Vaginal host response to polycarbonate urethane, an alternative material for the repair of pelvic organ prolapse

Complications following surgical repair of pelvic organ prolapse (POP) with polypropylene mesh (PPM) are common. Recent data attributes complications, in part, to stiffness mismatches between the vagina and PPM. We developed a 3D printed elastomeric membrane (EM) from a softer polymer, polycarbonate urethane (PCU). EMs were manufactured with more material given the low inherent material strength of PCU. We hypothesized that the EMs would be associated with an improved host response as compared to PPM. A secondary goal was to optimize the material distribution (fiber width and device thickness) within EMs, in regards to the host response. EM constructs (2 × 1 cm²) with varied polymer stiffness, fiber width, and device thickness were implanted onto the vagina of New Zealand white rabbits for 12 weeks and compared to similarly sized PPMs. Sham implanted animals served as controls. Mixed effects generalized linear models were used to compare the effect of construct type accounting for differences in independent variables. EMs had an overall superior host response compared to PPM as evidenced by preservation of vaginal smooth muscle morphology (p-values<0.01), decreased total cellular response to construct fibers (p-values<0.001), and a reduced percent of macrophages (p-values<0.02) independent of how the material was distributed. Both PPM and EMs negatively impacted vaginal contractility and glycosaminoglycan (GAG) content relative to Sham (all p-values<0.001) with EMs having less of an impact on GAGs (p-values<0.003). The results suggest that softer PCU EMs made with more material are well tolerated by the vagina and comprises a future material for POP repair devices.

Statement of significance

Prolapse is a debilitating condition in which loss of support to the vagina causes it and the organs supported by it to descend from their normal position in the pelvis. Surgical solutions to rebuild support involves the use of polypropylene mesh which is orders of magnitude stiffer than the vagina. This mismatch results in complications including exposure of the mesh into the vagina and pain. To provide an innovative solution for women, we have developed an elastomeric membrane from a soft polymer that matches the stiffness of the vagina. Here, we show in a rabbit animal model that this device incorporates better into the vagina and is associated with an overall improved host response as compared to polypropylene mesh.