Katrina Knight

Introduction: Implantation of mid-urethral slings (MUSs) is a safe and effective approach for the surgical repair of stress urinary incontinence. However, concerns regarding the deformability of the prototype MUS, mechanical cut Gynecare TVT prompted manufacturers to use techniques like laser cutting, heat-sealing, and the inclusion of an interwoven stabilizing suture to decrease deformation with loading. We hypothesized that a laser cut or heat-sealed MUS would be stiffer but deform less, and experience less permanent elongation as compared to a mechanical cut MUS. Additionally, the inclusion of a stabilizing suture would minimize the loss of porosity.Methods: Uniaxial tensile testing to failure and cyclic loading was performed to analyze the structural properties and permanent elongation, respectively, of commercially available MUSs Gynecare TVT (mechanical cut), Gynecare TVT Exact (laser cut), ArcTV (laser cut, with and without the stabilizing suture), and Desara Blue (heat-sealed). A custom Mathematica code was used to quantify the porosity of the MUSs following sequential uniaxial loading from 0 N to 10 N.Results: Desara Blue was significantly stiffer (p-values < 0.05), elongated less at failure (p = 0.002), and experienced less permanent elongation in response to cyclic loading (p-values = 0.001) relative to Gynecare TVT. Similarly, permanent elongation was significantly less (p-values = 0.004) and the stiffness was higher (p = 0.004) for Gynecare TVT Exact as compared to Gynecare TVT. Very little differences in stiffness and no differences in relative elongation at failure nor permanent elongation were observed between ArcTV (without the interwoven suture) and Gynecare TVT (p-values > 0.05). The porosity of all MUSs significantly decreased with loading (p-values < 0.001); except for ArcTV with the stabilizing suture which showed the least amount of deformation (i.e., percent change in porosity decreasing by only 14%, p < 0.001, at 10 N).Discussion: Overall, heat-sealing decreased deformability at the cost of markedly increasing device stiffness to a point which likely outweighs benefits, and risks increased complications. Laser cutting had different effects on the behavior of TVT Exact and ArcTV suggesting manufacturer technical differences, but overall reduced deformation without a substantial impact on stiffness. An interwoven stabilizing suture minimized the loss of porosity which translates clinically to less deformation and mechanistically to reduced mesh complications.

Pelvic organ prolapse (POP) is the herniation of the pelvic organs into the vaginal space, resulting in the feeling of a bulge and organ dysfunction. Treatment of POP often involves repositioning the organs using a polypropylene mesh, which has recently been found to have relatively high rates of complications. Complications have been shown to be related to stiffness mismatches between the vagina and polypropylene, and unstable knit patterns resulting in mesh deformations with mechanical loading. To overcome these limitations, we have three-dimensional (3D)-printed a porous, monofilament membrane composed of relatively soft polycarbonate-urethane (PCU) with a stable geometry. PCU was chosen for its tunable properties as it is comprised of both hard and soft segments. The bulk mechanical properties of PCU were first characterized by testing dogbone samples, demonstrating the dependence of PCU mechanical properties on its measurement environment and the effect of print pathing. The pore dimensions and load-relative elongation response of the 3D-printed PCU membranes under monotonic tensile loading were then characterized. Finally, a fatigue study was performed on the 3D-printed membrane to evaluate durability, showing a similar fatigue resistance with a commercial synthetic mesh and hence its potential as a replacement.

The application of engineering tools and techniques to studying women’s health, including biomaterials-based approaches, is a research field experiencing robust growth. Biomaterials are natural or synthetic materials used to repair or replace damaged tissues or organs or replicate an organ’s physiological function. However, in addition to in vivo applications, there has been substantial recent interest in biomaterials for in vitro systems. Such artificial tissues and organs are employed in drug discovery, functional cell biological investigations, and basic research that would be ethically impossible to conduct in living women. This Roadmap is a collection of 11 sections written by leading and up-and-coming experts in this field who review and discuss four aspects of biomaterials for women’s health. These include conditions that disproportionately but not exclusively affect women (e.g. breast cancer), conditions unique to female reproductive organs, in both non-pregnant and pregnant states, and sex differences in non-reproductive tissues (e.g. the cardiovascular system). There is a strong need to develop this exciting field, with the potential to materially influence women’s lives worldwide.

Introduction and hypothesis We compared the impact of a mesh manufactured from the soft elastomer polydimethylsiloxane (PDMS) to that of a widely used lightweight polypropylene (PP) mesh. To achieve a similar overall device stiffness between meshes, the PDMS mesh was made with more material and therefore was heavier and less porous. We hypothesized that the soft polymer PDMS mesh, despite having more material, would have a similar impact on the vagina as the PP mesh. Methods PDMS and PP meshes were implanted onto the vaginas of 20 rabbits via colpopexy. Ten rabbits served as sham. At 12 weeks, mesh-vagina complexes were explanted and assessed for contractile function, histomorphology, total collagen, and glycosaminoglycan content. Outcome measures were compared using one-way ANOVA and Kruskal-Wallis testing with appropriate post-hoc testing. Results Relative to sham, vaginal contractility was reduced following the implantation of PP (p = 0.035) but not the softer PDMS (p = 0.495). PP had an overall greater negative impact on total collagen and glycosaminoglycan content, decreasing by 53% (p < 0.001) and 54% (p < 0.001) compared to reductions of 35% (p = 0.004 and p < 0.001) with PDMS. However, there were no significant differences in the contractility, collagen fiber thickness, total collagen, and glycosaminoglycan content between the two meshes. Conclusions Despite having a substantially higher weight, PDMS had a similar impact on the vagina compared to a low-weight PP mesh, implicating soft polymers as potential alternatives to PP. The notion that heavyweight meshes are associated with a worse host response is not applicable when comparing across materials.