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An In Vitro Bladder Model of Catheter-Associated Urinary Tract Infection
Published on: June 24, 2025
Optimal artificial urine formulations for in vitro urolithiasis models
Deok Hyun Han1, Jae Hoon Chung2
1Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Frontiers in Urology
|June 1, 2026
Summary
This study developed artificial urine models to simulate kidney stone formation and assess stent encrustation. The best conditions for maximizing stent deposition involved specific calcium oxalate, uric acid, and bacterial infection models.
Area of Science:
- Biochemistry
- Materials Science
- Urology
Background:
- Urinary tract stones and stent encrustation are significant clinical challenges.
- Standardized in vitro models are needed to study stone formation and stent fouling.
- Current artificial urine models lack standardization for specific stone types.
Purpose of the Study:
- To develop and characterize standardized in vitro artificial urine (AU) models for calcium oxalate (CaOx), uric acid (UA), and infection-related struvite stone environments.
- To identify assay conditions that maximize stent-associated surface deposition while minimizing bulk precipitation.
- To create a platform for evaluating stent materials and anti-encrustation strategies.
Main Methods:
- Formulated AU models with physiologic base composition, modified for disease-specific lithogenic conditions (CaOx, UA, bacterial infection).
- Tested CaOx model with escalating calcium chloride and fixed sodium oxalate.
- Evaluated UA model at varying concentrations and acidic pH.
- Assessed bacterial infection model at different initial pH levels (6.5, 9.0) and a non-bacterial control.
- Immersed commercial stents for 48 hours under CDC biofilm-reactor conditions and quantified surface deposition by weight change.
Main Results:
- CaOx model showed increased deposition with calcium up to 200% (0.98 g/L), then declined due to bulk precipitation.
- UA model exhibited maximal deposition at 600 mg/L.
- Bacterial infection model at preset pH 6.5 yielded the highest weight gain, followed by pH 9.0.
- Non-bacterial alkalinization resulted in negligible deposits.
- Specific conditions (CaCl2 200% + oxalate 80 mg/L, uric acid 600 mg/L, bacterial infection at pH 6.5) maximized stent deposition.
Conclusions:
- Developed stone type-specific AU models offering defined, lab-preparable lithogenic screening conditions.
- Identified optimal assay parameters within a 48-hour reactor for maximizing stent encrustation.
- The developed platform serves as an accelerated screening tool for stent materials, coatings, and anti-encrustation strategies.
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