# Establishment of an artificial urine model in vitro and rat or pig model in vivo to evaluate urinary crystal adherence

## TL;DR

This study developed in vitro and in vivo models to test how well ureteral stents resist crystal adhesion, which can cause complications in patients.

## Contribution

The study introduces a novel artificial urine model and uses rat and pig models to evaluate crystal adherence on ureteral stents.

## Key findings

- Artificial urine model 1 showed significantly more crystal adhesion compared to other models after 3-4 weeks.
- Artificial urine without urea had less pH variability and more crystal adhesion.
- Starting the experiment at pH 6.3 resulted in the highest crystal adhesion to stents.

## Abstract

The current study aimed to establish an experimental model in vitro and in vivo of urinary crystal deposition on the surface of ureteral stents, to evaluate the ability to prevent crystal adhesion. Non-treated ureteral stents were placed in artificial urine under various conditions in vitro. In vivo, ethylene glycol and hydroxyproline were administered orally to rats and pigs, and urinary crystals and urinary Ca were investigated by Inductively Coupled Plasma-Optical Emission Spectrometer. in vitro, during the 3- and 4-week immersion periods, more crystals adhered to the ureteral stent in artificial urine model 1 than the other artificial urine models (p < 0.01). Comparing the presence or absence of urea in the composition of the artificial urine, the artificial urine without urea showed less variability in pH change and more crystal adhesion (p < 0.05). Starting the experiment at pH 6.3 resulted in the highest amount of crystal adhesion to the ureteral stent (p < 0.05). In vivo, urinary crystals and urinary Ca increased in rat and pig experimental models. This experimental model in vitro and in vivo can be used to evaluate the ability to prevent crystal adhesion and deposition in the development of new ureteral stents to reduce ureteral stent-related side effects in patients.