Abstract Rationale Sepsis is a life-threatening condition characterized by organ dysfunction and affecting nearly 50 million people globally each year. Sepsis frequently results from acute lung infection or injury. Mesenchymal stem cells (MSCs) based therapies have demonstrated potential for treating sepsis and pneumonia; however, their clinical efficacy remains limited by complex pathophysiology of the septic microenvironment including the hyperinflammatory state. Preconditioning MSCs with serum from either healthy donors or sepsis patients may reveal the MSCs’ therapeutic potential in the septic microenvironment and provide insights for developing novel therapies for sepsis-induced lung injury. Methods Bone marrow-derived MSCs (BM-MSCs) were co-cultured with LPS/cytomix-stimulated buffy coats (n = 8) to generate septic plasma. BM-MSCs, induced pluripotent stem cell-derived MSCs (iMSCs-WT), and iMSCs overexpressing IL-4/IL-10 were then cultured with serum from healthy donors or sepsis patients. Conditioned media (CM) was collected and analyzed for VEGF secretion by ELISA. The functional effect of CM on alveolar repair was assessed using an A549 epithelial cell wound healing (scratch) assay, wound closure was quantified by measuring relative wound width at 3-hour intervals. Results BM-MSCs co-culture with buffy coats, regardless of LPS/cytomix stimulation, significantly increased VEGF concentration in plasma. Stimulation of BM-MSCs with serum from healthy donors or sepsis patients elevated VEGF secretion in CM. Functionally, CM from healthy-serum-stimulated BM-MSCs enhanced wound closure, while CM from sepsis-serum-stimulated BM-MSCs showed less beneficial effect. CM from healthy-serum-stimulated iMSCs-WT and iMSCs IL-4/IL-10 enhanced wound closure, but there was no difference between iMSCs-WT and iMSCs IL-4/IL-10; CM from sepsis-serum-stimulated iMSCs-WT and iMSCs IL-4/IL-10 showed no beneficial effect and no significant difference. Conclusion These findings indicate that the therapeutic potential of MSCs to heal lung wounds via paracrine mechanisms is significantly more effective in a healthy serum microenvironment compared to the septic one, sepsis patient microenvironment diminishes MSCs pro-healing activity. Furthermore, MSCs mediated promotion of alveolar epithelial cell migration appears to be independent of an anti-inflammatory cytokine environment. This abstract is funded by: China Scholarship Council
Shi et al. (Fri,) studied this question.