Glycosaminoglycan content of human bladders: a method of analysis using cold-cup biopsies

A glycocalyx layer composed of glycosaminoglycans (GAGs) and other molecules lines the transitional epithelium of the urinary bladder. This layer forms a barrier between the transitional cells and urinary bladder environment and is believed to help prevent the adherence of bacteria, minerals and carcinogens. Investigators postulate that quantitative and/or qualitative defects in the GAG component may be responsible for a spectrum of acute and chronic disease processes ranging from urinary tract infections to cancer. While the presence of epithelium GAGs has been confirmed biochemically and histochemically, few rigorous characterizations have been performed. This study establishes the methodology and feasibility of using routine cold-cup biopsies from cadaveric human bladders for GAG analysis and establishes baseline contents of the sulfated and non-sulfated GAGs in the urinary bladder glycocalyx. Using detergent extraction, the GAGs from cold-cup biopsies (n = 34) from four cadaveric bladders were isolated. The isolates were subjected to two colorimetric assays to quantify both sulfated and non-sulfated GAGs. The nonsulfated GAG content of the bladder epithelium ranged from 2.15 × 10−4 to 5.50 × 10−4 mmol/kg of dry, defatted bladder. The sulfated GAG content ranged from 2.00 × 10−1 to 7.40 × 10−1 mmol/kg of dry, defatted bladder. These values are consistent with reports found in the literature using electrophoresis on full-thickness human bladder specimens. The GAG content of human bladder epithelium can be readily and accurately characterized from cold-cup biopsy samples. Our future plans involve using this routinely used technique to analyze samples from live control and disease-state bladders thereby demonstrating any quantitative and/or qualitative differences in GAG constituents.