New Rat Model Mimicking Sacrocolpopexy for POP Treatment and Biomaterials Testing via Unilateral Presacral Suspension

Introduction and hypothesis: Pelvic organ prolapse (POP) impacts women's health and quality of life. Post-surgery complications can be severe. This study uses rat models to replicate sacrocolpopexy and test materials for pelvic support, verifying the 4-week postoperative mortality rate, the mechanical properties of the mesh tissue, and the collagen content.

Methods: Twenty-one 12-week-old female Wistar rats were used. Eighteen rats were subjected to POP induction by cervical suction and constant traction. One week after prolapse modeling, 18 prolapsed rats underwent unilateral presacral suspension (UPS) surgery with polycaprolactone (PCL) scaffolds, decellularized porcine small intestinal submucosa (SIS) scaffolds, or polypropylene (PP) meshes (n = 6 each). UPS rats were compared with normal rats (n = 3). After 4 weeks, conditions and mortality were recorded. The rats were then euthanized for biomechanical testing and collagen analysis. Ultimate load (N) was defined as the highest load before the failure of the target sample.

Results: The UPS procedure requires 42.9 ± 4.5 min with no complications or deaths over 4 weeks. SIS was the stiffest mesh (14.53 ± 0.86 N), followed by PP (8.43 ± 0.40 N), and PCL was the least stiff (0.66 ± 0.05 N). After 4 weeks, the ultimate load of the PCL complex increased to 1.71 ± 0.41 N (p = 0.0120), but showed no significant difference from parametrial fascia (1.25 ± 0.85 N) and uterosacral ligament (0.66 ± 0.41 N). The ultimate load of the SIS complex decreased to 5.99 ± 0.37 N, still higher than native tissue. The PP complex's ultimate load (10.02 ± 1.80 N) showed no significant difference from PP alone. The collagen ratio of the PCL complex (48.11 ± 9.88%) was closest to that of the uterosacral ligament (36.66 ± 11.64%), whereas SIS and PP complexes had significantly higher collagen ratios than USL.

Conclusions: Unilateral presacral suspension mimics classical surgery for human POP in rats. First, this procedure can investigate the mechanical properties of pelvic floor tissues at the cellular level after correcting POP. Second, it can be used to validate new materials for the surgical treatment of POP, including but not limited to foreign body reactions with surrounding tissues, absorption time, etc. Third, it can be used to study the biological mechanisms of mesh exposure.