The impact of human follicular fluid extracellular vesicle subtypes on KGN cells
Follicular fluid extracellular vesicles (FF EVs) mediate communication between oocytes and somatic cells within the ovarian follicle, playing critical roles in follicular development. This study examines the molecular and functional differences between small (SEV) and large (LEV) FF EV subpopulations, focusing on their impacts on KGN tumor-like granulosa cells (GCs). At a specific dose, SEVs reduced estradiol secretion, whereas LEVs enhanced progesterone production, aligning with the physiological shift in steroidogenesis following the luteinizing hormone (LH) surge. SEVs were enriched in miRNAs targeting pathways related to cell cycle regulation and TGF-ß signaling, while LEVs carried higher levels of piRNAs, suggesting a role in maintaining genomic stability in follicular cells. Functional assays in KGN cells revealed that SEVs upregulated genes associated with extracellular matrix (ECM) remodeling and PTK2 signaling while downregulating genes linked to cholesterol biosynthesis and DNA repair. In contrast, LEVs induced upregulation of genes involved in immune functions (VCAM1, C1S) and oxidative stress defense (SOD2). Small RNA-sequencing demonstrated distinct short non-coding RNA (ncRNA) profiles in SEV- and LEV-treated KGN cells, with no overlap in miRNAs potentially delivered by the two subpopulations. These findings underscore the specialized regulatory roles of FF EV subpopulations, offering deeper insights into their contributions to GC function and ovarian physiology.