Abstract: TH-PO0011
Escherichia coli Promotes Calcium Oxalate Stone Growth and Human-Like Stone Architecture in a Novel In Vitro Kidney Stone Model
Session Information
- Mineral Balance: Physiology and Pathophysiology
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 501 Bone and Mineral Metabolism: Basic
Authors
- Schwaderer, Andrew L., Indiana University School of Medicine, Indianapolis, Indiana, United States
- Arregui, Samuel, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Williams, James C., Indiana University School of Medicine, Indianapolis, Indiana, United States
Background
We previously showed that Escherichia coli (E. coli) promotes kidney stone formation in a murine calcium oxalate (CaOx) model. Because murine stones differ markedly from human calculi, we developed a novel in vitro system incorporating CaOx crystals, bacteria, and stone matrix proteins to better model human stone architecture.
Methods
An in vitro system adapted from Ananth et al. (2001) modeled calcium oxalate (CaOx) stone formation. Equal volumes of supersaturated solutions containing oxalate, phosphate, calcium, citrate, magnesium, and physiologic salts were combined to generate CaOx crystals. A fibrin nidus coated with dried CaOx crystals was suspended in a perfused growth chamber at ~37°C with constant stirring for 3 weeks.
Experimental groups included CaOx alone, CaOx with Escherichia coli (CFT073), Proteus mirabilis (CDC PR14), human neutrophil peptide-1 (HNP1), or combinations. Bacteria were added weekly at 1×10^8 CFU/mL. HNP1 was applied weekly at physiologic urinary concentrations (250 pg/mL) for 3 hours before stones were returned to the chamber.
Stones were dried weekly for measurement and analyzed by micro-CT (Skyscan 1172, Bruker). Surface architecture was assessed using a Keyence VK-X3000 3D surface profiler.
Results
Stones exposed only to CaOx demonstrated the lowest growth rate and formed relatively homogeneous mineral structures. In contrast, exposure to bacteria, HNP1, or both produced increasingly heterogeneous stones with inclusions and concentric growth rings resembling human kidney stones. The most organized growth-ring architecture developed in stones exposed to both E. coli and HNP1.
Three-dimensional surface profiling demonstrated substantially increased surface roughness in stones generated in the presence of E. coli compared with CaOx-only controls. Potential mechanisms include bacterial-mediated crystal aggregation, enhanced crystal adherence, or biofilm formation on the stone nidus facilitating additional mineral deposition
Conclusion
These findings provide direct evidence that bacteria promote CaOx stone growth and drive formation of complex stone architecture resembling human nephrolithiasis. This novel in vitro model supports a mechanistic role for bacteria and stone matrix proteins in kidney stone pathogenesis and provides a platform for future studies investigating microbial contributions to stone disease.
Acknowledgment
Supported by NIDDK R01DK146430
Funding
- NIDDK Support