In the first examination of extracellular vesicles (EVs) in primate cervicovaginal secretions, including those of a macaque with endometriosis published in the journal BMC Veterinary Research, a team of researchers demonstrated that additional research is justified to determine whether quantification of EVs—or their molecular cargo—in cervicovaginal lavage and vaginal swabs may provide a novel, relatively non-invasive diagnostic for endometrial disease or other reproductive tract diseases.
Endometriosis is a benign but debilitating disease of humans and primates that affects the reproductive tract and has a reported incidence rate of up to 10 % in females of reproductive age. There is no consensus on early, non-invasive diagnostic methods for endometriosis, and diagnostic markers have been sought in peritoneal, follicular and endometrial fluid, urine, blood cells and cell-free fractions.
Extracellular vesicles (EVs, including exosomes and microvesicles) are found in every biofluid examined, carry cargo including proteins and RNA, and may participate in intercellular signaling. Within the past decade, extracellular vesicles have emerged as important mediators of intercellular communication, and are involved in the transmission of biological signals between cells in both prokaryotes and higher eukaryotes to regulate a diverse range of biological processes. In addition, pathophysiological roles for extracellular vesicles are beginning to be recognized in many diseases. However, little is known about EVs in the cervicovaginal compartment, including the effects of reproductive tract disease on quantity and quality of EVs.
In the study titled “Potential role of cervicovaginal extracellular particles in diagnosis of endometriosis”, Kenneth Witwer from The Johns Hopkins University School of Medicine in Baltimore, USA and colleagues report the case of a 9-year-old rhesus macaque that was diagnosed with endometriosis at The Johns Hopkins University School of Medicine in September 2014. The diagnosis was confirmed by a Ultrasound-guided fine needle aspiration of a cyst and subsequent laparotomy.
The animal was sent to necropsy following euthanasia for humane reasons, and the researchers obtained perimortem vaginal swabs and cervicovaginal lavages.
The researchers used a combination of methods, such as NanoSight visualization technology and ultracentrifugation, to quantify the numbers of EVs from each sample. These samples were then compared to populations of EVs from other, reproductively normal macaques. Fewer EVs were recovered from the endometriosis samples in comparison to those from reproductively healthy individuals.
The results showed that nanoparticle tracking analysis of extracellular particles including EVs in cervicovaginal samples associated with a verified case of an ongoing endometrial disease process. In samples collected by both lavage and swab, particle concentration was markedly decreased in an endometriosis situation, when compared to reproductively healthy animals.
Based on the findings, researchers suggest that particles in the cervicovaginal compartment may provide novel, minimally invasive diagnostic tools for reproductive tract disease. According to the researchers, these results will spur larger studies in animal models of endometriosis as well as in human cohorts.