Microvesicles secreted from equine amniotic-derived cells and their role in in vitro equine endometritis model

Endometritis are pathologies that reduce conception rate and increase delivery-to-conception intervals. Many treatments have been proposed to treat or prevent endometritis but in view of the embryo-maternal interaction, a different approach to the treatment of endometritis could be represented by regenerative medicine. It is known that paracrine mechanism between mesenchymal stem cells and target cells exists and may involve microvesicles (MVs) as an integral component of cell-to-cell communication during tissue regeneration. Based on this hypothesis, this in vitro study aims to understand the efficacy of MVs in a model of endometrial inflammation in view of potential application in vivo. Presence and type of MVs secreted by amniotic derived cells (AMCs) was investigated and the response of endometrial cells to MVs was studied using a dose-response curve at different concentrations (10-20-40-50x106 MVs/ml) and times (24, 48 and 72h). Moreover, the ability of MVs to counteract in vitro inflammation of endometrial cells induced by lipopolysaccharide (LPS) was studied through the rate of apoptosis and prolificacy, the expression of some pro-inflammatory genes such as metallopeptidase (MPP) 1 and 9, IL-1β, IL-6 and TNF-α and the release of IL-6, TGF-β and TNF-α. Results show that AMCs secrete MVs ranging in size from 100-200 nm. The uptake of MVs is gradual over time but peak at 72h. MVs decrease apoptosis rate, increase prolificacy rate, down-regulate gene expression and reduce secretion of pro-inflammatory cytokines after treatment with LPS. MiRNA 335, 146 and 26, present in these MVs, might modulate expression of the genes involved in the study.