A new method for cytodestruction of bladder epithelium using protamine sulfate and urea

Bladder epithelium relies primarily on the presence of a surface glycosaminoglycan (GAG) layer and the structural integrity of cell-cell contact to maintain impermeability to toxic urinary wastes. Previous clinical studies evaluating bladder permeability characteristics in interstitial cystitis patients had indicated that epithelial desquamation occurs after treatment with protamine sulfate (PS) followed by hypertonic urea. The following study was performed using rabbits to further investigate this finding. The urinary bladder was evaluated for optimal treatment conditions for epithelial removal. Protamine sulfate (1 to 10 mg./ml.) and urea (100 to 200 gm./ml.) were instilled into the bladder at volumes ranging from 5 to 60 ml. to that required for near maximum distention. After incubation at room temperature for 15 minutes, the bladders were fixed and evaluated histologically for epithelial removal. The maximum epithelial removal occurred when the bladders were distended, and when PS concentration was 5 to 10 mg./ml. and urea at 200 gm./l. There was greater epithelium removal after repeated treatments. Epithelial cells that were removed were not viable based on Trypan blue staining. There was no significant increase of C14 labeled urea in the plasma after 15 minutes. Rabbits that were followed for 6 weeks after treatment did not show any histological evidence of increased collagen deposition and/or fibrosis. This procedure may have important clinical value since it may remove sufficient bladder epithelium in patients with transitional cell carcinoma to have therapeutic benefit. This offers a realistic option for selective, nontoxic destruction of bladder epithelium.