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Attachment sites for particles in the urinary tract
C F Verkoelen1, B G Van Der Boom, D J Kok
1Department of Urology, Erasmus University and Academic Hospital Dijkzigt, Rotterdam, The Netherlands. Verkoelen@uro.fgg.eur.nl
Journal of the American Society of Nephrology : JASN
|November 30, 1999
Summary
Crystal adherence to kidney cells initiates kidney stone formation. This study investigated cell surface molecules, finding sialic acid abundant but phosphatidylserine absent on cells binding calcium oxalate crystals.
Area of Science:
- Nephrology
- Cell Biology
- Biochemistry
Background:
- Nephrolithiasis (kidney stone formation) begins with crystal adherence to renal tubule epithelial cells.
- The specific cell surface molecules mediating this crystal attachment remain largely unknown.
- Calcium oxalate monohydrate crystals adhere to specific kidney cell culture conditions.
Purpose of the Study:
- To investigate the role of phosphatidylserine (PS) and sialic acid in calcium oxalate monohydrate crystal adherence to kidney cells.
- To determine if these molecules are enriched on kidney cells that exhibit crystal binding.
- To utilize a Madin-Darby canine kidney-I cell culture model to study crystal-cell interactions.
Main Methods:
- Utilized FITC-annexin V to detect phosphatidylserine (PS) on cell surfaces.
- Employed Sambucus nigra lectin to identify (alpha2,6)-linked sialic acid residues.
- Assessed crystal binding in subconfluent and confluent Madin-Darby canine kidney-I cell cultures.
- Confirmed lectin specificity using N-acetylneuraminyl-lactose blocking.
Main Results:
- Phosphatidylserine (PS) was not detected on the surface of proliferating or growth-inhibited kidney cells without cytotoxic agent treatment.
- Abundant (alpha2,6)-linked sialic acid residues were present on both subconfluent and confluent kidney cell cultures.
- These findings suggest PS is unlikely to be involved in crystal adherence to maturing kidney cells.
Conclusions:
- The study questions the role of cell surface-associated sialylated glycoconjugates in calcium oxalate monohydrate crystal adherence.
- Phosphatidylserine (PS) does not appear to be a primary receptor for crystal binding in this model.
- Further research is needed to elucidate the exact mechanisms of crystal-tubule epithelial cell interactions in nephrolithiasis.