Progesterone Modulates Protein Cargo in Extracellular Vesicles Released from Bovine Uterine Epithelial Cells

Communication between the womb (uterus) and the developing embryo is essential for successful pregnancy. Tiny particles called extracellular vesicles are released from cells in the uterus and carry proteins and other molecules that help the embryo grow and attach to the uterus. In this study, we investigated how the hormone progesterone influences the contents of extracellular vesicles released from the cells (epithelial cells) that line the cow's uterus. We found that progesterone alters the amount of specific proteins in these vesicles without affecting the number of vesicles released. Many of the altered proteins are involved in preparing the uterus for implantation and supporting embryo development. We also demonstrated that these vesicles can be taken up by early-stage cow embryos. Our findings suggest that progesterone changes in which proteins are packed in these vesicles, helping create a receptive environment for implantation and early development.