Collagen Remodeling and Suburethral Inflammation Might Account for Preserved Anti-incontinence Effects of Cut Polypropylene Sling in Rat Model

Abstract

OBJECTIVES To determine whether the inflammatory responses or collagen remodeling in suburethral tissue could have contributed to the preserved anti-incontinence effects of a cut polypropylene sling. METHODS Stress urinary incontinence was created in 60 age-matched female Sprague-Dawley rats that were subsequently randomized into 3 equal-size groups according to surgical procedure: placement of a vaginal suburethral sling, placement of a vaginal suburethral sling in which the suburethral portion of the sling was immediately cut, and sham surgery without placement of the sling. In a previous study, the leak point pressure measurements were obtained on these rats 6 weeks after surgery. The rats were then killed, the urethrovaginal tissue was harvested (cross-section of the entire urethra and anterior vagina) from 30 animals (10 from each experimental group), and the tissue was stained with hematoxylin-eosin and Masson’s trichrome for histopathologic studies and picrosirius red for collagen fibers. RESULTS As previously published, the median leak point pressures were similarly and significantly increased in the rats in the intact and cut sling groups compared with those in the sham surgery group. The inflammatory mediators and interstitial edema were similarly increased in the intact and cut sling specimens compared with the sham surgery specimens. Under polarized light, picrosirius red-stained specimens from the sham surgery animals appeared to be composed of collagen that predominately birefringed red to yellow (typical of type I collagen). The picrosirius red-stained cut and intact sling specimens appeared to contain collagen fibers that predominately birefringed green (typical of type III collagen). CONCLUSIONS Histologic changes, including inflammation, localized edema, and differential collagen remodeling, might contribute to the preserved anti-incontinence mechanisms of cut or intact polypropylene slings observed clinically.

Postpartum stress urinary incontinence: lessons from animal models

“…No differences in LPP were found between intact slings and slings cut completely at the midurethra during implantation. Further study demonstrated similar inflammatory, edematous and collagenous changes at the site of the intact and cut slings, likely explaining the benefit to continence provided by each [55,129]. These results echo those observed clinically in which sling surgery has proven a successful means of treating SUI in women [130-132].…”

“…Levels of fibrosis in the periurethral area have been assessed by imaging and are correlated with higher LPP and increased continence [55]. Likewise, following simulated childbirth injury, structural disruption of the EUS and PN have been associated with reduced LPP and presumed SUI [44,45].…”

Mild Diabetes Models and Their Maternal-Fetal Repercussions

“…This has led to the suggestion that mitochondria may use lipids as a source of energy for muscular contraction. The increased number of lipid droplets in the diabetic pregnant rats indicates that lipids may be an important energy source for striated muscle [70]. …”

Alterações da matriz extracelular causadas pelo diabetes: o impacto sobre a continência urinária

“…Já o sistema elástico apresenta fibras finas e ramificadas, formando uma rede bastante irregular 10 . O colágeno é o maior componente da MEC; existem 28 tipos de colágeno descritos em todo o corpo, mas os mais abundantes no assoalho pélvico são os tipos I e III 15 . O colágeno tipo I é o maior colágeno de formação fibrilar.…”