Extracellular vesicles in urine of women with but not without kidney stones manifest patterns similar to men: A case control study

Abstract

Background: The lifetime incidence of kidney stones is about two times greater in men compared to women. Extracellular vesicles (EVs) shed from activated cells are present in the urine and may reflect or even mediate renal physiology and/or pathology. This study was designed to standardize methodology to characterize urinary EVs by digital flow cytometry and to identify possible sex differences in EVs in persons with and without their first symptomatic kidney stones. Methods: Twenty-four-hour urine collections were obtained from persons presenting with their first kidney stone episode (n∈=∈50 women, 60 men; age 19-76 years) and sex- and age-matched controls from the general population (n∈=∈24 women, 36 men). Results: Standardization: Size of EV was variable within all groups. EV positivity was verified with two fluorophores for surface phosphatidylserine and/or using two different protein markers specific for renal-specific cells. The number of phosphatidylserine- and exosome marker-positive EVs did not correlate with urine osmolality and were similar in fresh vs. frozen and between two sequential urine collections from the same individual. Sex differences: Urine from women controls contained greater (P∈