Infertility is increasing world-wide with one in 30 pregnancies in Australia now achieved by assisted reproductive technologies. Embryo implantation requires close synchrony of development between the trophoblast and the endometrium which is receptive for implantation for only~4 days in each menstrual cycle. Inability of the endometrium to produce appropriate signals is a major cause for female infertility and IVF failure. Exosomes, 30nm-100nm vesicles containing proteins and miRNAs, are released from many cell surfaces and are thought to mediate some cell-cell communication.We hypothesized that exosomes released from the endometrial surface into the uterine cavity may provide signals that promote embryo implantation. Any disturbance of this release or alterations in exosome contents may result in infertility. As a first step we aimed to determine whether exosomal markers can be detected on endometrial epithelium and whether they are released by endometrial epithelial cells. Exosomal markers (CD9, CD63, and CD81) were detected immunohistochemically on human endometrial epithelium. Potential crude exosome fractions were prepared from endometrial cell culture medium by differential centrifugation to 100,000g. Fluorescence Activated Cell Sorting (FACS) demonstrated marker-positive exosomes. Similarly, exosomes were indentified in uterine fluid obtained by lavage.
This data shows for the first time that exosomes are release from endometrial epithelium, into the uterine microenvironment of implantation.The functional importance is the topic of ongoing studies.