There is an urgent need to develop better materials to provide anatomical support to the pelvic floor without compromising its function. Our aim was to assess outcomes after simulated vaginal prolapse repair in a sheep model using three different materials: (1) ultra-lightweight polypropylene (PP) non-degradable textile (Restorelle) mesh, (2) electrospun biodegradable ureidopyrimidinone-polycarbonate (UPy-PC), and (3) electrospun non-degradable polyurethane (PU) mesh in comparison with simulated native tissue repair (NTR). These implants may reduce implant-related complications and avoid vaginal function loss. A controlled trial was performed involving 48 ewes that underwent NTR or mesh repair with PP, UPy-PC, or PU meshes (n=12/group). Explants were examined 60 and 180 d (six per group) post-implantation. Posterior rectovaginal dissection, NTR, or mesh repair. Implant-related complications, vaginal contractility, compliance, and host response were assessed. Power calculation and analysis of variance testing were used to enable comparison between the four groups. There were no visible implant-related complications. None of the implants compromised vaginal wall contractility, and passive biomechanical properties were similar to those after NTR. Shrinkage over the surgery area was around 35% for NTR and all mesh-augmented repairs. All materials were integrated well with similar connective tissue composition, vascularization, and innervation. The inflammatory response was mild with electrospun implants, inducing both more macrophages yet with relatively more type 2 macrophages present at an early stage than the PP mesh. Three very different materials were all well tolerated in the sheep vagina. Biomechanical findings were similar for all mesh-augmented repair and NTR. Constructs induced slightly different mid-term inflammatory profiles. Product innovation is needed to reduce implant-related complications. We tested two novel implants, electrospun and an ultra-lightweight polypropylene textile mesh, in a physiologically relevant model for vaginal surgery. All gave encouraging outcomes.

Background: Pelvic organ prolapse affects half of vaginally parous women. Several animal models are used to study its pathophysiology and treatment. Sheep are interesting because they develop spontaneously prolapse with similar risk factors as women and can be used for vaginal surgery. This study describes ovine pelvis anatomy and compares it to women's pelvis to provide anatomical tools for translational researchers. Methods: MRI, pelvic dissections, and histology were used for detailed macro- and microscopic analysis of relevant anatomical structures in 6 nulliparous ewes. Results: Although sheep are quadrupeds, the gross and microscopic anatomies are similar to the female pelvis. Principal differences are the shape and its orientation, the absence of the sacrospinous ligament and the internal obturator. The levator ani (except for the puborectalis) and the coccygeus muscle are present, yet the latter is more developed - coinciding with the tail. The dimensions and morphology of the ovine vagina is comparable. The retropubic and the rectovaginal space are accessible transvaginally. There is a wide expression of estrogen receptors with low or absent immunoreactivity in the urethral epithelium, bladder, anus and internal anal sphincter. Conclusion: The ovine pelvic floor has many anatomical and ultrastructural similarities to the female pelvic floor.