Impact of low oxygen on the secretome of human adipose-derived stromal/stem cell primary cultures.

Tissue fibrosis can lead to organ dysfunction, patient morbidity, and mortality. Adipose-derived Stromal/stem Cells (ASCs) represent a potential therapeutic. Immediately following grafting, ASCs would reside in a lower O2 environment. ASC secretome was examined under 5% O2 ("low O2") and 21% O2 ("ambient O2") culture conditions. ASCs from five female donors were cultured in low or ambient O2 conditions for 3 days and pooled conditioned medium was compared by two-dimensional liquid chromatography and tandem mass spectrometry (2D-LC-MS/MS). Of 71 proteins identified, five proteins involved in extracellular matrix (ECM) remodeling exhibited ≥2-fold decrease under low O2 culture and were confirmed by Western immunoblot and qRT-PCR: fibronectin 1, TGF-β1-induced protein (βig-h3), osteonectin, and collagens type 1α1 and α2. ELISAs performed using 10 donors also confirmed significant decreases during low O2 culture in 4-6 ASC donors. For low abundant proteins, a 36 cytokine/chemokine array was performed. Fifteen cytokines/chemokines including Type 2 cytokines IL-13, MCP-1, and CD40 ligand were detected in ambient O2 ASC medium. IL-6 was detected in low O2 but not ambient O2 ASC medium. These findings demonstrate that low O2 ASC exposure resulted in reduced ECM protein and Type 2 cytokine secretions that are significant with regard to inflammation in fibrosis.