Development of an animal model to study meshes used in genital prolapse surgery

[Laparoscopic surgery in the treatment of urogenital prolapse. Current status]

Urogenital prolapse is an emerging problem because of the increasing life expectancy of populations. Nearly 42% of women between 15 and 97 years have a pelvic floor disorder (PFD). On the basis of Medline search, we present the main laparoscopical techniques to treat PFD: Burch, sacrocolpopexy, lateral suspension, uterosacral suspension, paravaginal repair, the benefits of laparoscopic surgery, its success rates and complications, and response to various questions that frequently arise about some techniques: should we perform a hysterectomy? Should we make a paravaginal repair? Should we treat prophylactically a stress urinary incontinence? What type of mesh should we use? What to prefer: staples or sutures? Is the posterior mesh necessary?

Local reaction to the different meshes at the vesicovaginal space in rabbit model

INTRODUCTION AND HYPOTHESIS

This paper aims to study the vesicovaginal space local tissue reaction to type I and II polypropylene mesh in a rabbit model.

METHODS

Different types of meshes were implanted into the rabbit vesicovaginal space. The animals were killed at days 7 and 60, and the initial implant and the neighboring host tissue were removed, including the bladder and vaginal wall. Histopathology and immunohistochemistry (Ki-67 and proliferating cell nuclear antigen) were performed to evaluate the cell proliferation, and the indirect local inflammatory response was described.

RESULTS

One rabbit had erosion at the urinary bladder mucous membrane, which resulted in vesical stone formation in the type I mesh group at day 60. Obvious local tissue reaction was found after the different types of meshes were implanted, and the reaction tapered and disappeared over time. At day 7, the reaction in the type I mesh group was stronger than that in the type II group, while at day 60, the reaction shows no difference.

CONCLUSION

The two types of meshes could induce local tissue reaction, but this was stronger in type I mesh group at day 7 and shows no obvious difference between the two groups at day 60.

Fresh muscle fiber fragments on a scaffold in rats-a new concept in urogynecology?

OBJECTIVE

To investigate if a synthetic, biodegradable scaffold with either autologous in vitro cultured muscle-derived cells or autologous fresh muscle fiber fragments could be used for tissue repair.

STUDY DESIGN

Twenty scaffolds with muscle-derived cells and 20 scaffolds with muscle fiber fragments were implanted subcutaneously on the abdomen of rats, 2 in each rat, and examined after 3 weeks (10 of each preparation) and 8 weeks (10 of each preparation). Immonohistochemistry and histopathology was undertaken for assessment of growth pattern and biocompatibility, respectively.

RESULTS

At 3 weeks, both muscle-derived cells and muscle fiber fragments could be identified. At 8 weeks, the muscle fiber fragments generated fragmented, striated muscle tissue in 6 of 10 explants, whereas the muscle-derived cells and all scaffolds had vanished.

CONCLUSION

Autologous fresh muscle fiber fragments on a biodegradable scaffold seem useful for tissue repair. This study introduces a promising new concept with possible implications for the surgical reconstruction of pelvic organ prolapse.

Inflammatory cytokine and matrix metalloproteinase expression induced by collagen-coated and uncoated polypropylene meshes in a rat model

OBJECTIVE

The objective of the study was to compare the influence of collagen-coated vs uncoated polypropylene meshes on the expression of genes critical for wound healing.

STUDY DESIGN

In 54 rats, abdominal wall defects were created, repaired by polypropylene sutures, and covered by an overlay of coated polypropylene (n = 20), uncoated polypropylene (n = 18), or no mesh (n = 16). Explants were harvested 7 or 90 days after repair and divided for histological, immunohistochemical, and messenger ribonucleic acid (mRNA) analyses. Real-time quantitative polymerase chain reaction arrays were used to profile the expression of 84 genes at the tissue-mesh interface.

RESULTS

One week after implantation, coated mesh elicited a slightly greater inflammatory response and increased mRNA expression of 4 proinflammatory cytokines compared with uncoated mesh. Both materials, however, induced a comparable expression of cytokines and matrix metalloproteinases relative to suture repair 90 days after implantation.

CONCLUSION

Collagen-coated polypropylene mesh induces elevated inflammatory cytokine expression compared with uncoated mesh early in the healing process, but the response to both meshes is similar 90 days after implantation.

Tissue response to a new type of biomaterial implanted subcutaneously in rats

INTRODUCTION AND HYPOTHESIS

A new type of resorbable biomaterial intended for pelvic reconstruction was tested with respect to tissue regeneration and biocompatibility in rats. The biomaterial consisted of methoxypolyethyleneglycol-poly(lactic-co-glycolic acid) (MPEG-PLGA). Implants were pure, enriched with extra-cellular matrix (ECM) or estrogen.

METHODS

Ten implants of each type were tested for 3 and 8 weeks, respectively. Histological assessment of connective tissue organization, inflammation, vascularization, and thickness of regenerated tissue was undertaken.

RESULTS

All implants had a high degree of biocompatibility. ECM-enriched implants had significantly higher inflammatory scores compared to pure implants at 3 weeks. At 8 weeks, neither of the parameters differed significantly. No trace of the implants remained.

CONCLUSIONS

The MPEG-PLGA is highly biocompatible, degrades quickly, and seems inert in the process of tissue regeneration. Thus, it is hardly a candidate per se in reinforcement of pelvic reconstruction, but it could have a future role as carrier for stem cells.