BACKGROUND
Endometriosis is a debilitating disease affecting 10% of women of reproductive age characterised by the ectopic growth of endometrial-like lesions, often in the peritoneal cavity. Diagnostic delays are common due to the requirement of invasive laparoscopy and no clinically useful biomarkers exist. Small extracellular vesicles (sEV), secreted by cells as intercellular messengers, carry unique cargo signatures, have pathogenic roles (e.g., in metastasis) and could have biomarker potential.
AIM
To identify differentially expressed cargo proteins in sEV from peritoneal fluid (PF) and peripheral blood (PB) of endometriosis patients compared to non-endometriosis patients and determine their correlation within these fluids.
METHODS
We collected matched PF and PB samples from patients undergoing laparoscopy and grouped them based on endometriosis presence or absence. sEV were isolated by differential ultracentrifugation and validated for universal sEV markers using flow cytometry and Western Blotting. Particle morphology was observed with Transmission Electron Microscopy (TEM) and the concentration and size distribution measured by nanoparticle tracking assay (NTA). Quantitative Tandem Mass Tag (TMT) LC-MS/MS will be used to characterise sEV proteomes and determine differentially expressed proteins between groups and fluids.
RESULTS
N=13 PF and N=12 (paired) blood samples have been collected from N=6 controls and N=7 endometriosis patients (mean age 37 and 32 years, respectively). Validation TEM analyses showed vesicles with a cup-shaped morphology typical of sEV. The mode particle diameters were 120.5-211.7 nm for PF preparations and 107.3-151.7 nm for PB, within the expected range, with a mean particle concentration of 1.06 x 1013 particles/mL for PF and 2.29 x 1011 particles/mL for blood, respectively. Preparations were positive for Syntenin-1, TSG101, CD9, CD63 and CD81, indicative of sEV. Proteomic analysis is ongoing.
CONCLUSION
sEV have been successfully isolated from PF and blood. We expect to find endometriosis-specific sEV which could serve as biomarkers of endometriosis.