Does technique or material used affect bladder tissue reactions when injecting teflon or silicone paste?

Area of Science:

• Urology
• Biomaterials Science
• Histopathology

Background:

• Submucosal injections of polytetrafluoroethylene (PTFE) and polydimethylsiloxane (PDMS) pastes are used for treating vesicoureteral reflux and urinary incontinence.
• The efficacy and safety of these materials may be influenced by injection technique and material properties, potentially affecting particle migration and tissue response.

Purpose of the Study:

• To investigate the impact of injection technique, paste material (PTFE vs. PDMS), and site pretreatment on local tissue reactions.
• To evaluate the histological outcomes, including bleb location, inflammation, fibrosis, and epithelial necrosis, at various time points post-injection.

Main Methods:

• 44 New Zealand white rabbits were used, undergoing submucosal or bladder muscularis injections of PTFE or PDMS paste.
• Injection sites were pretreated with saline, epinephrine, or doxycycline, or left untreated.
• Bladder biopsies were performed at 1 hour, 1 day, 7 days, 1 month, and 6 months for blinded histological evaluation.

Main Results:

• PTFE injections were more frequently found within the muscularis or lost post-autopsy compared to PDMS.
• Particles were consistently found in retrieved PDMS injection sites.
• Doxycycline pretreatment led to significant early epithelial necrosis; however, no significant differences in inflammation or fibrosis were observed between PTFE and PDMS at later time points.

Conclusions:

• Polydimethylsiloxane (PDMS) paste, when injected correctly, is more likely to remain in the submucosal space compared to polytetrafluoroethylene (PTFE).
• Pretreatment injections can induce early epithelial necrosis.
• Both PTFE and PDMS elicit comparable foreign body reactions over extended periods.