosomes was very similar in MSCs cultured on collagen hydrogel and plastic. However, MSCs cultured on L-HG exhibited a 4.2- and 3.7-fold increase (p<0.05 and p<0.001) in exosome release measured by Flotillin-1 and Alix, respectively, as compared to conventional plastic conditions. In conclusion, we found that cell L-HG substrate strongly enhances the exosome secretion of MSCs potentially modulating their therapeutic effects. Further studies are still needed to characterize exosome composition and their mechanisms of action when treating in respiratory diseases.