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Objective Define the impact of prolapse mesh on the biomechanical properties of the vagina by comparing the prototype Gynemesh PS (Ethicon, Somerville, NJ) to 2 new generation lower stiffness meshes, SmartMesh (Coloplast, Minneapolis, MN) and UltraPro (Ethicon). Design A study employing a non-human primate model Setting University of Pittsburgh Population 45 parous rhesus macaques Methods Meshes were implanted via sacrocolpexy after hysterectomy and compared to Sham. Because its stiffness is highly directional UltraPro was implanted in two directions: UltraPro Perpendicular (less stiff) and UltraPro Parallel (more stiff), with the indicated direction referring to the blue orientation lines. The mesh-vaginal complex (MVC) was excised en toto after 3 months. Main Outcome Measures Active mechanical properties were quantified as contractile force generated in the presence of 120 mM KCl. Passive mechanical properties (a tissues ability to resist an applied force) were measured using a multi-axial protocol. Results Vaginal contractility decreased 80% following implantation with the Gynemesh PS (p=0.001), 48% after SmartMesh (p=0.001), 68% after UltraPro parallel (p=0.001) and was highly variable after UltraPro perpendicular (p =0.16). The tissue contribution to the passive mechanical behavior of the MVC was drastically reduced for Gynemesh PS (p=0.003) but not SmartMesh (p=0.9) or UltraPro independent of the direction of implantation (p=0.68 and p=0.66, respectively). Conclusions Deterioration of the mechanical properties of the vagina was highest following implantation with the stiffest mesh, Gynemesh PS. Such a decrease associated with implantation of a device of increased stiffness is consistent with findings from other systems employing prostheses for support.

Objective To evaluate the impact of prolapse meshes on vaginal smooth muscle structure (VaSM) and function, and to evaluate these outcomes in the context of the mechanical and textile properties of the mesh. Design Three months following the implantation of three polypropylene prolapse meshes with distinct textile and mechanical properties, mesh tissue explants were evaluated for smooth muscle contraction, innervation, receptor function, and innervation density. Setting Magee-Womens Research Institute at the University of Pittsburgh. Population Thirty-four parous rhesus macaques of similar age, parity, and pelvic organ prolapse quantification (POP–Q) scores. Methods Macaques were implanted with mesh via sacrocolpopexy. The impact of Gynemesh™ PS (Ethicon; n = 7), Restorelle® (Coloplast; n = 7), UltraPro™ parallel and UltraPro™ perpendicular (Ethicon; n = 6 and 7, respectively) were compared with sham-operated controls (n = 7). Outcomes were analysed by Kruskal–Wallis ANOVA, Mann–Whitney U–tests and multiple regression analysis (P < 0.05). Mean outcome measures Vaginal tissue explants were evaluated for the maximum contractile force generated following muscle, nerve, and receptor stimulation, and for peripheral nerve density. Results Muscle myofibre, nerve, and receptor-mediated contractions were negatively affected by mesh only in the grafted region (P < 0.001, P = 0.002, and P = 0.008, respectively), whereas cholinergic and adrenergic nerve densities were affected in the grafted (P = 0.090 and P = 0.008, respectively) and non-grafted (P = 0.009 and P = 0.005, respectively) regions. The impact varied by mesh property, as mesh stiffness was a significant predictor of the negative affect on muscle function and nerve density (P < 0.001 and P = 0.013, respectively), whereas mesh and weight was a predictor of receptor function (P < 0.001). Conclusions Mesh has an overall negative impact on VaSM, and the effects are a function of mesh properties, most notably, mesh stiffness.

The objective of this study was to define the regional differences in rat vaginal smooth muscle contractility and morphology. We evaluated circumferential segments from the proximal, middle, and distal rat vagina (n ¼ 21) in vitro. Contractile responses to carbachol, phenylephrine, potassium chloride, and electrical field stimulation (EFS) were measured. Immunohistochemical analyses were also performed. The dose-response curves for carbachol-and phenylephrine-dependent contractions were different in the distal (P ¼ .05, P ¼ .04) compared to the proximal/middle regions. Adjusted for region-dependent changes in contractility, the distal vagina generated lower force in response to carbachol and higher force in response to phenylephrine. There was less force with increasing EFS frequency in the distal (P ¼ .03), compared to the proximal/middle regions. Cholinergic versus adrenergic nerves were more frequent in the proximal region (P ¼ .03). In summary, the results indicate that functional and morphological differences in smooth muscle and nerve fibers of the distal versus proximal/middle regions of the vagina exist.

Objectives-The objectives were 1) to determine whether human vaginal fibroblasts are mechanosensitive and 2) to study the impact of mechanical stretch on these cells in the presence and absence of hormones.Methods-Fibroblasts obtained from biopsies of full thickness vagina of 3 women were cyclically biaxially stretched at a magnitude of 8 and 16% for 72 hours with or without 17-β-estradiol plus progesterone. Culture media was collected and total collagenase activity was measured in duplicate using a fluorogenic substrate degradation assay. Data were analyzed at the 0.05 level of significance using Student t-test.Results-Cells remained 90% viable throughout the experiments. Relative to the controls, hormonal treatment alone decreased collagenase activity (P=0.008). In the presence of mechanical stretch and in the absence of hormones, collagenase activity was increased (8% elongation, P=0.04; 16% elongation, P=0.001, respectively). The increase in collagenase activity was linearly correlated with magnitude (P<0.001). In the presence of hormones, the increase in enzyme activity by mechanical stretch was suppressed to baseline control levels (P=0.46). There was no difference in suppression by hormones by magnitude (P=0.48).Conclusions-Vaginal connective tissue fibroblasts are mechanosensitive with increased collagenase activity in the presence of stretch. This degradative behavior is inhibited in the presence of hormones. The data provide a mechanism by which events that induce vaginal stretch may lead to progression of pelvic organ prolapse, particularly, in the absence of hormones. Further studies are needed to determine whether these events lead to tissue with inferior mechanical properties.