Endometrial stromal cell signaling and microRNA exosome content in women with adenomyosis.

Adenomyosis is a chronic, estrogen-driven disorder characterized by the presence of endometrial glands and stroma within the myometrium. Despite its significant impact on reproductive health and quality of life, the pathogenesis of the disease remains unclear. Both the glandular and stromal compartments of eutopic endometrium from women with adenomyosis show alterations compared to healthy subjects. However, the molecular mechanisms driving crosstalk between stromal cells and epithelial glands, along with paracrine signaling underlying lesion development and progression, are still poorly understood. Exosomes, small cell-derived carriers and microRNAs, namely non-coding RNA molecules, are crucial to intercellular communication within the endometrium and may elucidate interactions between the two compartments that contribute to adenomyotic lesion formation. To our knowledge, this is the first foundational study to comprehensively isolate and characterize stroma-derived exosomes from women with adenomyosis. Exosome isolation by means of differential ultracentrifugation was validated in 22 samples, including 11 healthy subjects and 11 women with adenomyosis, using nanoparticle tracking analysis, transmission electron microscopy and flow cytometry. Profiling of microRNA in secreted exosomes revealed 10 microRNAs with significantly altered expression in adenomyosis subjects during the menstrual phase compared to controls. Thorough investigations into menstruation-specific molecular mechanisms, as well as predicted target genes and enriched pathways of exosomal microRNAs, offer promising insights into the pathogenesis of adenomyosis, shedding light on the potential mechanisms underlying stromal cell signaling and adenomyotic lesion establishment. This work does, however, have certain drawbacks, including modest sample size and limited representation due to a lack of readily available endometrial biopsies in the menstrual phase. Having done the groundwork in this study, future research should seek to validate these findings in larger cohorts and apply functional assays. Indeed, our findings can serve as a resource to elucidate the role of menstruation-specific stroma-derived microRNA-mediated signaling and its potential impact on adenomyosis development.