Porcine Mesh Research Articles

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

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. 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. 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. 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.

Exosome-Induced Vaginal Tissue Regeneration in a Porcine Mesh Exposure Model.

The purpose of this study was to explore the utility of an injectable purified exosome product derived from human apheresis blood to (1) augment surgical closure of vaginal mesh exposures, and (2) serve as a stand-alone therapy for vaginal mesh exposure. Sixteen polypropylene meshes (1×1-3×3 cm) were implanted in the vaginas of 7 Yorkshire-crossed pigs by urogynecologic surgeons (day 0). On day 7, group 1 underwent surgical intervention via vaginal tissue suture reclosure with (n=2 pigs, n=4 meshes) or without (n=2 pigs, n=4 meshes) exosome injection; group 2 underwent medical intervention with an exosome injection (n=3, n=8 meshes). One animal in group 2 was given oral 2'-deoxy-5-ethynyluridine to track cellular regeneration. Euthansia occurred at 5 weeks. Mesh exposures treated with surgical closure alone experienced reexposure of the mesh. Exosome treatment with or without surgical closure resulted in partial to full mesh exposure resolution up to 3×3 cm. Exosome-treated tissues had significantly thicker regenerated epithelial tissue (208 μm exosomes-only and 217 μm surgery+exosomes, versus 80 μm for surgery-only; P < 0.05); evaluation of 2'-deoxy-5-ethynyluridine confirmed de novo regeneration throughout the epithelium and underlying tissues. Capillary density was significantly higher in the surgery+exosomes group (P = 0.03). Surgery-only tissues had a higher inflammatory and fibrosis response as compared with exosome-treated tissues. In this pilot study, exosome treatment augmented healing in the setting of vaginal mesh exposure, reducing the incidence of mesh reexposure after suture closure and decreasing the area of mesh exposure through de novo tissue regeneration after exosome injection only. Further study of varied local tissue conditions and mesh configurations is warranted.

Risk-adjusted adverse outcomes in complex abdominal wall hernia repair with biologic mesh: A case series of 140 patients

IntroductionBiologic mesh is preferred for repair of complex abdominal wall hernias (CAWHs) in patients at high risk of wound infection. We aimed to identify predictors of adverse outcomes after complex abdominal wall hernia repair (CAWR) using biologic mesh with different placement techniques and under different surgical settings. MethodsA retrospective case series study was conducted on all patients who underwent CAWR with biologic mesh between 2010 and 2015 at a tertiary medical center.Results: the study population included 140 patients with a mean age of 54 ± 14 years and a median follow up period 8.8 months. Mesh size ranged from 50 to 1225 cm2. Ninety percent of patients had undergone previous surgery. Type of surgery was classified as elective in 50.7%, urgent in 24.3% and emergent in 25.0% and a porcine mesh was implanted in 82.9%. The most common mesh placement technique was underlay (70.7%), followed by onlay (16.4%) and bridge (12.9%). Complications included wound complications (30.7%), reoperation (25.9%), hernia recurrence (20.7%), and mesh removal (10.0%). Thirty-two patients (23.0%) were admitted to the ICU and the mean hospital length of stay was 10.8 ± 17.5 days. Age-sex adjusted predictors of recurrence were COPD (OR 4.2; 95%CI 1.003–17.867) and urgent surgery (OR 10.5; 95%CI 1.856–59.469), whereas for reoperation, mesh size (OR 6.8; 95%CI 1.344–34.495) and urgent surgery (OR 5.2; 95%CI 1.353–19.723) were the predictors. ConclusionsUsing biologic mesh, one-quarter and one-fifth of CAWR patients are complicated with reoperation or recurrence, respectively. The operation settings and comorbidity may play a role in these outcomes regardless of the mesh placement techniques.

Hospital wide porcine mesh conversion results in cost savings with equivalent clinical outcomes

BackgroundA variety of biologic mesh is available for ventral hernia repair. Despite widely variable costs, there is no data comparing cost of material to clinical outcome. MethodsBiologic mesh product change was examined. A prospective survey was done to determine appropriate biologic mesh utilization, followed by a retrospective chart review of those treated from Sept. 2012 to Aug. 2013 with Strattice™ and from Sept. 2013 to Aug. 2014 with Permacol™. Outcome variables included complications associated with each material, repair success, and cost difference over the two periods. Results28 patients received Strattice™ and 41 Permacol™. There was no statistical difference in patient factors, hernia characteristics, length of stay, readmission rates or surgical site infections at 30 days. The charges were significantly higher for Strattice™ with the median cost $8940 compared to $1600 for Permacol™ (p < 0.001). Permacol™ use resulted in a savings if $181,320. ConclusionsPermacol™ use resulted in similar clinical outcomes with significant cost savings when compared to Strattice™. Biologic mesh choice should be driven by a combination of clinical outcomes and product cost.

Development of a novel murine model for treatment of infected mesh scenarios.

Indications regarding hernia repair after removal of previously infected prostheses remain unclear. Patients may receive staged primary repair or single-stage reconstructions, neither of which may be ideal. Although animal models have simulated contamination by direct inoculation of implants with bacteria, there remains a paucity of literature, which simulates a field following mesh infection and removal. We aimed to develop a murine model to mimic this complex scenario to allow for further testing of various implants. Thirty-six female CL57BL/6J mice underwent implantation of a 0.7×0.7cm polyester mesh in the dorsal subcutaneous position. Wounds were closed and inoculated with 100µL containing 1×104 CFU of GFP-labeled MSSA. After 2weeks, the infected mesh was removed and the cavity was copiously irrigated with saline. Mice were split into four groups: with three groups receiving new polyester, polypropylene, and porcine mesh and remaining as non-mesh controls. Mice were survived for another 2weeks and underwent necropsy. Gross infection was evaluated at 2 and 4weeks. Tissue homogenization and direct plating to recover GFP MSSA was completed at 4weeks. At 2weeks, all mice were noted to have gross mesh infection. One animal died due to overwhelming infection and wound breakdown. At 4weeks, 5/6 (83%) control mice who did not have a second mesh implantation had full clearance of their wounds. In contrast, 9/10 (90%) mice with re-implantation of polypropylene were noted to have pus and recovery of GFP MSSA on plating. This was also observed in 100% of mice with polyester and porcine mesh. Our novel murine model demonstrates that mesh re-implantation after infected mesh removal results in infection of the newly placed prosthesis, regardless of the material characteristic or type. This model lays foundation for development and investigation of implants for treatment strategies following infected mesh removal.

Bioprosthetic mesh reinforcement during temporary stoma closure decreases the rate of incisional hernia: A blinded, case-matched study in 94 patients with rectal cancer

This case-matched study aimed to assess the feasibility and the potential benefits of placement of a prophylactic bioprosthetic collagen porcine mesh during closure of the temporary ileostomy after total mesorectal excision (TME) for rectal cancer. From September 2012 to March 2013, 30 consecutive patients underwent placement of a retromuscular bioprosthetic mesh in the abdominal wall during closure of a diverting ileostomy after sphincter-saving laparoscopic TME for rectal cancer (mesh group). These 30 patients were matched individually to all identical patients who underwent a closure of the ileostomy without mesh after laparoscopic TME extracted from our prospective database (control group). The matching process was performed according to sex, age, body mass index, medically treated diabetes mellitus, neoadjuvant radiotherapy, and the delay between TME and closure of the ileostomy. The primary endpoint was stoma site incisional hernia, assessed in a blinded fashion by CT 1 year later. Mesh placement was feasible in all mesh group patients. There was no postoperative mortality. Overall postoperative morbidity rates were similar between mesh and control groups (n = 5 [17%] vs n = 7 [11%], respectively; P = .512). On the 1-year CT, incisional hernia at the site of stomal closure was less in the mesh group (n = 1) compared with the control group (n = 12; P = .043). Reoperation for incisional hernia at the site of stomal closure was performed in 8 patients (13%) in the control group, whereas no patient from the mesh group required repair of the hernia (P = .052). Placement of a bioprosthetic collagen porcine mesh during closure of the temporary ileostomy after laparoscopic TME for rectal cancer seems to decrease the chance of hernia formation at the stoma site, at least at the 1-year follow-up.

PWE-386 Development of perineal hernias following abdominoperineal excision for low rectal cancer

Introduction Previously, perineal herniation following abdominoperineal excision (APE) has been considered a rare complication affecting Method Retrospective data on patients who underwent APE between May 2006 and October 2014 in a single UK institution were collected. Analysis of Magnetic Resonance Imaging (MRI) and Computerised Tomography (CT) scans determined pelvic cavity dimensions and the presence of perineal herniation. Perineal hernias were defined as a defect containing bowel, uterus, bladder, vagina or omentum dropping below the pubococcygeal line. Consequently asymptomatic perineal hernias were included in this data. Perineal defects resolving naturally over time were not considered to be a hernia. Pelvic floor descent was measured from the pubococcygeal line to the lowest point of the descended material or matter. Data for gender and treatment with chemoradiotherapy (CRT) were extracted from patient notes. Data were tested for normality and appropriate t-tests used. Results Post-operative data were available for 63/73 patients, mean age 67 years (range 26–85), of which 67% were male. First postoperative scans presented 17/63 (27%) patients with a perineal hernia. Most recent scans showed 23/63 (37%) patients with a perineal hernia. No significant difference was found between post-operative pelvic outlet size and presence of a perineal hernia (9.8 v 10.3, P Conclusion Our data suggest that the size of the pelvic outlet and gender could be less important than previously thought in development of a perineal hernia. It could be suggested that patients at risk of perineal herniation present early after surgery and that increased survival time does not necessarily increase the risk of developing a perineal hernia. This may be due to improved surgical technique and closure with porcine mesh. Disclosure of interest None Declared.

Lack of identifiable biologic behavior in a series of porcine mesh explants

Biologic matrices used in abdominal wall reconstruction are purported to undergo remodeling into connective tissue resembling native collagen. Key steps in that process include inflammatory response at the mesh/tissue interface, cellular penetration, and neovascularization of the matrix, followed by fibroblast proliferation and collagen deposition. We aimed to examine the concept of biologic mesh remodeling/regeneration in a series of explanted porcine biologic meshes. A cohort of patients who underwent removal of porcine biologic mesh was identified in a prospective database. Mesh/tissue samples were analyzed using standard hematoxylin/eosin and Masson's trichrome staining. Main outcome measures included: inflammatory response at the mesh/tissue interface, foreign body reaction (FBR), cellular penetration, neovascularization, and new collagen deposition. All evaluations were performed by a blinded senior pathologist using established grading scales. A total of 14 cases with implant time ranging from 4 to 33 months were identified and analyzed. All meshes were placed as intraperitoneal underlay. There were 7 non-cross-linked and 7 cross-linked grafts. Cross-linked grafts were associated with mild FBR and moderate fibrous capsule formation. Similarly, non-cross-linked grafts had mild-to-moderate FBR and encapsulation. Furthermore, non-cross-linked grafts were associated with no neovascularization and minimal peripheral mesh neocellularization. Cross-linked grafts demonstrated neither neovascularization nor neocellularization. Although no grafts were associated with any quantifiable new collagen deposition within the porcine biologic matrix, minimal biodegradation/remodeling was observed at the periphery of the non-cross-linked grafts only. The biologic behavior of porcine meshes is predicated on their ability to undergo mesh remodeling with resorption and new collagen deposition. In the largest series of human biologic explants, we detected no evidence of xenograft remodeling, especially in the cross-linked group. Although underlay mesh placement and other patient factors may have contributed to our findings, the concept of porcine biologic mesh regeneration does not seem to be prevalent in the clinical setting.

Early report of a randomized comparative clinical trial of Strattice™ reconstructive tissue matrix to lightweight synthetic mesh in the repair of inguinal hernias

Biologic grafts are rarely used for inguinal herniorrhaphy. The aim of this study was to compare the clinical outcomes between patients undergoing a Lichtenstein's hernioplasty with a porcine mesh versus a standard synthetic. A prospective, randomized, double-blinded multicenter, evaluation of inguinal hernia repair was conducted between 2008 and 2010. Lichtenstein hernioplasty was performed using Strattice™ or lightweight polypropylene (Ultrapro) mesh. Quality of life, pain, overall complication rate, and recurrence were measured. One hundred and seventy-two patients were randomized to Strattice™ (n = 84) or Ultrapro (n = 88). At 3 months postoperatively, there were no differences on the occurrence or type of wound events [RR: 0.98 (95% CI 0.52-1.86, p = 0.69), Strattice™ (15 events) vs. Ultrapro (16 events)]. The mean level of impairment caused by the hernia, assessed by Activities Assessment Scale (AAS), significantly decreased postoperatively in both groups at 3 months (31% Strattice™ and 37% Ultrapro). Patients in the Strattice group reported significantly less postoperative pain during postoperative days 1 through 3 compared to Ultrapro patients. However, the amount of postoperative pain at 3 months, as assessed by the mean worst pain score on a visual analog scale and the Brief Pain Index, was similar between groups (95% CI 1.0-29.3). No hernia recurrences were observed in either group. Strattice™ is safe and effective in repairing inguinal hernia, with comparable intra-operative and early postoperative morbidity to synthetic mesh. Long-term follow-up is necessary in order to know whether the clinical outcomes of Strattice are equivalent to standard synthetic mesh in patients undergoing Lichtenstein's hernioplasty.

Combination of tissue expansion and porcine mesh for secondary abdominal wall closure after pediatric liver transplantation

We report the case of a two and a half yr boy hospitalized in our Pediatric Transplantation Unit for portal vein thrombosis following liver transplantation. After performing a meso-Rex shunt, abdominal wall closure was impossible without compressing the portal flow. A combination of two techniques was used to perform the reconstruction of the muscular fasciae and skin layers. The association of tissue expanders and porcine mesh (Surgisis(®)) allowed complete abdominal wall closure with good functional and esthetic results. Use of both techniques is a useful alternative for difficult abdominal closure after liver pediatric transplantation.

The Addition of Lysostaphin Dramatically Improves Survival, Protects Porcine Biomesh from Infection, and Improves Graft Tensile Shear Strength

Lysostaphin (LS), a naturally occurring Staphylococcal endopeptidase, has the ability to penetrate biofilm, and has been identified as a potential antimicrobial to prevent mesh infection. The goals of this study were to determine if LS adhered to porcine mesh (PM) can impact host survival, reduce the risk of long-term PM infection, and to analyze lysostaphin bound PM (LS-PM) mesh-fascial interface in an infected field. Abdominal onlay PMs measuring 3×3 cm were implanted in select groups of rats (n=75). Group assignments were based on bacterial inoculum and presence of LS on mesh. Explantation occurred at 60 d. Bacterial growth and mesh-fascial interface tensile strength were analyzed. Standard statistical analysis was performed. Only one out of 30 rats with bacterial inoculum not treated with LS survived. All 30 LS treated rats survived and had normal appearing mesh, including 20 rats with a bacterial inoculum (10(6) and 10(8) CFU). Mean tensile strength for controls and LS and no inoculum samples was 3.47±0.86 N versus 5.0±1.0 N (P=0.008). LS groups inoculated with 10(6) and 10(8) CFU exhibited mean tensile strengths of 4.9±1.5 N and 6.7±1.6 N, respectively (P=0.019 and P<0.001 compared with controls). Rats inoculated with S. aureus and not treated with LS had a mortality of 97%. By comparison, LS treated animals completely cleared S. aureus when challenged with bacterial concentrations of 1×10(6) and 1×10(8) with maintenance of mesh integrity at 60 d. These findings strongly suggest the clinical use of LS-treated porcine mesh in contaminated fields may translate into more durable hernia repair.

The effect of biological and synthetic meshes on vaginal smooth muscle cell proliferation

To compare the effects of polypropylene mesh or porcine dermal acellular collagen matrix mesh with and without estradiol supplementation on vaginal smooth muscle cells (VaSMC) proliferation. Under in vitro culture conditions, VaSMC proliferation was significantly higher in the porcine dermal acellular collagen matrix mesh exposed cells compared to the type I polypropylene mesh exposed cells (relative cell number, mean ± SD, 0.27 ± 0.03 vs. 0.21 ± 0.01, P = 0.03). Under estradiol supplementation cell proliferation in the porcine mesh exposed cells remained significantly higher compared to the polypropylene mesh exposed cells (relative cell number, mean ± SD, 0.27 ± 0.04 vs. 0.15 ± 0.03, P < 0.01). The decreased rate of erosion found with the utilization of biological absorbable mesh in vaginal reconstructive surgery may partially be explained by the significantly increased VaSMC proliferation with porcine dermal acellular collagen mesh compared to polypropylene mesh.

Repair of High-Risk Incisional Hernias and Traumatic Abdominal Wall Defects with Porcine Mesh

Complex ventral hernias represent a significant challenge to surgeons. We hypothesized that a wide underlay technique in combination with a novel biologic mesh would result in repair with a low recurrence rate. Medical records of patients undergoing ventral herniorrhaphy with XenMatrix biologic mesh were evaluated. All patients were evaluated for hernia recurrence both immediately and after 2 to 3 years. There were 57 patients included in the study. The overall recurrence rate was 7.2 per cent; however, all recurrences were early and were likely technical failures. The average duration of follow-up was 30.6 months with no further recurrences after the early technical failures. The average number of previous recurrences was 1.5. Fascial closure was obtained over the mesh in 84 per cent of patients, with component separation being necessary in 36 per cent of patients. Lack of fascial reapproximation over the mesh was associated with early recurrence (0 vs 55%, P < 0.0001). Complex ventral hernias can be repaired with a low recurrence rate. Our technique in combination with the XenMatrix biologic mesh provides for durable repair. Whenever possible, the fascia should be closed above the underlay mesh, because this technique provides a more durable repair than using the mesh as a "fascial bridge".

Fibrin glue and porcine-derived mesh repair of ruptured umbilical hernia in a patient with ascites

BACKGROUND: Rupture of an umbilical hernia carries a risk of high mortality for patients with liver failure complicated by ascites. There is no consensus on the management of this condition, as it has been managed both conservatively and operatively. METHODS: We report a case which demonstrates a unique surgical approach to the management of a spontaneous rupture of an umbilical hernia in a patient with liver cirrhosis and ascites with the porcine-derived mesh and Tisseel™ fibrin glue. RESULTS: The wound has remained intact and there is no recurrence at his twelve-month follow-up. CONCLUSIONS: We report the feasible use of Tisseel™ fibrin glue with porcine mesh to successfully repair a ruptured umbilical hernia in a cirrhotic patient with gross ascites.

The Addition Of Lysostaphin Dramatically Improves Survival, Protects Porcine Biomesh From Infection, And Improves Graft Tensile Shear Strength

Introduction: Staphylococcus aureus (S. aureus) is the causative agent in up to 90% of mesh infections. The pathogenesis of S. aureus is related to its ability to form biofilm, which is widely implicated in many implant-based and chronic infections. Lysostaphin (LS), a naturally occurring Staphylococcal endopeptidase, has the ability to penetrate biofilm and has been identified as a potential antimicrobial to prevent mesh infection. The goals of this study were to determine if LS adhered to porcine mesh (PM) can impact host survival, reduce the risk of long-term PM infection, and to analyze lysostaphin bound PM (LS-PM) mesh-fascial interface in an infected field.

Vaginal reconstruction following supra-levator total pelvic exenteration

Background There are several available techniques for neovaginal reconstruction following exenterative gynecologic surgery. However, all methods are associated with prolonged operative time and increased morbidity. The Apogee and Perigee™ vaginal vault and prolapse repair systems are innovative and minimally invasive procedures that may prove to be effective in controlling the levator defect and reconstructing the vagina in patients undergoing supra-levator pelvic exenteration. Case We present a patient who underwent supra-levator total pelvic exenteration for treatment of recurrent squamous cell carcinoma of the cervix. Vaginal reconstruction was performed with the Apogee and Perigee systems utilizing the porcine mesh (InteXen) from American Medical Systems. The patient did well without any postoperative vaginal or small bowel complications. Conclusion The Apogee and Perigee systems comprise an innovative technique for vaginal vault reconstruction and prolapse repair. These systems may prove useful in reconstruction of the pelvis following ultra-radical pelvic procedures for recurrent gynecologic malignancies.