Biology of biological meshes used in hernia repair

Transversalis fascia suture reinforcement may facilitate the performance of electrospun P(LLA-CL) nanoscale fibrinogen mesh in inguinal hernia repair: a prospective single-center cohort study

The aim of this study was to evaluate a new electrospun P(LLA-CL) nanoscale fibrinogen mesh performance in real-world clinical practice. A prospective, single-center evaluation of Lichtenstein inguinal hernia repair using electrospun P(LLA-CL) nanoscale fibrinogen mesh in elderly patients with comorbid diseases was conducted between 2020 and 2022. A suture reinforcement of transversalis fascia was applied before mesh implantation. Hernia recurrence, pain score and overall complication rate were measured. A total of 52 inguinal hernias in 48 patients were included. The age of patients ranged from 33 to 95 years, with a median of 78 years. Comorbid conditions included cardiopulmonary disease, organ dysfunction, anticoagulant use, diabetes and smoking. By optimizing the physical condition perioperatively, all patients finished treatment successfully. Four cases recurred secondary to direct hernias or combined hernias and were diagnosed in the first 24 case cohort during follow-up. With surgical procedural modification involving strengthening the posterior inguinal floor by reef-up suturing of the transversalis fascia and the inferior edge of mesh slit to accommodate the spermatic cord, no further recurrence was diagnosed. Postoperative pain was mild and the pain score decreased three months after surgery compared to 1 week after surgery (p = 0.0099). No severe complications occurred, while seroma occurred in six cases. Electrospun P(LLA-CL) nanoscale fibrinogen mesh is safe and effective in repairing inguinal hernias in elderly patients with comorbid disease. A strengthening of the transversalis fascia by suturing may enhance the performance of this mesh.

[Results of abdominal wall closure using the 4:1 suture/wound lenght technique]

Background

Laparotomy is a daily procedure for the general surgeon and its main complication is the formation of hernias.

Objective

To determine if the suture length to wound length ratio 4:1 for wall closure decreases the incidence of hernia.

Material and methods

Data from patients (n = 86) in whom abdominal wall closure was performed from August 2017 to January 2018 were prospectively reviewed. Patients who could not undergo adequate follow-up, those managed with open abdomen, or those with use of non-absorbable suture materials were excluded. 2 groups were formed: in one, the suture length to wound length ratio 4:1 technique was used as wall closure, and in the other it was used conventional suture; the length of the wound-suture length was measured, and the follow-up was post-surgical. For statistical analysis it was used descriptive statistics and inferential statistics (chi-squared and Mann-Withney's U).

Results

The 2 groups had similar characteristics in all the inclusion criteria. There was a statistically significant difference in dehiscence and hernias. For both complications, the 4:1 suture is a protective factor. For the first it was obtained: p = 0.000, relative risk (RR) 0.114 with 95% confidence interval (95% CI) 0.030-0.437, and for the second, p = 0.000, RR .091, 95% CI 0.027-0.437.

Conclusions

Abdominal wall closure using 4:1 suture/wound length was shown to decrease the incidence of hernia.

Platelet-rich plasma enhances mechanical strength of strattice in rat model of ventral hernia repair

Incisional hernia is a common complication of hernia repair despite the development of various synthetic and bio-synthetic repair materials. Poor long-term mechanical strength, leading to high recurrence rates, has limited the use of acellular dermal matrices (ADMs) in ventral hernia repair (VHR). Biologically derived meshes have been an area of increasing interest. Still these materials bring the risk of more aggressive immune response and fibrosis in addition to the mechanical failures suffered by the synthetic materials. Platelet-rich plasma (PRP), a growth-factor-rich autologous blood product, has been shown to improve early neovascularization, tissue deposition, and to decrease the rates of recurrence. Here, we demonstrate that PRP promotes the release of growth factors stromal derived factor (SDF)-1, transforming growth factor-beta, and platelet-derived growth factor in a dose-dependent manner. Additionally, we utilize an aortic ring angiogenesis assay to show that PRP promotes angiogenesis in vitro. A rat model of VHR using StratticeTM ADM demonstrates similar findings in vivo, corresponding with the increased expression of vascular endothelial growth factor and collagen type 1 alpha 1. Finally, we show that the molecular and cellular activity initiated by PRP results in an increased mechanical stiffness of the hernia repair mesh over time. Collectively, these data represent an essential step in demonstrating the utility and the mechanism of platelet-derived plasma in biomaterial-aided wound healing and provide promising preclinical data that suggest such materials may improve surgical outcomes.

Prevention of incisional hernia at the site of stoma closure with different reinforcing mesh types: a systematic review and meta-analysis

Purpose

To evaluate safety and efficacy of a mesh reinforcement following stoma reversal to prevent stoma site incisional hernia (SSIH) and differences across the prostheses used.

Methods

A systematic search of PubMed/MEDLINE, EMBASE, SCOPUS and Cochrane databases was conducted to identify comparative studies until September 2020. A meta-analysis of postoperative outcomes and a network meta-analysis for a multiple comparison of the prostheses with each other were performed.

Results

Seven studies were included in the analysis (78.4% ileostomy and 21.6% colostomy) with a total of 1716 patients with (n = 684) or without (n = 1032) mesh. Mesh placement was associated with lower risk of SSIH (7.8%vs18.1%, OR0.266,95% CI 0.123–0.577, p < 0.001) than no mesh procedures but also with a longer operative time (SMD 0.941, 95% CI 0.462–1.421, p < 0.001). There was no statistically significant difference in terms of Surgical Site infection (11.5% vs 11.1%, OR 1.074, 95% CI 0.78–1.48, p = 0.66), seroma formation (4.4% vs 7.1%, OR 1.052, 95% CI 0.64–1.73, p = 0.84), anastomotic leakage (3.7% vs 2.7%, OR 1.598, 95% CI 0.846–3.019, p = 0.149) and length of stay (SMD − 0.579,95% CI − 1.261 to 0.102, p = 0.096) between mesh and no mesh groups. Use of prosthesis was associated with a significant lower need for a reoperation than no mesh group (8.1% vs 12.1%, OR 0.332, 95% CI 0.119–0.930, p = 0.036). Incidence of seroma is lower with biologic than polypropylene meshes but they showed a trend towards poor results compared with polypropylene or biosynthetic meshes.

Conclusion

Despite longer operative time, mesh prophylactic reinforcement at the site of stoma seems a safe and effective procedure with lower incidence of SSIH, need for reoperation and comparable short-term outcomes than standard closure technique. A significant superiority of a specific mesh type was not identified.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10029-021-02393-w.

Decellularized xenografts in regenerative medicine: From processing to clinical application

Decellularized xenografts are an inherent component of regenerative medicine. Their preserved structure, mechanical integrity and biofunctional composition have well established them in reparative medicine for a diverse range of clinical indications. Nonetheless, their performance is highly influenced by their source (ie species, age, tissue) and processing (ie decellularization, crosslinking, sterilization and preservation), which govern their final characteristics and determine their success or failure for a specific clinical target. In this review, we provide an overview of the different sources and processing methods used in decellularized xenografts fabrication and discuss their effect on the clinical performance of commercially available decellularized xenografts.

Evaluation of decellularization protocols for production of porcine small intestine submucosa for use in abdominal wall reconstruction

BACKGROUND

Porcine-derived acellular biologic grafts are increasingly used in abdominal wall reconstruction and other soft tissue repairs. In a previous work, we have shown porcine small intestine submucosa (PSIS) exhibits clear advantages over porcine pericardium (PPC) and porcine acellular dermal matrix (PADM) in repairing full-thickness abdominal wall defects. In the present study, we aim to determine, quantify, and compare the effects of two most commonly used decellularization protocols on biomechanical and biocompatible properties of PSIS.

MATERIALS AND METHODS

After mechanical preparation, PSIS was treated with either alkaline and acid (AA) protocol or sodium dodecyl sulfate (SDS) protocol. Cellular content removal, preservation of matrix components, micro- and ultra- structures, and mechanical properties were compared. The host responses were evaluated using PSIS for repairing rat abdominal wall defects.

RESULTS AND CONCLUSION

With regard to the absence of cellular contents, neatly arranged collagen fiber structures, better retention of growth factors, better mechanical strength, lower degrees of local and systemic inflammatory responses, higher degree of vascularization and tissue ingrowth, alkaline and acid protocol exhibits clear advantages over SDS protocol for the preparation of PSIS extracellular matrix.

Biomaterial Implants in Abdominal Wall Hernia Repair: A Review on the Importance of the Peritoneal Interface

Biomaterials have long been used to repair defects in the clinical setting, which has led to the development of a wide variety of new materials tailored to specific therapeutic purposes. The efficiency in the repair of the defect and the safety of the different materials employed are determined not only by the nature and structure of their components, but also by the anatomical site where they will be located. Biomaterial implantation into the abdominal cavity in the form of a surgical mesh, such as in the case of abdominal hernia repair, involves the contact between the foreign material and the peritoneum. This review summarizes the different biomaterials currently available in hernia mesh repair and provides insights into a series of peculiarities that must be addressed when designing the optimal mesh to be used in this interface.

Updates in Mesh and Biomaterials

Prior publications of the Surgical Clinics of North America have highlighted the technical challenges of abdominal wall reconstruction. This article provides an update on synthetic, biologic, and biosynthetic mesh research since the 2013 Surgical Clinics of North America hernia publication and highlights the future of mesh research. This update features research that has been conducted since the prior publication to guide surgeons to choose the best and most appropriate mesh for their patients.

Evaluation of Sidestream Darkfield Microscopy for Real-Time Imaging Acellular Dermal Matrix Revascularization

BACKGROUND

Acellular dermal matrices (ADMs) serve as a regenerative framework for host cell integration and collagen deposition to augment the soft tissue envelope in ADM-assisted breast reconstruction-a process dependent on vascular ingrowth. To date noninvasive intra-operative imaging techniques have been inadequate to evaluate the revascularization of ADM.

METHODS

We investigated the safety, feasibility, and efficacy of sidestream darkfield (SDF) microscopy to assess the status of ADM microvascular architecture in 8 patients at the time of tissue expander to permanent implant exchange during 2-stage ADM-assisted breast reconstruction. The SDF microscopy is a handheld device, which can be used intraoperatively for the real-time assessment of ADM blood flow, vessel density, vessel size, and branching pattern. The SDF microscopy was used to assess the microvascular architecture in the center and border zone of the ADM and to compare the native, non-ADM-associated capsule in each patient as a within-subject control.

RESULTS

No incidences of periprosthetic infection, explantation, or adverse events were reported after SDF image acquisition. Native capsules demonstrate a complex, layered architecture with an average vessel area density of 14.9 mm/mm and total vessel length density of 12.3 mm/mm. In contrast to native periprosthetic capsules, ADM-associated capsules are not uniformly vascularized structures and demonstrate 2 zones of microvascular architecture. The ADM and native capsule border zone demonstrates palisading peripheral vascular arcades with continuous antegrade flow. The central zone of the ADM demonstrates punctate perforating vascular plexi with intermittent, sluggish flow, and intervening 2- to 3-cm watershed zones.

CONCLUSIONS

Sidestream darkfield microscopy allows for real-time intraoperative assessment of ADM revascularization and serves as a potential methodology to compare revascularization parameters among commercially available ADMs. Thr SDF microscopy demonstrates that the periprosthetic capsule in ADM-assisted implant-based breast reconstruction is not a uniformly vascularized structure.

First human use of hybrid synthetic/biologic mesh in ventral hernia repair: a multicenter trial. Surg Endosc. 2018;32:1123-1130. [PMID: 28726148 DOI: 10.1007/s00464-017-5715-6]

BACKGROUND

Mesh options for reinforcement of ventral/incisional hernia (VIH) repair include synthetic or biologic materials. While each material has known advantages and disadvantages, little is understood about outcomes when these materials are used in combination. This multicenter study reports on the first human use of a novel synthetic/biologic hybrid mesh (Zenapro^® Hybrid Hernia Repair Device) for VIH repair.

METHODS

This prospective, multicenter post-market clinical trial enrolled consecutive adults who underwent elective VIH repair with hybrid mesh placed in the intraperitoneal or retromuscular/preperitoneal position. Patients were classified as Ventral Hernia Working Group (VHWG) grades 1-3 and had clean or clean-contaminated wounds. Outcomes of ventral and incisional hernia were compared using appropriate parametric tests.

RESULTS

In all, 63 patients underwent VIH repair with hybrid mesh. Most were females (54.0%), had a mean age of 54.8 ± 10.9 years and mean body mass index of 34.5 ± 7.8 kg/m², and classified as VHWG grade 2 (87.3%). Most defects were midline (92.1%) with a mean area of 106 ± 155 cm². Cases were commonly classified as clean (92.1%) and were performed laparoscopically (60.3%). Primary fascial closure was achieved in 82.5% with 28.2% requiring component separation. Mesh location was frequently intraperitoneal (69.8%). Overall, 39% of patients available for follow-up at 12 months suffered surgical site events, which were generally more frequent after incisional hernia repair. Of these, seroma (23.7%) was most common, but few (8.5%) required procedural intervention. Other surgical site events that required procedural intervention included hematoma (1.7%), wound dehiscence (1.7%), and surgical site infection (3.4%). Recurrence rate was 6.8% (95% CI 2.2-16.6%) at 12-months postoperatively.

CONCLUSION

Zenapro^® Hybrid Hernia Repair Device is safe and effective in VHWG grade 1-2 patients with clean wounds out to 12 months. Short-term outcomes and recurrence rate are acceptable. This hybrid mesh represents a novel option for reinforcement during VIH repair.

Biomimetic collagen/elastin meshes for ventral hernia repair in a rat model

Ventral hernia repair remains a major clinical need. Herein, we formulated a type I collagen/elastin crosslinked blend (CollE) for the fabrication of biomimetic meshes for ventral hernia repair. To evaluate the effect of architecture on the performance of the implants, CollE was formulated both as flat sheets (CollE Sheets) and porous scaffolds (CollE Scaffolds). The morphology, hydrophylicity and in vitro degradation were assessed by SEM, water contact angle and differential scanning calorimetry, respectively. The stiffness of the meshes was determined using a constant stretch rate uniaxial tensile test, and compared to that of native tissue. CollE Sheets and Scaffolds were tested in vitro with human bone marrow-derived mesenchymal stem cells (h-BM-MSC), and finally implanted in a rat ventral hernia model. Neovascularization and tissue regeneration within the implants was evaluated at 6weeks, by histology, immunofluorescence, and q-PCR. It was found that CollE Sheets and Scaffolds were not only biomechanically sturdy enough to provide immediate repair of the hernia defect, but also promoted tissue restoration in only 6weeks. In fact, the presence of elastin enhanced the neovascularization in both sheets and scaffolds. Overall, CollE Scaffolds displayed mechanical properties more closely resembling those of native tissue, and induced higher gene expression of the entire marker genes tested, associated with de novo matrix deposition, angiogenesis, adipogenesis and skeletal muscles, compared to CollE Sheets. Altogether, this data suggests that the improved mechanical properties and bioactivity of CollE Sheets and Scaffolds make them valuable candidates for applications of ventral hernia repair.

STATEMENT OF SIGNIFICANCE

Due to the elevated annual number of ventral hernia repair in the US, the lack of successful grafts, the design of innovative biomimetic meshes has become a prime focus in tissue engineering, to promote the repair of the abdominal wall, avoid recurrence. Our meshes (CollE Sheets and Scaffolds) not only showed promising mechanical performance, but also allowed for an efficient neovascularization, resulting in new adipose and muscle tissue formation within the implant, in only 6weeks. In addition, our meshes allowed for the use of the same surgical procedure utilized in clinical practice, with the commercially available grafts. This study represents a significant step in the design of bioactive acellular off-the-shelf biomimetic meshes for ventral hernia repair.

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

BACKGROUND

A 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.

METHODS

Biologic 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.

RESULTS

28 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.

CONCLUSIONS

Permacol™ 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.

Is there a place for a biological mesh in perineal hernia repair?

Purpose

This study aimed to determine the outcome of perineal hernia repair with a biological mesh after abdominoperineal resection (APR).

Method

All consecutive patients who underwent perineal hernia repair with a porcine acellular dermal mesh between 2010 and 2014 were included. Follow-up was performed by clinical examination and MRI.

Results

Fifteen patients underwent perineal hernia repair after a median of 25 months from APR. Four patients had a concomitant contaminated perineal defect, for which a gluteal fasciocutaneous flap was added in three patients. Wound infection occurred in three patients. After a median follow-up of 17 months (IQR 12–24), a clinically recurrent perineal hernia developed in 7 patients (47 %): 6 of 11 patients after a non-cross-linked mesh and 1 of 4 patients after a cross-linked mesh (p = 0.57). Routine MRI at a median of 17 months revealed a recurrent perineal hernia in 7 of 10 evaluable patients, with clinical confirmation of recurrence in 5 of these 7 patients. No recurrent hernia was observed in the three patients with combined flap reconstruction for contaminated perineal defects.

Conclusion

A high recurrence rate was observed after biological mesh repair of a perineal hernia following APR.

Which mesh or graft? Prosthetic devices for abdominal wall reconstruction

This article reviews the ever-increasing number of prosthetic devices--both synthetic mesh and biologic grafts--now in use for abdominal wall reconstruction. It also introduces a novel hybrid synthetic/biologic graft (Zenapro) and suture passer device (Novapass).

Attachment of Primary Vaginal Fibroblasts to Absorbable and Nonabsorbable Implant Materials Coated With Platelet-Rich Plasma: Potential Application in Pelvic Organ Prolapse Surgery

OBJECTIVES

Pelvic organ prolapse (POP) is a common condition in women. The lifetime risk of undergoing surgery to correct POP is 11%, with 30% recurrence rate. Various types of vaginal implants, absorbable and nonabsorbable, that have been introduced in pelvic floor reconstructive surgeries have numerous serious adverse effects. Platelet-rich plasma (PRP) is an autologous product that accelerates tissue healing and regeneration. We hypothesized that autologous PRP will promote human vaginal fibroblast (HVF) attachment to vaginal implants and increase their healing potential.

METHODS

Vaginal tissue biopsies were collected from postmenopausal patients with POP (n = 10) and asymptomatic control subjects (n = 4) during vaginal hysterectomy or repair. Primary cells were isolated and characterized by immunocytochemistry. Cell attachment and proliferation were compared between POP HVFs and control HVFs (n = 4/group). Twelve weeks after the surgery, blood samples were collected from 6 POP patients to obtain autologous PRP. Two meshes, absorbable (Vicryl) and nonabsorbable (Restorelle), were coated in PRP or control media; autologous POP HVFs (n = 6) were seeded on meshes for 2 hours. Cells attached to the meshes were fixed, stained with DAPI (4,6-diamidino-2-phenylindole dihydrochloride), and counted.

RESULTS

Pelvic organ prolapse HVFs were similar to control HVFs in attachment to different matrix substrates and in proliferation rate. Attachment of POP HVFs to both meshes was significantly increased after coating with PRP versus Dulbecco modified Eagle medium (Vicryl: 9875 vs. 1006 cells/cm, Restorelle: 3724 vs. 649 cells/cm; P < 0.001 for both).

CONCLUSIONS

In vitro, primary POP HVFs show better attachment to implant materials when treated with PRP, which may lead to reduced mesh-related complications in vivo, indicating its great potential for urogynecologic surgeries.

Comparison of Porcine Small Intestinal Submucosa versus Polypropylene in Open Inguinal Hernia Repair: A Systematic Review and Meta-Analysis

Background

A systematic review and meta-analysis was performed in randomized controlled trials (RCTs) to compare porcine small intestinal submucosa (SIS) with polypropylene in open inguinal hernia repair.

Method

Electronic databases MEDLINE, Embase, and the Cochrane Library were used to compare patient outcomes for the two groups via meta-analysis.

Result

A total of 3 randomized controlled trials encompassing 200 patients were included in the meta-analysis. There was no significant difference in recurrence (P = 0.16), hematomas (P = 0.06), postoperative pain within 30 days (P = 0.45), or postoperative pain after 1 year (P = 0.12) between the 2 groups. The incidence of discomfort was significantly lower (P = 0.0006) in the SIS group. However, the SIS group experienced a significantly higher incidence of seroma (P = 0.03).

Conclusions

Compared to polypropylene, using SIS in open inguinal hernia repair is associated with a lower incidence of discomfort and a higher incidence of seroma. However, well-designed larger RCT studies with a longer follow-up period are needed to confirm these findings.

Synthetic Mesh Repair for Incisional Hernia Treatment in High-risk Patients for Surgical Site Occurrences

Patients with incisional hernias (IH) and risk factors for surgical site occurrences (SSOs) such as defined comorbidities and/or potential contaminations are considered to be treated with bioprosthetics. A retrospective analysis of consecutive patients who had undergone elective IH repair with synthetic mesh materials between 2009 and 2013 was conducted. Only patients who were classified into Grades II and III according to the classification of the Ventral Hernia Working Group (VHWG) were considered for the study. Primary outcome parameter was the incidence of SSO. The relationships among demographics, hernia characteristics, surgical technique, and SSOs were also evaluated. Overall, 108 patients were included (Grade II: 68, Grade III: 40). SSO was identified in 14 patients. Having two or more comorbidities ( P = 0.04), an open sublay technique ( P = 0.005), duration of operation ( P = 0.02), larger hernia defects ( P = 0.001), and using larger mesh sizes ( P = 0.01) were associated with significantly higher rates of SSO. Affiliation to VHWG Grading II or III showed no impact on SSO occurrence. Synthetic mesh repair both in an “open sublay” and laparoscopic intraperitoneal technique is safe regarding patients with risk factors for SSO. The recommendations of the VHWG must be declined and a modification of the grading system is warranted overlooking a more liberal use of synthetic meshes.