Conditioned media from adipose stromal cells limit lipopolysaccharide-induced lung injury, endothelial hyperpermeability and apoptosis.

BACKGROUND: Acute Respiratory Distress Syndrome (ARDS) is a condition that contributes to morbidity and mortality of critically ill patients. We investigated whether factors secreted by adipose stromal cells (ASC) into conditioned media (ASC-CM) will effectively decrease lung injury in the model of lipopolysaccharide (LPS)-induced ARDS. METHODS: To assess the effect of ASC-CM on ARDS indices, intravenous delivery of ASC and ASC-CM to C57Bl/6 mice was carried out 4 h after LPS oropharyngeal aspiration; Evans Blue Dye (EBD) was injected intravenously 1 h prior to animal sacrifice (48 h post-LPS). Lungs were either fixed for histopathology, or used to extract bronchoalveolar lavage fluid (BALF) or EBD. To assess the effect of ASC-CM on endothelial barrier function and apoptosis, human pulmonary artery endothelial cells were treated with ASC-CM for 48-72 h. RESULTS: ASC-CM markedly reduced LPS-induced histopathologic changes of lung, protein extravasation into BALF, and suppressed the secretion of proinflammatory cytokines TNFα and IL6. White Blood Cells (WBC) from BALF of LPS-challenged mice receiving ASC-CM had decreased reactive oxygen species (ROS) generation compared to WBC from LPS-challenged mice receiving control media injection. Treatment of pulmonary endothelial monolayers with ASC-CM significantly suppressed H2O2-induced leakage of FITC dextran and changes in transendothelial resistance, as well as gap formation in endothelial monolayer. ASC-CM exposure reduced the percentage of endothelial cells expressing ICAM-1, and suppressed TNFα-induced expression of E-selectin and cleavage of caspase-3. ASC-CM reduced the endothelial level of pro-apoptotic protein Bim, but did not affect the level of Bcl-2, Bad, or Bad phosphorylation. CONCLUSIONS: Factors secreted by ASC efficiently reduce ARDS indices, endothelial barrier hyperpermeability, and activation of pro-inflammatory and pro-apoptotic pathways in endothelium.

Adipose stromal cells differentiation toward smooth muscle cell phenotype diminishes their vasculogenic activity due to induction of activin A secretion.

Adipose stromal cells (ASCs) support endothelial cell (EC) vasculogenesis through paracrine and cell-contact communications. In addition, ASCs differentiate towards the smooth muscle cell (SMC) phenotype under different stimuli, which prompted their use as a source of mural cells in fabricating small calibre vessels. How ASCs' SMC-lineage commitment affects their subsequent communication with ECs is unknown. The vasculogenic characteristics of human ASCs in progenitor stage and after differentiation towards SMC phenotype were analysed in the present study. Exposure to transforming growth factor ß1 (TGFß1 ) or activin A has induced expression of SMC markers in ASCs. Analysis performed after treatment withdrawal revealed that secretome of pre-differentiated ASCs had a reduced potency to support EC survival and these ASCs had diminished ability to support EC vasculogenesis in vitro. Vascularization of subcutaneous implants carrying a mixture of ECs and ASCs was 50% lower when, instead of control, pre-differentiated ASCs were used. Pre-differentiated ASCs had an inferior mitogenic response to EC-produced factors. Differentiation of ASCs was accompanied by upregulation of vascular endothelial growth factor and a decrease in hepatocyte growth factor (HGF) production; however, addition of HGF to the co-culture incubation media did not improve vasculogenesis. In parallel, ASC treatment with TGFß1 induced secretion of activin A. Augmenting co-culture incubation media with anti-activin A IgG restored the ability of pre-differentiated ASCs to support vasculogenesis to the same degree as control ASCs. The present study suggests that TGFß1 or activin A-induced ASC commitment to SMC phenotype negatively affects the ability of ASCs to support EC vasculogenesis in applications based on EC and ASC co-injection into target tissues. Copyright © 2016 John Wiley & Sons, Ltd.