Four-Month Evaluation of PVA-Coated Polypropylene Meshes After Laparoscopic Intraperitoneal Implantation in an Exploratory Porcine Abdominal-Wall Defect Model.

Postoperative intra-abdominal adhesion remains a major limitation of intraperitoneal polypropylene (PP) mesh. We evaluated three poly(vinyl alcohol) (PVA)-coated PP meshes-PVA-PP, rapamycin-loaded liposome-decorated PVA-PP (RPM@LPS/PVA-PP), and the corresponding NaHCO3-containing formulation [RPM@LPS(NaHCO3)/PVA-PP]-in a four-month exploratory laparoscopic Bama miniature-pig study. Two pigs received all four formulations at anatomically separated, randomized abdominal-wall sites, yielding 12 implantation sites in total and three site-level observations per formulation. Gross adhesion, abdominal-wall tissue-mesh mechanics, histology, collagen composition, immunohistochemistry, and multiplex immunofluorescence were assessed. Unmodified PP produced dense visceral attachment at all three implantation sites (mean site-level adhesion score, 4.00), whereas the mean scores for PVA-PP, RPM@LPS/PVA-PP, and RPM@LPS(NaHCO3)/PVA-PP were 0.50, 0.33, and 0.17, respectively. Adhesion area showed the same descriptive ordering. Mean abdominal-wall tissue-mesh lap-shear and peel strengths were also lowest with RPM@LPS(NaHCO3)/PVA-PP (0.0091 MPa and 0.1766 N mm-1, respectively) compared with PP (0.0500 MPa and 0.7823 N mm-1), indicating reduced host-wall integration rather than direct mechanical confirmation of weaker visceral adhesion. Modified interfaces showed less dense fibrous tissue, lower total and Type I collagen, and a higher Type III collagen fraction. The mean Type I/Type III collagen ratio decreased from 15.38 for PP to 2.27 for RPM@LPS(NaHCO3)/PVA-PP. Lower IL-6-, TNF-α-, α-SMA-, CD31-, CD68-, and iNOS-associated signals, together with a higher CD206-positive/CD68-positive area ratio, accompanied these changes. These exploratory two-animal findings show a descriptive association between the use of PVA-coated PP meshes and reduced chronic visceral adhesion, while identifying host-wall integration as a necessary safety consideration.