Animal Experiment On Vaginal Reconstruction And Repair Of Pelvic Organs Prolapse With A Heterognous Acellular Tissue Matrix Material

Objective To investigate the effect on using a heterognous acellular tissue matrix material in vaginal reconstruction and pelvic organ prolapse repair in the animal model.Material&Methods In11Chinese experimental miniature pigs, total vaginal excision were performed and vaginal reconstruction with heterognous acellular tissue matrix material (both porcine dermal and bovine pericardium) followed. The control group was two of normal vaginal specimens resected. After1,2,4,6,8weeks, the animal were sacrificed, the vaginal length was reevaluated and the neovaginas were prepared for the histologic evaluation. The formalin-fixed vaginas specimens were dehydrated in graded ethanol solution and embedded in paraffin,4μm sections were cut mounted on precoated slides, and stained for H&E, VG, immunohistochemistry stain were performed with pancytokeratins AE1/AE3to identify for epithelial cell layers, with smooth muscle-special a-actin antibodies for smooth muscle fibers, and with Laminin antibodies to prove if the neovagina can create basement membrane components.13Chinese experimental miniature pigs which were divided into3groups, were implanted with3kinds of different material containing heterognous ATM (both porcine dermal and bovine pericardium) and polypropylene (PP) mesh in the vagina. Grafts were harvested after2,4,6,8,12weeks in ATM groups and after2,4,8weeks in PP group, to evaluate the host inflammatory response and degree of tissue incorporation within the grafts. Static mechanical properties of grafts were determined with an instruments RGM-3010mechanical analyzer Before the implantation.Result1、The Chinese experimental miniature pig model of vaginal reconstruction surgery was performed successfully based on the prior experience, and further improvement in urinary passage management was tried. The neovaginas were regenerated well. Vaginal apex stenosis and shrinkage were not observed.2、In the PS group, similar to the prior investigation using homogeneous ATM mesh, We observed epithelialization of the graft after2weeks. Light microscopy inspection showed that the epithelium was flat,2-3layers, which was mildly infiltrated by leucocytes and erythrocytes. Within4-6weeks, epithelialization was continued in the neovaginal canal. The epithelium was thicker and multi-layer. There were few leucocytes and erythrocytes infiltrated. After8weeks, the neovagina was hardly differentiated from the native one at either macro or micro appearance. Epithelial cell layers were identified with broadly reacting monoclonal anti-pancytokeratins AE1/AE3since2weeks after surgery, which was accordant to the H&E stain. 3、Within lweek, in VG stain, remained ATM can be observed and was contained with elastic fibers and collangen fibers. After2weeks, a few smooth muscle cells can be observed with VG stain and immunohistochemistry stain positive monoclonal a-smooth muscle actin antibodies. Smooth muscle fascicle was appeared after8weeks which was consistent with the prior investigation from Dr. Zhou Huimei. The immunohistochemistry stain positive result of monoclonal Laminin antibodies indicated that the neovaginas can create basement membrane components, in order to prove the integrality of the neovaginas. Because of the thick and tenacious texture of bovine pericardium ATM material, It can not paste with the vaginal wall tightly, so that we considered it was not feasible for BS to be developed as the dermal scaffold for vaginal reconstruction.4、Tensile strength test for the3kinds of material before implanted into the vagina showed PS, BS and the PP mesh result in similar tensile resistance. But PS provided insufficient tenacity at the beginning.5、The Chinese experimental miniature pig model of vaginal mesh implanted was performed successfully. Mesh prolapse and erosion were not observed.6、Degradation can be observed from both macro and micro appearance in ATM mesh (both porcine dermal and bovine pericardium), but PP mesh was neither absorbed nor degraded. The inflammatory response which PP mesh induced was similar to the ATM mesh, and with good host tissue incorporation within the grafts, host tissue incorporated into vaginal PP grafts consists of new collagen, fibroblasts, blood vessels, and elastic fibers.Conclusion1、This study improves the animal model of vaginal reconstruction and firstly reports to use heterognous ATM material to create a vagina implantation model in Chinese experimental miniature pigs. The animal model is stable and reliable. It is proved that is the perfect animal for gynecological study.2、It is the first report to use heterognous acellular tisuue matrix as vaginal reconstruction material and the porcine ATM mesh received good result. The neovagina length is enough. Neither vaginal apex nor shrinkage is obversed. Native cell infiltrate the ATM and epithelium and smooth muscle are regenerated, which are consistent with the prior investigation using homogeneous ATM mesh. Nevertheless, long-term studies and clinical evaluation should be done in the future.3、The BS ATM is not fit for vaginal reconstruction Because of the thick and tenacious texture. 4、Tensile strength test for the3kinds of material before implanted into the vagina showed PS,BS and the PP mesh result in similar baseline tensile resistance, But PS provided insufficient tenacity.5、The ATM mesh may undergo long-term degradation by a foreign body response (both porcine dermal and bovine pericardium), which may lead to compromised biomechanical properties of grafts and unacceptable surgical failure rates. It suggest that ATM grafts are likely inferior to lightweight PP meshes for pelvic organ prolapse procedures.