Abstract: SA-PO298
Water Loading Increases Urinary Extracellular Vesicle Size but Not Excretion Rate
Session Information
- Fluid and Electrolytes: Basic - II
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid and Electrolytes
- 901 Fluid and Electrolytes: Basic
Authors
- Blijdorp, Charles J., Erasmus Medical Center, Rotterdam, Netherlands
- Hartjes, Thomas, Erasmus Medical Center, Rotterdam, Netherlands
- Hoenderop, Joost, Radboud university medical center, Nijmegen, Netherlands
- Bindels, René J., Radboud university medical center, Nijmegen, Netherlands
- Van royen, Martin E., Erasmus Medical Center, Rotterdam, Netherlands
- Cuevas, Catherina A., Erasmus Medical Center, Rotterdam, Netherlands
- Severs, David, Erasmus Medical Center, Rotterdam, Netherlands
- Hoorn, Ewout J., Erasmus Medical Center, Rotterdam, Netherlands
Background
Urinary extracellular vesicles (uEVs) are a promising source of kidney biomarkers, but the factors influencing uEV size and excretion rate are unknown. Here, we studied the effect of water loading on uEV size and excretion rate.
Methods
We performed a water loading test (20 ml/kg) in healthy men (n = 11) and isolated uEVs from whole urine at 6 time-points. uEVs were quantified using nanoparticle tracking analysis (NTA), a time-resolved fluorescence immunoassay that isolates CD9+ uEVs (CD9-TRFIA), and EVQuant, a novel technique that counts individual fluorescently labeled EVs after immobilization in a matrix.
Results
While EVQuant and CD9-TRFIA demonstrated that the excretion rate of uEVs was constant during water loading, NTA suggested a significant increase of 50% by the intervention (p<0.0001). Subsequently, we found on NTA that the size of uEVs generally increased (p<0.0001, Figure). This size increase was confirmed by EM (n= 4, p<0.001, Figure).
Conclusion
Water loading increases uEV size but not excretion rate. A lower urine osmolality may cause water to move into EVs. This phenomenon interferes with uEV quantification by NTA and is an important caveat in uEV studies.
Funding
- Private Foundation Support