Abstract WP88: In a Pro-inflammatory Environment, Mesenchymal Stromal Cells Exert Anti-inflammatory and Pro-angiogenic Effects on Endothelial Cells

Abstract

Background: Cell-based therapies such as mesenchymal stromal cells (MSCs) have increasingly shown great promise for ischemic stroke recovery. An understudied target of MSCs may be endothelial cells (ECs). Our study explored the interactions between MSCs and ECs and how this interaction alters EC functionality when exposed to an inflammatory cell stimulus. Methods: Primary brain ECs were isolated from postnatal 1-4 day old C57BL/6 mice. Primary MSCs were isolated from the bone marrow of C57BL/6 mice. At passage 3, both the primary cells were individually seeded at 50,000 cells per well. To simulate a stroke-like inflammatory environment, we exposed MSCs and ECs to Lipopolysaccharides (LPS) (doses ranging from 0.01ug/ml to 100ug/ml). 24 hours post-LPS exposure, conditioned media from MSCs was collected and added to the treated ECs. At 24 hours of incubation, media was collected from the ECs and IL-6 and VEGF concentrations were measured using ELISA. Viability of ECs following LPS exposure was measured using MTT assay. Results: Treatment of the ECs using MSC conditioned media significantly reduced the release of IL-6, a pro-inflammatory cytokine at dose ranges of 1ug/ml to 100ug/ml of LPS (Fig. 1A-B). The release of VEGF, a pro-angiogenic cytokine, was significantly increased (Fig. 1C-D). There was no significant change in viability of ECs following different LPS doses (data not shown). Conclusion: MSCs may release soluble factors that modulate the responses of endothelial cells. MSCs exert anti-inflammatory and pro-angiogeneic effects on ECs in a pro-inflammatory setting. These results identify new targets to better understand how MSCs improve recovery in stroke animal models.