Porcine uterine luminal fluid-derived extracellular vesicles improve conceptus-endometrial interaction during implantation

Successful implantation of porcine conceptus requires synergistic interaction with various signal molecules in the maternal uterus. Extracellular vesicles (EVs) in uterine luminal fluid (ULF) of mice play important roles in conceptus development. However, studies have not explored the roles of extracellular vesicles (EV) in ULF of pigs. The aim of this study was to identify characteristics, origin, and roles of ULFderived EVs on day 9 of the estrous cycle and on day 9,12 and 15 of pregnancy in pigs. Western blot, BCA assay and HE staining analysis showed increase in EVs concentration in ULF began from day 12 of pregnancy. Immunofluorescence staining and transmission electron microscopy analysis showed that EVs were mainly derived from endometrial epithelial cells. Fluorescent labeling, CCK-8 and transwell migration assays showed that these EVs were delivered to the trophoblast or parthenogenetic activation embryos to regulate proliferation and migration of trophoblast cells. A total of 305 miRNAs were identified using small RNA sequencing analysis. Functional enrichment analysis showed that miRNAs in these EVs potentially play vital regulatory functions in EV transportation or conceptus implantation. QRT-PCR analysis was used to further verify the RNA-seq data. The findings of this study provide information on the functions of porcine ULF-derived EVs and provide a reference dataset for future translational studies on porcine ULF-derived EVs. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study investigated the characteristics, origin, and roles of uterine luminal fluid-derived extracellular vesicles (EVs) in porcine conceptus implantation. The EVs were found to mainly originate from endometrial epithelial cells, with an increase in concentration starting from day 12 of pregnancy. Functional enrichment analysis revealed that the miRNAs in these EVs potentially regulate EV transportation or conceptus implantation, providing important insights for future translational studies on porcine EVs.