Impact of Repeat Dosing and Mesh Exposure Chronicity on Exosome-Induced Vaginal Tissue Regeneration in a Porcine Mesh Exposure Model.

Abstract

<h4>Objective</h4>The aim of the study was to compare vaginal wound healing after exosome injection in a porcine mesh exposure model with (1) single versus multiple dose regimens and (2) acute versus subacute exposure.<h4>Methods</h4>Six 80-kg Yorkshire-crossed swine each had 2 polypropylene meshes implanted to create the vaginal mesh exposure model. Animals were divided into 3 groups based on number and timing of exosome injection: (1) single purified exosome product (PEP) injection (acute-single), (2) weekly PEP injections (acute-weekly, 4 total injections), and (3) delayed single injection (subacute-single). Acute and subacute injections occurred 1 and 8 weeks after mesh implantation, respectively. EdU, a thymidine analog, was given twice weekly after the first injection to track tissue regeneration. Euthanasia and tissue analysis occurred 4 weeks after the first injection. ImageJ was used to quantify epithelial thickness, cellular proliferation, and capillary density. Statistical analysis was performed using analysis of variance and post hoc Tukey test.<h4>Results</h4>Acute-single PEP injection tissues mirrored pilot study results, validating replication of protocol. Within the acute groups, weekly dosing resulted in 1.5× higher epithelial thickness (nonsignificant), 1.8× higher epithelial proliferation (P < 0.05), and 1.5× higher regenerated capillary density (P < 0.05) compared with single injection. Regarding chronicity of the exposure, the subacute group showed 1.7× higher epithelial proliferation (nonsignificant) and similar capillary density and epithelial thickness as compared with the acute group.<h4>Conclusions</h4>Exosome redosing resulted in significantly greater epithelial proliferation with significantly higher regenerated capillary density, leading to a trend toward thicker epithelium. Subacute exposure exhibited similar regeneration to acute exposure despite a delayed injection timeline. These results contribute to a growing body of preclinical research demonstrating utility of exosomes in pelvic floor disorders.