Sex differences in urinary extracellular vesicles originating from the genitourinary system in health and disease

Urinary extracellular vesicles (uEVs) have risen to the forefront as a source of biomarkers in urine, a biofluid that can be obtained noninvasively in large quantities. These lipid bilayer-bound, anucleate particles contain molecular cargo that may reflect the pathology of disease processes affecting the urogenital and reproductive systems. Urinary EVs can be derived from a variety of organs including the kidney, bladder, and urethra, as well as the testis, epididymis, vas deferens, prostate, and seminal vesicles in males, or the uterus, vagina, and placenta (during pregnancy) in females, as well as from microbiota present in the bladder or urogenital tract, leading to differences in biomolecular cargo based on sex. Hormonal cycles, circadian rhythms, age, and stress might further influence sex differences in uEVs. Despite growing interest in uEVs as biomarkers for renal and urological diseases, the majority of clinical studies to date have relied on urine samples from male-dominant cohorts, including investigations of sex chromosome-linked disorders. This sampling bias has contributed to a significant knowledge gap regarding sex-specific differences in uEV composition and function, which may critically influence disease mechanisms, diagnostic accuracy, and therapeutic targeting. Addressing this gap is essential for advancing the translational relevance and inclusivity of uEV-based research. This state-of-the-art review focuses on the current literature comparing male versus female uEVs using a variety of orthogonal methods across different studies. We also provide insights to address variability and improve rigor and reproducibility in uEV studies targeting both men's and women's health disorders, to move this field forward.