Biomaterials for pelvic floor reconstructive surgery: how can we do better?

An in vitro pilot study investigating placenta-derived mesenchymal stem cell coating on polypropylene mesh materials

INTRODUCTION AND HYPOTHESIS

Polypropylene meshes (PM) used in pelvic organ prolapse surgery are being withdrawn from the market. Although concerns about the usage of PMs in stress incontinence surgery have been raised, it is still one of the best methods of curing stress urinary incontinence. With advancements in stem cell-based therapies, especially mesenchymal stem cells (MSCs), it is believed that coating the synthetic meshes with MSCs may minimize excessive tissue reactions ultimately leading to clinical problems such as pain, erosion or extrusion of the implanted material. In our study we tried to show the possibility of coating the PM with placenta-derived MSCs.

METHODS

Mesenchymal stem cells obtained from six placentas were isolated, cultured, and identified. MSCs were then soaked in either fibronectin or collagen prior to co-culturing with strips of PMs. One group is used as a control, and hence was not pretreated before co-culturing. Specimens were fixed and stained with both Gram and hematoxylin and eosin and marked with Vybran Dil and DAPI. All preparations were examined under a light microscope. The IMAGEJ program was utilized to determine the surface area of meshes coated with MSCs.

RESULTS

We clearly showed that PMs can be coated successfully with placenta-derived MSCs. The percentage of the coated area is significantly increased when meshes were pretreated with fibronectin or collagen (p<0.0001).

CONCLUSIONS

Placenta-derived MSCs can successfully coat PMs. The immunomodulatory properties of MSCs, which may be of great advantage in preventing the side effects of meshes, should be tested by in vivo and hopefully human studies before clinical applications.

Accelerated in vitro oxidative degradation testing of polypropylene surgical mesh

Polypropylene (PP) surgical mesh had reasonable success in repair of hernia and treatment of stress urinary incontinence (SUI); however, their use for the repair of pelvic organ prolapse (POP) resulted in highly variable results with lifelong complications in some patients. One of several factors that could be associated with mesh-related POP complications is changes in the properties of the implanted surgical mesh due to oxidative degradation of PP in vivo. Currently, there are no standardized in vitro bench testing methods available for assessing the susceptibility to oxidative degradation and estimating long-term in vivo stability of surgical mesh. In this work, we adapted a previously reported automated reactive accelerated aging (aRAA) system, which uses elevated temperatures and high concentrations of hydrogen peroxide (H2 O2 ), for accelerated bench-top oxidative degradation testing of PP surgical mesh. Since H2 O2 is highly unstable at elevated temperatures and for prolonged periods, the aRAA system involves a feedback loop based on electrochemical detection methods to maintain consistent H2 O2 concentration in test solutions. Four PP mesh samples with varying mesh knit designs, filament diameter, weight, and % porosity, were selected for testing using aRAA up to 4 weeks and characterized using thermal analysis, Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM). Additionally, the oxidation index (OI) values were calculated based on the FTIR-ATR spectra to estimate the oxidative degradation and oxidation reaction kinetics of PP surgical mesh. The OI values and surface damage in the form of surface flaking, peeling, and formation of transverse cracks increased with aRAA aging time. The aRAA test method introduced here could be used to standardize the assessment of long-term stability of surgical mesh and may also be adopted for accelerated oxidative degradation testing of other polymer-based medical devices.

Supramolecular Fibrous Hydrogel Augmentation of Uterosacral Ligament Suspension for Treatment of Pelvic Organ Prolapse

Uterosacral ligament suspension (USLS) is a common surgical treatment for pelvic organ prolapse (POP). However, the relatively high failure rate of up to 40% underscores a strong clinical need for complementary treatment strategies, such as biomaterial augmentation. Herein, the first hydrogel biomaterial augmentation of USLS in a recently established rat model is described using an injectable fibrous hydrogel composite. Supramolecularly-assembled hyaluronic acid (HA) hydrogel nanofibers encapsulated in a matrix metalloproteinase (MMP)-degradable HA hydrogel create an injectable scaffold showing excellent biocompatibility and hemocompatibility. The hydrogel can be successfully delivered and localized to the suture sites of the USLS procedure, where it gradually degrades over six weeks. In situ mechanical testing 24 weeks post-operative in the multiparous USLS rat model shows the ultimate load (load at failure) to be 1.70 ± 0.36 N for the intact uterosacral ligament (USL), 0.89 ± 0.28 N for the USLS repair, and 1.37 ± 0.31 N for the USLS + hydrogel (USLS+H) repair (n = 8). These results indicate that the hydrogel composite significantly improves load required for tissue failure compared to the standard USLS, even after the hydrogel degrades, and that this hydrogel-based approach can potentially reduce the high failure rate associated with USLS procedures.

Polypropylene Pelvic Mesh: What Went Wrong and What Will Be of the Future?

Background: Polypropylene (PP) pelvic mesh is a synthetic mesh made of PP polymer used to treat pelvic organ prolapse (POP). Its use has become highly controversial due to reports of serious complications. This research critically reviews the current management options for POP and PP mesh as a viable clinical application for the treatment of POP. The safety and suitability of PP material were rigorously studied and critically evaluated, with consideration to the mechanical and chemical properties of PP. We proposed the ideal properties of the ‘perfect’ synthetic pelvic mesh with emerging advanced materials. Methods: We performed a literature review using PubMed/Medline, Embase, Cochrane Library (Wiley) databases, and ClinicalTrials.gov databases, including the relevant keywords: pelvic organ prolapse (POP), polypropylene mesh, synthetic mesh, and mesh complications. Results: The results of this review found that although PP is nontoxic, its physical properties demonstrate a significant mismatch between its viscoelastic properties compared to the surrounding tissue, which is a likely cause of complications. In addition, a lack of integration of PP mesh into surrounding tissue over longer periods of follow up is another risk factor for irreversible complications. Conclusions: PP mesh has caused a rise in reports of complications involving chronic pain and mesh exposure. This is due to the mechanical and physicochemical properties of PP mesh. As a result, PP mesh for the treatment of POP has been banned in multiple countries, currently with no alternative available. We propose the development of a pelvic mesh using advanced materials including emerging graphene-based nanocomposite materials.

Transvaginal Mesh-related Complications and the Potential Role of Bacterial Colonization: An Exploratory Observational Study

STUDY OBJECTIVE

This study aimed to investigate the potential role of transvaginal mesh bacterial colonization in the development of mesh-related complications (MRCs).

DESIGN

An observational and exploratory study.

SETTING

Tertiary referral center (Amsterdam UMC, location AMC, Amsterdam, The Netherlands). PATIëNTS: 49 patients indicated for mesh removal and 20 women of whom vaginal tissue was retrieved during prolapse surgery as a reference cohort.

INTERVENTIONS

collection of mesh-tissue complex (patient cohort) or vaginal tissue (reference cohort) MEASUREMENTS AND MAIN RESULTS: Homogenized samples were used for quantitative microbiological culture. Inflammation and fibrosis were semiquantitatively histologically scored; Gram staining and fluorescence in situ hybridization were used to detect bacteria and bacterial biofilms. Of the 49 patients, 44 samples (90%) were culture positive, with a higher diversity of species and more Gram-negative bacteria and polymicrobial cultures in the MRC cohort than the reference cohort, with mostly staphylococci, streptococci, Actinomyces spp., Cutibacterium acnes, and Escherichia coli. Patients with clinical signs of infection or exposure had the highest bacterial counts. Histology demonstrated moderate to severe inflammation in most samples. Gram staining showed bacteria in 57% of culture-positive samples, and in selected samples, fluorescence in situ hybridization illustrated a polymicrobial biofilm.

CONCLUSION

In this study, we observed distinct differences in bacterial numbers and species between patients with MRCs and a reference cohort. Bacteria were observed at the mesh-tissue interface in a biofilm. These results strongly support the potential role of bacterial mesh colonization in the development of MRCs.

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Absorbable Electrospun Poly-4-hydroxybutyrate Scaffolds as a Potential Solution for Pelvic Organ Prolapse Surgery

Women with pelvic organ prolapse (POP) have bothersome complaints that significantly affect their quality of life. While native tissue repair is associated with high recurrence rates, polypropylene knitted implants have caused specific implant-related adverse events that have detrimental, often irreversible, effects. We hypothesize that surgical outcome can be improved with a tissue-engineered solution using an absorbable implant that mimics the natural extracellular matrix (ECM) structure, releases estrogen, and activates collagen metabolism by fibroblasts as the main regulators of wound healing. To this aim, we produced electrospun poly-4-hydroxybutyrate (P4HB) scaffolds and biofunctionalized them with estradiol (E2). The cell-implant interactions relevant for POP repair were assessed by seeding primary POP vaginal fibroblasts isolated from patients on electrospun P4HB scaffolds with 1%, 2%, or 5% E2 and without E2. To test our hypothesis on whether ECM mimicking structures should improve regeneration, electrospun P4HB was compared to knitted P4HB implants. We evaluated vaginal fibroblast proliferation, ECM deposition, and metabolism by quantification of collagen, elastin, and matrix metalloproteinases and by gene expression analysis for 28 days. We established effective E2 drug loading with a steady release over time. Significantly higher cell proliferation, collagen-, and elastin deposition were observed on electrospun P4HB scaffolds as compared to knitted P4HB. For this study, physical properties of the scaffolds were more determinant on the cell response than the release of E2. These results indicate that making these electrospun P4HB scaffolds E2-releasing appears to be technically feasible. In addition, electrospun P4HB scaffolds promote the cellular response of vaginal fibroblasts and further studies are merited to assess if their use results in improved surgical outcomes in case of POP repair.

Tissue-engineered repair material for pelvic floor dysfunction

Pelvic floor dysfunction (PFD) is a highly prevalent urogynecology disorder affecting many women worldwide, with symptoms including pelvic organ prolapse (POP), stress urinary incontinence (SUI), fecal incontinence, and overactive bladder syndrome (OAB). At present, the clinical treatments of PFD are still conservative and symptom-based, including non-surgical treatment and surgery. Surgical repair is an effective and durable treatment for PFD, and synthetic and biological materials can be used to enforce or reinforce the diseased tissue. However, synthetic materials such as polypropylene patches caused a series of complications such as mesh erosion, exposure, pain, and inflammation. The poor mechanical properties and high degradation speed of the biomaterial meshes resulted in poor anatomical reduction effect and limitation to clinical application. Therefore, the current treatment options are suboptimal. Recently, tissue-engineered repair material (TERM) has been applied to repair PFD and could markedly improve the prognosis of POP and SUI repair surgery in animal models. We review the directions and progression of TERM in POP and SUI repair. Adipose-derived stem cells (ADSCs) and endometrial mesenchymal stem cells (eMSCs) appear to be suitable cell types for scaffold seeding and clinical implantation. The multidisciplinary therapy approach to tissue engineering is a promising direction for tissue repair. More and longer follow-up studies are needed before determining cell types and materials for PFD repair.

The impact of bacterial contamination on the host response towards fully absorbable poly-4-hydroxybutyrate and nonabsorbable polypropylene pelvic floor implants

Polypropylene (PP) implants for the vaginal surgical correction of pelvic organ prolapse (POP) are known for adverse events, like vaginal or visceral exposures. It is hypothesized that this is a result of a prolonged inflammatory response. One of the triggering factors of prolonged inflammation might be bacterial contamination. A possible solution might lie in an absorbable biomaterial, which provides initial mechanical support while being gradually replaced by the host tissue.

With this study we aimed to compare the host response, in a subcutaneous mouse implant infection model, to delayed absorbable poly-4-hydroxybutyrate (P4HB) and a latest generation PP implant. By comparing non-infected to Staphylococcus aureus infected mice, we assessed how bacterial contamination affects the host response and its role in the development of complications. Further, we included sham surgery as a control, mimicking the wound response in native tissue repair.

Despite the higher surface area of the P4HB implants, the clearance of infection was similarly delayed in the presence of a P4HB or PP implant, as compared to sham. Further, the host response towards P4HB and PP was quite comparable, yet collagen deposition was significantly increased around infected P4HB implants at early time points. Adverse event rates were similar, though implant exposures were only seen in infected mice and more often with PP (11.1%) than P4HB implants (5.6%). Infected mice overall had significantly higher levels of infiltration of inflammatory cells and lower levels of vascularization and collagen deposition compared to non-infected mice. Thus, for both P4HB and PP, bacterial contamination negatively affected mesh integration by increased inflammation and an increased adverse event rate. Altogether, our results from this subcutaneous mouse implant infection study suggest that P4HB could be a promising degradable alternative to PP, warranting further research to study its potential as a new surgical solution for women with POP.

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Absorbable poly-4-hydroxybutyrate (P4HB) is studied as a novel pelvic floor implant.

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Comparable host response to P4HB and polypropylene in a subcutaneous mouse implant infection model.

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Implant exposures exclusively occurred upon Staphylococcus aureus infection.

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Exposures occurred less with P4HB (5.6%) compared to polypropylene (11.1%).

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S. aureus infection increased inflammation and deranged the host response.

Melt-extrusion 3D printing of resorbable levofloxacin-loaded meshes: Emerging strategy for urogynaecological applications

Current surgical strategies for the treatment of pelvic floor dysfunctions involve the placement of a polypropylene mesh into the pelvic cavity. However, polypropylene meshes have proven to have inadequate mechanical properties and have been associated to the arising of severe complications, such as infections. Furthermore, currently employed manufacturing strategies are unable to produce compliant and customisable devices. In this work, polycaprolactone has been used to produce resorbable levofloxacin-loaded meshes in two different designs (90° and 45°) via melt-extrusion 3D printing. Drug-loaded meshes were produced using a levofloxacin concentration of 0.5% w/w. Drug loaded meshes were successfully produced with highly reproducible mechanical and physico-chemical properties. Tensile test results showed that drug-loaded 45° meshes possessed a mechanical behaviour close to that of the vaginal tissue (E ≃ 8.32 ± 1.85 MPa), even after 4 weeks of accelerated degradation. Meshes released 80% of the loaded levofloxacin in the first 3 days and were capable of producing an inhibitory effect against S. Aureus and E. coli bacterial strains with an inhibition zone equal to 12.8 ± 0.45 mm and 15.8 ± 0.45 mm respectively. Thus, the strategy adopted in this work holds great promise for the manufacturing of custom-made surgical meshes with antibacterial properties.

Evaluating tissue-engineered repair material for pelvic floor dysfunction: a comparison of in vivo response to meshes implanted in rats

INTRODUCTION AND HYPOTHESIS

Achieving better anatomic restoration and decreasing the associated complications are necessary for material repair of pelvic floor dysfunction (PFD). This study was aimed to investigate host response to tissue-engineered repair material (TERM) in rat models by comparing different materials and study the changes in biomechanical properties over time.

METHODS

TERM was constructed by seeding adipose-derived stem cells (ADSCs) on electrospun poly(L-lactide)-trimethylene carbonate-glycolide (PLTG) terpolymers. The TERM, PLTG, porcine small intestine submucosa mesh (SIS), and polypropylene (PP) (n = 6 / group per time point) were implanted in rats for 7, 30, 60, and 90 days. Hematoxylin-eosin and Masson's trichrome staining were used to assess the host response, and mechanical testing was used to evaluate the changes in biomechanical properties.

RESULTS

In vivo imaging showed that the ADSCs were confined to the abdominal wall and did not migrate to other organs or tissues. The TERM was encapsulated by a thicker layer of connective tissue and was associated with less reduced inflammatory scores compared with PLTG and PP over time. The vascularization of the TERM was greater than that with PP and PLTG over time (p < 0.05) and was greater than that with SIS on day 90. The ultimate tensile strain and Young's modulus of the PP group showed the greatest increases, and the TERM group followed on day 90.

CONCLUSIONS

This TERM achieved better host integration in rat models and better biomechanical properties, and it may be an alternative material for PFD.

Efficacy and safety of pelvic organ prolapse surgery with porcine small intestinal submucosa graft implantation

OBJECTIVE

The ideal implant material for the surgical repair of pelvic organ prolapse in women is yet to be found. This retrospective study aims to evaluate a porcine small intestinal submucosa (SIS) graft (Surgisis™).

STUDY DESIGN

We reviewed the medical records of women that were operated upon for pelvic organ prolapse using implantation of SIS graft and we examined the short-term complications and recurrence rates.

RESULTS

A total of 155 surgical procedures were reviewed. SIS graft was placed in the anterior, posterior and middle compartments in 93 (60%), 71 (45.8%) and 13 (8.4%) cases, respectively. At three-month follow-up, 22.6% of anterior graft repairs displayed anatomical recurrence (POP-Q stage ≥ 2), compared to 4.8% of posterior and none of the middle compartment graft repairs. During the three postoperative months, 56% of the women were recorded with complications, mostly urinary retention (19%) and pain (12%). The incidence of grade III complications was 5.3%. Persistent complications at three months were observed in 28% of all cases. Logistic regression analysis showed that previous prolapse surgery at the same compartment was a significant predictor for recurrence of prolapse after SIS graft application, whereas lower age, smoking and longer duration of surgery were significant predictors for the development of complications. Younger women had higher risk of developing pain postoperatively.

CONCLUSION

Pain and urinary tract symptoms hold a central position in the complications profile of SIS graft-augmented prolapse surgery. The relatively high recurrence rates do not suggest a clear benefit from SIS graft use.

Development of a cellulose-based prosthetic mesh for pelvic organ prolapse treatment: In vivo long-term evaluation in an ewe vagina model

The use of vaginal surgical mesh to treat pelvic organ prolapse (POP) has been associated with high rates of mesh-related complications. In the present study, we prepared new kinds of meshes based on bacterial cellulose (BC) and collagen-coated BC (BCCOL) using a laser cutting method and perforation technique. The mechanical properties of pre-implanted BC meshes, including breaking strength, suture strength and rigidity, were equal to or exceeded those of available clinically used polypropylene meshes. An in vitro cellular assay revealed that BCCOL meshes exhibited enhanced biocompatibility by increasing collagen secretion and cell adhesion. Both BC and BCCOL meshes only caused weak inflammation and were surrounded by newly formed connective tissue composed of type I collagen after implantation in a rabbit subcutaneous model for one week, demonstrating that the novel mesh is fully biocompatible and can integrate into surrounding tissues. Furthermore, a long-term (ninety days) ewe vaginal implantation model was used to evaluate foreign body reactions and suitability of BC and BCCOL meshes as vaginal meshes. The results showed that the tissue surrounding the BC meshes returned to its original physiology as muscle tissue, indicating the excellent integration of BC meshes into the surrounding tissues without triggering severe local inflammatory response post-implantation. The collagen coating appeared to induce a chronic inflammatory response due to glutaraldehyde remnants. The present exploratory research demonstrated that the developed BC mesh might be a suitable candidate for treating POP.

Animal experimental research assessing urogynecologic surgical mesh implants: Outcome measures describing the host response, a systematic review and meta-analysis

Aim

Before the introduction of new biomaterials for prolapse surgery, animal studies on the host response are required. Unfortunately, large variation in study design hampers obtaining an overview of the safety and efficacy, and translation to clinical practice. Our aim is to systematically review the literature on all outcome measures describing the host response in animal studies assessing the biocompatibility of urogynecologic surgical mesh implants for prolapse surgery. Furthermore, by meta‐analysis, we aim to assess the effect of implantation and compare this to control animals receiving sham surgery or native tissue repair.

Methods

We performed a systematic search from inception to August 2020. Since this is an explorative study we included original, controlled, and noncontrolled animal studies describing any host response to the implant. Quantitative outcome measures reported ≥10 times in ≥2 articles were eligible for meta‐analysis.

Results

Fifty articles were included in the qualitative synthesis and 36 articles were eligible for meta‐analysis. In total, 154 outcome measures were defined and classified into (1) histomorphology, (2) biomechanics and, (3) macroscopic morphology. Animals with vaginal implants demonstrated significantly increased M1 and M2 macrophages, MMP‐2, neovascularization, TNF‐α, and stiffness, and lower vaginal contractility compared to control animals.

Conclusion

The host response significantly differs in animals after vaginal mesh implantation compared to control animals, both pro‐ and anti‐inflammatory. However, we observed a paucity in the uniformity of reported outcomes. For future animal studies, we propose the development of a core outcome set, which ideally predicts the host response in women.

Laparoscopic latero-abdominal colposuspension: Description of the technique, advantages and preliminary results

INTRODUCTION

There are currently various fixation or suspension techniques for pelvic organ prolapse (POP) surgery. Laparoscopic colposacropexy is considered the gold standard. We present the surgical steps of the laparoscopic latero-abdominal colposuspension (LACS) technique and the preliminary results obtained.

MATERIAL AND METHODS

Patients with anterior and/or apical compartment symptomatic POP undergoing LACS are included. The Baden-Walker scale, the Overactive Bladder Questionnaire-Short Form (OAB-q SF), the Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire (PISQ-12) and the Patient Global Impression of Improvement (PGI-I) scale were used to assess the degree of prolapse, urinary filling and sexual symptoms and the level of satisfaction before and after surgery, respectively. Conventional laparoscopic material and a polyvinylidene fluoride (PVDF) mesh were used.

RESULTS

Eighteen patients were included with a minimum follow-up time of 6months. The mean surgical time was 70.3±23.8min. Anatomic correction of prolapse was seen in all cases. Only one recurrence was detected. High levels of patient satisfaction were achieved.

CONCLUSION

LACS allowed the anatomical reconstruction of the pelvic floor and proved to be a minimally invasive, fast, effective, safe and reproducible technique. More series are needed to evaluate its role against laparoscopic colposacropexy.

Next-generation surgical meshes for drug delivery and tissue engineering applications: materials, design and emerging manufacturing technologies

Abstract

Surgical meshes have been employed in the management of a variety of pathological conditions including hernia, pelvic floor dysfunctions, periodontal guided bone regeneration, wound healing and more recently for breast plastic surgery after mastectomy. These common pathologies affect a wide portion of the worldwide population; therefore, an effective and enhanced treatment is crucial to ameliorate patients’ living conditions both from medical and aesthetic points of view. At present, non-absorbable synthetic polymers are the most widely used class of biomaterials for the manufacturing of mesh implants for hernia, pelvic floor dysfunctions and guided bone regeneration, with polypropylene and poly tetrafluoroethylene being the most common. Biological prostheses, such as surgical grafts, have been employed mainly for breast plastic surgery and wound healing applications. Despite the advantages of mesh implants to the treatment of these conditions, there are still many drawbacks, mainly related to the arising of a huge number of post-operative complications, among which infections are the most common. Developing a mesh that could appropriately integrate with the native tissue, promote its healing and constructive remodelling, is the key aim of ongoing research in the area of surgical mesh implants. To this end, the adoption of new biomaterials including absorbable and natural polymers, the use of drugs and advanced manufacturing technologies, such as 3D printing and electrospinning, are under investigation to address the previously mentioned challenges and improve the outcomes of future clinical practice. The aim of this work is to review the key advantages and disadvantages related to the use of surgical meshes, the main issues characterizing each clinical procedure and the future directions in terms of both novel manufacturing technologies and latest regulatory considerations.

Graphic abstract

In Vitro Bacterial Adhesion and Biofilm Formation on Fully Absorbable Poly-4-hydroxybutyrate and Nonabsorbable Polypropylene Pelvic Floor Implants

Knitted polypropylene (PP) implants for the correction of pelvic organ prolapse have been associated with complications such as vaginal exposure, infection, and pain. Since certain complications may be linked to bacterial contamination and persistent inflammation, there is a rationale to develop a biocompatible implant that is less prone to bacterial adhesion and biofilm formation. Delayed absorbable materials could meet these requirements and poly-4-hydroxybutyrate (P4HB) might be such a new material for future pelvic floor implants. We studied in vitro bacterial adhesion and biofilm formation on P4HB in comparison to PP. We investigated the influence of both polymers using flat films and compared P4HB and PP implants with different knitting designs. P4HB flat films were demonstrated to be hydrophilic with significantly less Staphylococcus aureus and Escherichia coli cultured from P4HB films than from hydrophobic PP films after 24 h of incubation. On the implants, a higher number of E. coli were cultured after 1 h of incubation from the knitted P4HB implant with the highest density and smallest pore size, compared to other P4HB and PP implants. No differences were observed between the implants for E. coli at later time points or for S. aureus incubation. These results show that in flat films, the polymer influences biofilm formation, demonstrated by a reduced biofilm formation on P4HB compared with PP flat films. In addition, the knitting design may affect bacterial adhesion. Despite certain design and material characteristics that give the knitted P4HB implants a higher surface area, this did not result in more bacterial adhesion and biofilm formation overall. Collectively, these results warrant further (pre)clinical investigations of P4HB pelvic floor implants.

Biologic Grafts for Use in Pelvic Organ Prolapse Surgery: a Contemporary Review

PURPOSE OF REVIEW

Pelvic organ prolapse (POP) is a common condition and there is a plethora of surgical techniques available to address this problem. We present a review of biologic grafts, including the latest literature to help guide a surgeon's choice on the type of biologic materials to augment repairs.

RECENT FINDINGS

Since the 2019 Food and Drug Administration (FDA) ban on mesh, including xenograft, there is a sparsity of biologic graft products available for POP repairs. This has led to a significant decrease in surgical application. Surgeons must be familiar with the biochemical properties, processing, and clinical application of biologic grafts prior to use. They should also be familiar with alternative operative techniques that utilize autografts, although there is limited outcome data on these techniques. With heightened awareness of mesh and its complications, biologic grafts have made a resurgence. Surgeons must be well versed on their available options. Current literature is limited, and studies have not demonstrated superiority of biologic graft over native tissue repairs for prolapse. Nevertheless, there is a role for these types of biologic graft material in specific patient populations. Future studies are warranted.

A novel antibacterial biomaterial mesh coated by chitosan and tigecycline for pelvic floor repair and its biological performance

The biomaterials composed of mammalian extracellular matrix (ECM) have a great potential in pelvic floor tissue repair and functional reconstruction. However, bacterial infection does cause great damage to the repair function of biomaterials which is the major problem in clinical utilization. Therefore, the development of biological materials with antimicrobial effect is of great clinical significance for pelvic floor repair. Chitosan/tigecycline (CS/TGC) antibacterial biofilm was prepared by coating CS/TGC nanoparticles on mammalian-derived ECM. Infrared spectroscopy, scanning electron microscopy, bacteriostasis circle assay and static dialysis methods were used to characterize the membrane. MTS assay kit and DAPI fluorescence staining were used to evaluate cytotoxicity and cell adhesion. The biocompatibility was assessed by subabdominal implantation model in goats. Subcutaneous antimicrobial test in rabbit back was used to evaluate the antimicrobial and repairing effects on the infected wounds in vivo. Infrared spectroscopy showed that the composite coating had been successfully modified. The antibacterial membrane retained the main structure of ECM multilayer fibers. In vitro release of biomaterials showed sustained release and stability. In vivo studies showed that the antibacterial biological membrane had low cytotoxicity, fast degradation, good compatibility, anti-infection and excellent repair ability.

Emerging Nano/Micro-Structured Degradable Polymeric Meshes for Pelvic Floor Reconstruction

Pelvic organ prolapse (POP) is a hidden women's health disorder that impacts 1 in 4 women across all age groups. Surgical intervention has been the only treatment option, often involving non-degradable meshes, with variable results. However, recent reports have highlighted the adverse effects of meshes in the long term, which involve unacceptable rates of erosion, chronic infection and severe pain related to mesh shrinkage. Therefore, there is an urgent unmet need to fabricate of new class of biocompatible meshes for the treatment of POP. This review focuses on the causes for the downfall of commercial meshes, and discusses the use of emerging technologies such as electrospinning and 3D printing to design new meshes. Furthermore, we discuss the impact and advantage of nano-/microstructured alternative meshes over commercial meshes with respect to their tissue integration performance. Considering the key challenges of current meshes, we discuss the potential of cell-based tissue engineering strategies to augment the new class of meshes to improve biocompatibility and immunomodulation. Finally, this review highlights the future direction in designing the new class of mesh to overcome the hurdles of foreign body rejection faced by the traditional meshes, in order to have safe and effective treatment for women in the long term.

Titanized polypropylene mesh in laparoscopic sacral colpopexy

INTRODUCTION

This study investigated perioperative and mid-term clinical outcomes after laparoscopic sacrocolpopexy (LSCP) with light titanium-coated polypropylene (TCP) mesh in a large group of patients affected by International Continence Society stage II-IV pelvic organ prolapse (POP).

METHODS

This multicenter retrospective study included 217 patients treated with LSCP using TCP mesh. We aimed to (1) analyze the intra- and postoperative complication rates according to the ICS/IUGA Complication Classification Code guidelines, (2) evaluate the anatomical results and (3) assess postoperative patient satisfaction with the Patient Global Impression Improvement questionnaire. Nonparametric Wilcoxon signed-rank tests, χ2 test and Fisher's exact test were used where appropriate.

RESULTS

The intraoperative complications were two (0.9%) cases of hemorrhage, two (0.9%) cases of incidental cystotomy and four (1.8%) cases of incidental colpotomy. During the postoperative follow-up, we recorded mesh exposure in 3 (1.4%) out of 217 patients. These 3 patients were from a group of 22 women who underwent vaginal opening during surgery, while in the remaining 195 patients without incidental colpotomy, no mesh exposure was observed (13.6% vs. 0.0%, p < 0.001). No failure of the apical compartment was observed, while 3 (1.4%) out of 217 patients experienced isolated anterior recurrence, and 1 (0.4%) patient had isolated posterior recurrence. All patients reported PGI-I scores ≥ 3, and 209 patients (96.3%) had a PGI-I score ≥ 2.

CONCLUSIONS

The use of light TCP mesh is safe and effective during LSCP for POP repair from both an anatomical and a functional point of view, posing a very low postoperative mesh-related complication risk.

The in vivo biocompatibility of titanized polypropylene lightweight mesh is superior to that of conventional polypropylene mesh

OBJECTIVE

To evaluate the histological response to and changes in the biomechanical properties of titanized polypropylene lightweight mesh and conventional polypropylene mesh at 1 and 12 weeks following implantation in the sheep vagina.

METHODS

We compared a titanized polypropylene lightweight mesh (TiLOOP Mesh) to a conventional polypropylene mesh (Gynemesh PS) in a sheep vagina model. Explants were harvested after 1 and 12 weeks (n = 6/mesh type/time point) for histological observation. After 12 weeks, mesh-tissue complex specimens were biomechanically assessed by a uniaxial tension system.

RESULTS

One week after implantation, there was no significant difference in the inflammatory response between the two groups. Twelve weeks after implantation, the TiLOOP light mesh elicited a lower inflammatory response than was observed for the Gynemesh PS (1.44 ± 0.61 vs 2.05 ± 0.80, P = .015). Twelve weeks after implantation, the collagen I/III ratio was lower in the TiLOOP light mesh group than in the Gynemesh PS group (9.41 ± 5.06 vs 15.21 ± 8.21, P = .019). The messenger RNA expression levels of the inflammatory factors interleukin 10 and tumor necrosis factor α were lower in the TiLOOP Mesh group than in the Gynemesh PS group at both 1 and 12 weeks (P < .05). There were no significant differences in any of the evaluated biomechanical characteristics between the two meshes (P > .05).

CONCLUSION

Although the titanized polypropylene lightweight mesh induces slightly less tissue reactivity and has better in vivo biocompatibility, further studies should be conducted including the complications and the success rate of pelvic organ prolapse in patients before recommending it in pelvic floor reconstruction.

Methacrylic Acid Copolymer Coating Enhances Constructive Remodeling of Polypropylene Mesh by Increasing the Vascular Response

This study reports that a methacrylic acid (MAA)-based copolymer coating generates constructive remodeling of polypropylene (PP) surgical mesh in a subcutaneous model. This coating is non-bioresorbable and follows the architecture of the mesh without impeding connective tissue integration. Following implantation, the tissue response is biased toward vascularization instead of fibrosis. The vessel density around the MAA mesh is double that of the uncoated mesh two weeks after implantation. This initial vasculature regresses after two weeks while mature vessels remain, suggesting an enhanced healing response. Concurrently, the MAA coating alters the foreign body response to the mesh. Fewer infiltrating cells, macrophages, and foreign body giant cells are found at the tissue-material interface three weeks after implantation. The coating also dampens inflammation, with lower expression levels of pro-inflammatory and fibrogenic signals (e.g., Tgf-β1, Tnf-α, and Il1-β) and similar expression levels of anti-inflammatory cytokines (e.g., Il10 and Il6) compared to the uncoated mesh. Contrary to other coatings that aim to mitigate the foreign body response to PP mesh, a MAA coating does not require the addition of any biological agents to have an effect, making the coated mesh an attractive candidate for soft tissue repair.

Managing female pelvic floor disorders: a medical device review and appraisal

Pelvic floor disorders (PFDs) will affect most women during their lifetime. Sequelae such as pelvic organ prolapse, stress urinary incontinence, chronic pain and dyspareunia significantly impact overall quality of life. Interventions to manage or eliminate symptoms from PFDs aim to restore support of the pelvic floor. Pessaries have been used to mechanically counteract PFDs for thousands of years, but do not offer a cure. By contrast, surgically implanted grafts or mesh offer patients a more permanent resolution but have been in wide use within the pelvis for less than 30 years. In this perspective review, we provide an overview of the main theories underpinning PFD pathogenesis and the animal models used to investigate it. We highlight the clinical outcomes of mesh and grafts before exploring studies performed to elucidate tissue level effects and bioengineering considerations. Considering recent turmoil surrounding transvaginal mesh, the role of pessaries, an impermanent method, is examined as a means to address patients with PFDs.

Gene expression in stress urinary incontinence: a systematic review

INTRODUCTION

A contribution of genetic factors to the development of stress urinary incontinence (SUI) is broadly acknowledged. This study aimed to: (1) provide insight into the genetic pathogenesis of SUI by gathering and synthesizing the available data from studies evaluating differential gene expression in SUI patients and (2) identify possible novel therapeutic targets and leads.

METHODS

A systematic literature search was conducted through September 2017 for the concepts of genetics and SUI. Gene networking connections and gene-set functional analyses of the identified genes as differentially expressed in SUI were performed using GeneMANIA software.

RESULTS

Of 3019 studies, 4 were included in the final analysis. A total of 13 genes were identified as being differentially expressed in SUI patients. Eleven genes were overexpressed: skin-derived antileukoproteinase (SKALP/elafin), collagen type XVII alpha 1 chain (COL17A1), plakophilin 1 (PKP1), keratin 16 (KRT16), decorin (DCN), biglycan (BGN), protein bicaudal D homolog 2 (BICD2), growth factor receptor-bound protein 2 (GRB2), signal transducer and activator of transcription 3 (STAT3), apolipoprotein E (APOE), and Golgi SNAP receptor complex member 1 (GOSR1), while two genes were underexpressed: fibromodulin (FMOD) and glucocerebrosidase (GBA). GeneMANIA revealed that these genes are involved in intermediate filament cytoskeleton and extracellular matrix organization.

CONCLUSION

Many genes are involved in the pathogenesis of SUI. Furthermore, whole-genome studies are warranted to identify these genetic connections. This study lays the groundwork for future research and the development of novel therapies and SUI biomarkers in clinical practice.

Medium-term outcome of laparoscopic sacrocolpopexy using polivinylidene fluoride as compared to a hybrid polyglecaprone and polypropylene mesh: A matched control study

AIM

To compare 2-year outcomes of laparoscopic sacrocolpopexy (LSCP) either with polyvinylidene fluoride (PVDF) or hybrid polypropylene containing a resorbable polyglecaprone (PP+ PG) mesh.

MATERIALS AND METHODS

Retrospective audit on 105 consecutive patients undergoing LSCP a with PVDF-mesh (DynaMesh, FEG Textiltechniken), matched by prolapse stage and cervicopexy or vault suspension to 105 controls undergoing LSCP with a hybrid PP + PG-mesh (Ultrapro, Ethicon). Patients are part of an ongoing prospective study. The primary outcome measure was the Patient Global Impression of Change score (PGIC), the coprimary variable was failure rate at the vault (≤1 cm). Other outcomes were intraoperative and postoperative complications within 3 months categorized by the Clavien-Dindo classification, reinterventions, graft-related complications (GRCs) and functional outcomes. All assessments were performed by an independent assessor. Data are reported as median (interquartile range) number and percent as appropriate, the Mann-Whitney U, χ² , or Fisher exact were used for comparison.

RESULTS

Patient satisfaction in the PVDF group, as measured with the PGIC, was high (90.9% PGIC, ≥4) as well as was the anatomical success (97.3%) at a follow-up of 26 months. These outcomes were comparable to those of PP + PG-patients (84.8% PGIC, ≥4; 94.9% anatomical success). There were five patients (2.4%) with Dindo-III or higher complications and three patients had GRCs (1.5%), without differences between mesh type. Level-II posterior defects (Bp ≥ -1) were less likely in PVDF patients (34.1% vs 50% for PP + PG-patients; P = .003). Women in the PVDF group also were less bothered by prolapse (7.5% vs 26.4%; P = .001), yet they complained more of constipation (15.0% vs 9.0%; P = .01).

CONCLUSION

There were no differences in patient satisfaction and anatomical outcomes after LSCP either with PVDF or PP + PG mesh.

The challenge of stress incontinence and pelvic organ prolapse: revisiting biologic mesh materials

PURPOSE OF REVIEW

The present article reviews the history of mesh-related complications and regulations in SUI and POP repair settings, clinical outcomes associated with the use of biologic and synthetic mesh materials, and novel approaches using modified mesh materials.

RECENT FINDINGS

Treatment of pelvic floor disorders, such as stress urinary incontinence (SUI) and pelvic organ prolapse (POP) commonly involves implantation of synthetic surgical mesh materials like polypropylene. Many synthetic mesh materials, however, are associated with a foreign body response upon implantation, which is characterized by fibrotic encapsulation. Complications, including erosion, infections, bleeding, and chronic pain, have led to warnings by regulatory agencies and the recall of several mesh products. To mitigate such complications, biologic mesh materials have been proposed as alternatives for SUI and POP repair.

SUMMARY

Clinical outcomes of surgical repair of POP/SUI are similar between biologic and synthetic meshes, but biologic meshes have a lower incidence of adverse effects. Several strategies for modifying or functionalizing biological and synthetic meshes have shown promising results in preclinical studies.

Experimental study of a new original mesh developed for pelvic floor reconstructive surgery

INTRODUCTION AND HYPOTHESIS

Most synthetic meshes used in transvaginal surgery are made of polypropylene, which has a stable performance, but does not easily degrade in vivo. However, mesh-related complications are difficult to address and have raised serious concerns. A new biomaterial mesh with good tissue integration and few mesh-related complications is needed. To evaluate the effect of a new bacterial cellulose (BC) mesh on pelvic floor reconstruction following implantation in the vagina of sheep after 1 and 12 weeks.

METHODS

The meshes were implanted in the submucosa of the posterior vagina wall of sheep. At 1 and 12 weeks after surgery, mesh-tissue complex (MTC) specimens were harvested for histological studies and biomechanical evaluation. At 12 weeks after surgery, MTC specimens were biomechanically assessed by a uniaxial tension "pulley system".

RESULTS

The BC mesh elicited a higher inflammatory response than Gynemesh™PS at both 1 and 12 weeks after implantation. Twelve weeks after implantation, the BC mesh resulted in less fibrosis than Gynemesh™PS. Compared with the Gynemesh™PS group, the BC mesh group had increased mRNA expression of MMP-1, MMP-2, and MMP-9 (P < 0.05), but decreased expression of the anti-inflammatory factor IL-4 (P < 0.05). Twelve weeks after implantation, the ultimate load and maximum elongation percentage of the BC mesh were significantly lower than those of Gynemesh™PS.

CONCLUSIONS

The BC mesh could not be a promising biomaterial for pelvic floor reconstructive surgery unless the production process and parameters were improved.

In vivo biocompatibility and time-dependent changes in mechanical properties of woven collagen meshes: A comparison to xenograft and synthetic mid-urethral sling materials

Meshes woven from highly aligned collagen threads crosslinked using either genipin or 1-ethyl-3-(3-dimethylaminopropyl) carboiimide and N-hydroxy succinimide (EDC/NHS) were implanted in a subcutaneous rat model to evaluate their biocompatibility (at 2 weeks, 2 months, and 5 months), mechanical properties (at baseline, 2 months, and 5 months) and ultimately their suitability for use as mid-urethral slings (MUS) for management of stress urinary incontinence. Porcine dermal (Xenmatrix) and monofilament polypropylene (Prolene) meshes were also implanted to provide comparison to clinically used materials. Quantitative histological scoring showed tissue integration in Xenmatrix was almost absent, while the open network of woven collagen and Prolene meshes allowed for cellular and tissue integration. However, strength and stiffness of genipin-crosslinked collagen (GCC), Prolene, and Xenmatrix meshes were not significantly different from those of native rectus fascia and vaginal tissues of animals at 5 months. EDC/NHS-crosslinked collagen (ECC) meshes were degraded so extensively at five months that samples could only be used for histological staining. Picrosirius red and Masson's trichrome staining revealed that integrated tissue within GCC meshes was more aligned (p = 0.02) and appeared more concentrated than ECC meshes at 5 months. Furthermore, immunohistochemical staining showed that GCC meshes attracted a greater number of cells expressing markers for M2 macrophages, those associated with regeneration, than ECC meshes (p = 0.01 for CD206+ cells, p = 0.001 CD163+ cells) at 5 months. As such, GCC meshes hold promise as a new MUS biomaterial based on favorable induction of fibrous tissue resulting in mechanical stiffness matching that of native tissue. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 479-489, 2019.

Endometrial Mesenchymal Stem/Stromal Cells Modulate the Macrophage Response to Implanted Polyamide/Gelatin Composite Mesh in Immunocompromised and Immunocompetent Mice

The immunomodulatory properties of human endometrial mesenchymal stem cells (eMSC) have not been well characterised. Initial studies showed that eMSC modulated the chronic inflammatory response to a non-degradable polyamide/gelatin mesh in a xenogeneic rat skin wound repair model, but the mechanism remains unclear. In this study, we investigated the immunomodulatory effect of eMSC on the macrophage response to polyamide/gelatin composite mesh in an abdominal subcutaneous wound repair model in C57BL6 immunocompetent and NSG (NOD-Scid-IL2Rgamma^null) immunocompromised mice to determine whether responses differed in the absence of an adaptive immune system and NK cells. mCherry lentivirus-labelled eMSC persisted longer in NSG mice, inducing longer term paracrine effects. Inclusion of eMSC in the mesh reduced inflammatory cytokine (Il-1β, Tnfα) secretion, and in C57BL6 mice reduced CCR7⁺ M1 macrophages surrounding the mesh on day 3 and increased M2 macrophage marker mRNA (Arg1, Mrc1, Il10) expression at days 3 and 7. In NSG mice, these effects were delayed and only observed at days 7 and 30 in comparison with controls implanted with mesh alone. These results show that the differences in the immune status in the two animals directly affect the survival of xenogeneic eMSC which leads to differences in the short-term and long-term macrophage responses to implanted meshes.

Scaffolds for Pelvic Floor Prolapse: Logical Pathways

Pelvic organ prolapse (POP) has borrowed principles of treatment from hernia repair and in the last two decades we saw reinforcement materials to treat POP with good outcomes in terms of anatomy but with alarming complication rates. Polypropylene meshes to specifically treat POP have been withdrawn from market by manufactures and a blank space was left to be filled with new materials. Macroporous monofilament meshes are ideal candidates and electrospinning emerged as a reliable method capable of delivering production reproducibility and customization. In this review, we point out some pathways that seem logical to be followed but have been only researched in last couple of years.

Comparing different tissue-engineered repair materials for the treatment of pelvic organ prolapse and urinary incontinence: which material is better?

INTRODUCTION AND HYPOTHESIS

Synthetic non-absorbable meshes are widely used to augment surgical repair of pelvic organ prolapse (POP) and stress urinary incontinence (SUI), but these meshes are associated with serious complications. This study compares the attachment and extracellular matrix (ECM) production of adipose-derived stem cells (ADSCs) on different biodegradable nanomaterials to develop tissue engineered repair materials.

METHODS

Rat ADSCs were isolated and cultured on electrospun poly-L-lactic acid (PLA) and electrospun poly(L-lactide)-trimethylene carbonate-gycolide (PLTG) terpolymers for 1 and 2 weeks. Samples were tested for cell proliferation (cell counting kit-8), microstructure, and morphology (scanning electron microscopy), production of ECM components (immunostaining for collagen I, collagen III, and elastin) and biomechanical properties (uniaxial tensile methods).

RESULTS

The ADSCs showed good attachment and proliferation on both PLA and PLTG scaffolds. The production of collagen I and collagen III on both scaffolds was greater at 14 days than at 7 days and was greater on PLTG scaffolds than on PLA scaffolds, but these differences were not significant. The addition of ADSCs onto scaffolds led to a significant increase in the biomechanical properties of both PLA and PLTG scaffolds compared with unseeded scaffolds.

CONCLUSION

These data support the use of both PLA and PLTG as tissue-engineered repair materials for POP or SUI.

In vivo response to polypropylene following implantation in animal models: a review of biocompatibility

INTRODUCTION AND HYPOTHESIS

Polypropylene is a material that is commonly used to treat pelvic floor conditions such as pelvic organ prolapse (POP) and stress urinary incontinence (SUI). Owing to the nature of complications experienced by some patients implanted with either incontinence or prolapse meshes, the biocompatibility of polypropylene has recently been questioned. This literature review considers the in vivo response to polypropylene following implantation in animal models. The specific areas explored in this review are material selection, impact of anatomical location, and the structure, weight and size of polypropylene mesh types.

METHODS

All relevant abstracts from original articles investigating the host response of mesh in vivo were reviewed. Papers were obtained and categorised into various mesh material types: polypropylene, polypropylene composites, and other synthetic and biologically derived mesh.

RESULTS

Polypropylene mesh fared well in comparison with other material types in terms of host response. It was found that a lightweight, large-pore mesh is the most appropriate structure.

CONCLUSION

The evidence reviewed shows that polypropylene evokes a less inflammatory or similar host response when compared with other materials used in mesh devices.

Developing Repair Materials for Stress Urinary Incontinence to Withstand Dynamic Distension

BACKGROUND

Polypropylene mesh used as a mid-urethral sling is associated with severe clinical complications in a significant minority of patients. Current in vitro mechanical testing shows that polypropylene responds inadequately to mechanical distension and is also poor at supporting cell proliferation.

AIMS AND OBJECTIVES

Our objective therefore is to produce materials with more appropriate mechanical properties for use as a sling material but which can also support cell integration.

METHODS

Scaffolds of two polyurethanes (PU), poly-L-lactic acid (PLA) and co-polymers of the two were produced by electrospinning. Mechanical properties of materials were assessed and compared to polypropylene. The interaction of adipose derived stem cells (ADSC) with the scaffolds was also assessed. Uniaxial tensiometry of scaffolds was performed before and after seven days of cyclical distension. Cell penetration (using DAPI and a fluorescent red cell tracker dye), viability (AlamarBlue assay) and total collagen production (Sirius red assay) were measured for ADSC cultured on scaffolds.

RESULTS

Polypropylene was stronger than polyurethanes and PLA. However, polypropylene mesh deformed plastically after 7 days of sustained cyclical distention, while polyurethanes maintained their elasticity. Scaffolds of PU containing PLA were weaker and stiffer than PU or polypropylene but were significantly better than PU scaffolds alone at supporting ADSC.

CONCLUSIONS

Therefore, prolonged mechanical distension in vitro causes polypropylene to fail. Materials with more appropriate mechanical properties for use as sling materials can be produced using PU. Combining PLA with PU greatly improves interaction of cells with this material.

Transforming surgery through biomaterial template technology

Templates inserted into surgical wounds strongly influence the healing responses in humans. The science of these templates, in the form of extracellular matrix biomaterials, is rapidly evolving and improving as the natural interactions with the body become better understood.

Preclinical animal study and human clinical trial data of co-electrospun poly(L-lactide-co-caprolactone) and fibrinogen mesh for anterior pelvic floor reconstruction

Synthetic and biological materials are commonly used for pelvic floor reconstruction. In this study, host tissue response and biomechanical properties of mesh fabricated from co-electrospun poly(l-lactide-co-caprolactone) (PLCL) and fibrinogen (Fg) were compared with those of polypropylene mesh (PPM) in a canine abdominal defect model. Macroscopic, microscopic, histological, and biomechanical evaluations were performed over a 24-week period. The results showed that PLCL/Fg mesh had similar host tissue responses but better initial vascularization and graft site tissue organization than PPM. The efficacy of the PLCL/Fg mesh was further examined in human pelvic floor reconstruction. Operation time, intraoperative blood loss, and pelvic organ prolapse quantification during 6-month follow-up were compared for patients receiving PLCL/Fg mesh versus PPM. According to the pelvic organ prolapse quantification scores, the anterior vaginal wall 3 cm proximal to the hymen point (Aa point), most distal edge of the cervix or vaginal cuff scar point (C point), and posterior fornix point (D point) showed significant improvement (P<0.01) at 1, 3, and 6 months for both groups compared with preoperatively. At 6 months, improvements at the Aa point in the PLCL/Fg group were significantly more (P<0.005) than the PPM group, indicating that, while both materials improve the patient symptoms, PLCL/Fg mesh resulted in more obvious improvement.