Absorbable versus nonabsorbable mesh repair of congenital diaphragmatic hernias in a growing animal model

Diaphragmatic hernia repair porcine model to compare the performance of biodegradable membranes against Gore-Tex®

BACKGROUND

Patch repair of congenital diaphragmatic hernia (CDH) using Gore-Tex® is associated with infection, adhesions, hernia recurrence, long-term musculoskeletal sequels and poor tissue regeneration. To overcome these limitations, the performance of two novel biodegradable membranes was tested to repair CDH in a growing pig model.

METHODS

Twelve male pigs were randomly assigned to 3 different groups of 4 animals each, determined by the type of patch used during thoracoscopic diaphragmatic hernia repair (Gore-Tex®, polycaprolactone electrospun membrane-PCLem, and decellularized human chorion membrane-dHCM). After 7 weeks, all animals were euthanized, followed by necropsy for diaphragmatic evaluation and histological analysis.

RESULTS

Thoracoscopic defect creation and diaphragmatic repair were performed without any technical difficulty in all groups. However, hernia recurrence rate was 0% in Gore-Tex®, 50% in PCLem and 100% in dHCM groups. At euthanasia, Gore-Tex® patches appeared virtually unchanged and covered with a fibrotic capsule, while PCLem and dHCM patches were replaced by either floppy connective tissue or vascularized and floppy regenerated membranous tissue, respectively.

CONCLUSION

Gore-Tex® was associated with a higher survival rate and lower recurrence. Nevertheless, the proposed biodegradable membranes were associated with better tissue integration when compared with Gore-Tex®.

A Systematic Review Examining the Experimental Methodology Behind In Vivo Testing of Hiatus Hernia and Diaphragmatic Hernia Mesh

INTRODUCTION

Mesh implants are regularly used to help repair both hiatus hernias (HH) and diaphragmatic hernias (DH). In vivo studies are used to test not only mesh safety, but increasingly comparative efficacy. Our work examines the field of in vivo mesh testing for HH and DH models to establish current practices and standards.

METHOD

This systematic review was registered with PROSPERO. Medline and Embase databases were searched for relevant in vivo studies. Forty-four articles were identified and underwent abstract review, where 22 were excluded. Four further studies were excluded after full-text review-leaving 18 to undergo data extraction.

RESULTS

Of 18 studies identified, 9 used an in vivo HH model and 9 a DH model. Five studies undertook mechanical testing on tissue samples-all uniaxial in nature. Testing strip widths ranged from 1-20 mm (median 3 mm). Testing speeds varied from 1.5-60 mm/minute. Upon histology, the most commonly assessed structural and cellular factors were neovascularisation and macrophages respectively (n = 9 each). Structural analysis was mostly qualitative, where cellular analysis was equally likely to be quantitative. Eleven studies assessed adhesion formation, of which 8 used one of four scoring systems. Eight studies measured mesh shrinkage.

DISCUSSION

In vivo studies assessing mesh for HH and DH repair are uncommon. Within this relatively young field, we encourage surgical and materials testing institutions to discuss its standardisation.

Technique and Outcomes in Laparoscopic Repair of Morgagni Hernia in Adults

Background: Morgagni hernias (MHs) are rare anteromedial congenital diaphragmatic hernias. This study describes the effectiveness of a laparoscopic approach for these defects. Methods: A prospectively collected institutional database at a tertiary referral center was queried for patients (≥18 years) with MHs. Results: Fifteen adults underwent laparoscopic MH repair. Abdominal pain was the most common presentation (71.5%), and 2 patients (13.3%) presented with acute obstruction. Laparoscopic bridged mesh repair was the most common approach (66.7%) and was achieved by suturing a bridged synthetic mesh to the diaphragmatic portion of the defect and fixing it with transfascial sutures and/or tacks to the anterior abdominal wall. Primary suture repair was utilized for smaller defects. No mortalities or recurrences occurred after 20.2 months median follow-up. Conclusions: Laparoscopic synthetic mesh repair of adult MHs offers an effective hernia repair with minimal complications and no detected recurrences in long-term follow-up of this patient sample.

Scaffold-Free Bio-3D Printing Using Spheroids as "Bio-Inks" for Tissue (Re-)Construction and Drug Response Tests

In recent years, scaffold-free bio-3D printing using cell aggregates (spheroids) as "bio-inks" has attracted increasing attention as a method for 3D cell construction. Bio-3D printing uses a technique called the Kenzan method, wherein spheroids are placed one-by-one in a microneedle array (the "Kenzan") using a bio-3D printer. The bio-3D printer is a machine that was developed to perform bio-3D printing automatically. Recently, it has been reported that cell constructs can be produced by a bio-3D printer using spheroids composed of many types of cells and that this can contribute to tissue (re-)construction. This progress report summarizes the production and effectiveness of various cell constructs prepared using bio-3D printers. It also considers the future issues and prospects of various cell constructs obtained by using this method for further development of scaffold-free 3D cell constructions.

In Vivo Evaluation of the Biocompatibility of Biomaterial Device

Biomaterials are widely used to produce devices for regenerative medicine. After its implantation, an interaction between the host immune system and the implanted biomaterial occurs, leading to biomaterial-specific cellular and tissue responses. These responses may include inflammatory, wound healing responses, immunological and foreign-body reactions, and even fibrous encapsulation of the implanted biomaterial device. In fact, the cellular and molecular events that regulate the success of the implant and tissue regeneration are played at the interface between the foreign body and the host inflammation, determined by innate and adaptive immune responses. This chapter focuses on host responses that must be taken into consideration in determining the biocompatibility of biomaterial devices when implanted in vivo of animal models.

Biologic Mesh Underlay in Thoracoscopic Primary Repair of Congenital Diaphragmatic Hernia Confers Reduced Recurrence in Neonates: A Preliminary Report

Purpose: The purpose of this study was to determine if utilization of biologic mesh underlay during thoracoscopic congenital diaphragmatic hernia (CDH) primary repair (PR) results in reduced 5-year hernia recurrence rates. Methods: A retrospective review was completed for all primarily repaired CDH utilizing a thoracoscopic approach from January 1, 2003 to June 31, 2013. Patients were included in the study cohort if they had a thoracoscopic PR of their CDH without any mesh reinforcement or with biologic mesh underlay. Charts were then reviewed for no less than 5 years postoperatively for reports of clinical and/or radiographic hernia recurrence. The cumulative annual hernia recurrence as well as other demographic factors were analyzed. Results: Within the study period, 46 patients were identified that met study criteria. Three patients were lost to follow-up. Fifteen of the remaining patients (15/43: 34.9%) had a biologic underlay. Within the cohort, seven recurrences were noted within 5 years of the index procedure (7/43; 16.7%). Four recurrences occurred within the first postoperative year, and all occurred by the third postoperative year. One recurrence was in a patient with a biologic underlay at 4 months after repair. This was a clinically/radiographically silent 4 mm defect and noted at laparoscopy for another indication (1/15: 6.6%). The remainder occurred in primarily repaired patients without mesh reinforcement (6/28: 21.4%). Conclusions: Thoracoscopic PR of CDH can be successfully performed in select patients. The use of a biologic mesh underlay in this subset of patients appears to confer reduced hernia recurrence.

[Diaphragmatic hernia in elective thoracic surgery]

AIM

To clarify the indications for reconstructive surgery in patients with diaphragmatic hernia.

MATERIAL AND METHODS

Retrospective trial has included 36 patients with diaphragmatic hernia for the period 1963-2017. There were 23 (63.9%) women and 13 (36.1%) men. The majority of patients (83%) underwent surgery at able-bodied age (18-60 years). 27 (75%) patients had hernia of weak diaphragmatic zones, 9 (25%) - posttraumatic hernia. Diaphragm repair was performed with primary suture. In 2 cases of posttraumatic hernia mesh endoprosthesis was used.

RESULTS

All patients were discharged. Postoperative complications arose in 4 (11.1%) patients, including 2 cases of mesh endoprosthesis deployment. Long-term outcome was followed-up in 15 patients from 6 months to 17 years. Recurrent hernia was absent in all cases.

CONCLUSION

Primary suture is acceptable for diaphragmatic hernia repair. Alloplastic repair is indicated for large defect, when primary suture is impossible or risk of its failure is high.

Emergent Laparoscopic Ventral Hernia Repairs

BACKGROUND

Emergent repairs of incarcerated and strangulated ventral hernia repairs (VHR) are associated with higher perioperative morbidity and mortality than those repaired electively. Despite increasing utilization of minimally invasive techniques in elective repairs, the role for laparoscopy in emergent VHR is not well defined, and its feasibility has been demonstrated only in single center studies.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database (2009-2016) was queried for emergent VHR. Laparoscopic and open techniques were compared using univariate and multivariate analyses.

RESULTS

A total of 11,075 patients who underwent emergent ventral and incisional hernia repairs were identified: 85.5% open ventral hernia repair (OVHR), 14.5% laparoscopic ventral hernia repair (LVHR). Patients who underwent emergent OVHRs were older, more comorbid, and more likely to be septic at the time of surgery than those undergoing emergent LVHRs. Emergent OVHR patients were more likely to have minor complications (22.1% versus 11.0%; OR 1.7; 95% CI 1.069-2.834). After controlling for confounding variables, LVHR and OVHR had similar outcomes, with the exception of higher rates of superficial surgical site infection in OVHR (5.0% versus 1.8%; odd's ratio (OR) 2.7; 95% confidence interval (CI) 1.176-6.138). Following multivariate analysis, laparoscopic approach demonstrated similar outcomes in major complications, reoperation, and 30-d mortality compared to open repairs. However, when controlling for other confounding factors, LVHR had reduced length of stay compared to OVHR (6.7 versus 4.0 d; 1.6 d longer, standard error 0.77, P < 0.03).

CONCLUSIONS

Emergent LVHR is associated with fewer superficial surgical site infection and shorter length of stay than OVHR but no difference in major complications, reoperation or 30-d mortality is associated with LVHR in the emergency setting.

Congenital Diaphragmatic Hernia and Diaphragmatic Eventration

Congenital diaphragmatic hernia can be approached successfully using minimally invasive techniques. Although there are may be a suggestion of higher recurrence rates with thoracoscopic repair, this may be due to the learning curve. However, open repair is associated with additional morbidity, most notably an increased rate of small bowel obstruction. Appropriate patients who have congenital diaphragmatic hernia should be offered the benefits of minimally invasive repair.

A growing animal model for neonatal repair of large diaphragmatic defects to evaluate patch function and outcome

Objectives

We aimed to develop a more representative model for neonatal congenital diaphragmatic hernia repair in a large animal model, by creating a large defect in a fast-growing pup, using functional pulmonary and diaphragmatic read outs.

Background

Grafts are increasingly used to repair congenital diaphragmatic hernia with the risk of local complications. Growing animal models have been used to test novel materials.

Methods

6-week-old rabbits underwent fiberoptic intubation, left subcostal laparotomy and hemi-diaphragmatic excision (either nearly complete (n = 13) or 3*3cm (n = 9)) and primary closure (Gore-Tex patch). Survival was further increased by moving to laryngeal mask airway ventilation (n = 15). Sham operated animals were used as controls (n = 6). Survivors (90 days) underwent chest X-Ray (scoliosis), measurements of maximum transdiaphragmatic pressure and breathing pattern (tidal volume, Pdi). Rates of herniation, lung histology and right hemi-diaphragmatic fiber cross-sectional area was measured.

Results

Rabbits surviving 90 days doubled their weight. Only one (8%) with a complete defect survived to 90 days. In the 3*3cm defect group all survived to 48 hours, however seven (78%) died later (16–49 days) from respiratory failure secondary to tracheal stricture formation. Use of a laryngeal mask airway doubled 90-day survival, one pup displaying herniation (17%). Cobb angel measurements, breathing pattern, and lung histology were comparable to sham. Under exertion, sham animals increased their maximum transdiaphragmatic pressure 134% compared to a 71% increase in patched animals (p<0.05). Patched animals had a compensatory increase in their right hemi-diaphragmatic fiber cross-sectional area (p<0.0001).

Conclusions

A primarily patched 3*3cm defect in growing rabbits, under laryngeal mask airway ventilation, enables adequate survival with normal lung function and reduced maximum transdiaphragmatic pressure compared to controls.

Complications in neonatal surgery

Neonatal surgery is recognized as an independent discipline in general surgery, requiring the expertise of pediatric surgeons to optimize outcomes in infants with surgical conditions. Survival following neonatal surgery has improved dramatically in the past 60 years. Improvements in pediatric surgical outcomes are in part attributable to improved understanding of neonatal physiology, specialized pediatric anesthesia, neonatal critical care including sophisticated cardiopulmonary support, utilization of parenteral nutrition and adjustments in fluid management, refinement of surgical technique, and advances in surgical technology including minimally invasive options. Nevertheless, short and long-term complications following neonatal surgery continue to have profound and sometimes lasting effects on individual patients, families, and society.

Diaphragm Repair with a Novel Cross-Linked Collagen Biomaterial in a Growing Rabbit Model

Background

Neonates with congenital diaphragmatic hernia and large defects often require patch closure. Acellular collagen matrices (ACM) have been suggested as an alternative to synthetic durable patches as they are remodeled by the host or could also be used for tissue engineering purposes.

Materials and Methods

2.0x1.0 cm diaphragmatic defects were created in 6-weeks old New-Zealand white rabbits. We compared reconstruction with a purpose-designed cross-linked ACM (Matricel) to 4-layer non-cross-linked small intestinal submucosa (SIS) and a 1-layer synthetic Dual Mesh (Gore-Tex). Unoperated animals or animals undergoing primary closure (4/0 polyglecaprone) served as age-matched controls. 60 (n = 25) resp. 90 (n = 17) days later, animals underwent chest x-ray and obduction for gross examination of explants, scoring of adhesion and inflammatory response. Also, uniaxial tensiometry was done, comparing explants to contralateral native diaphragmatic tissue.

Results

Overall weight nearly doubled from 1,554±242 g at surgery to 2,837±265 g at obduction (+84%). X-rays did show rare elevation of the left diaphragm (SIS = 1, Gore-Tex = 1, unoperated control = 1), but no herniation of abdominal organs. 56% of SIS and 10% of Matricel patches degraded with visceral bulging in four (SIS = 3, Matricel = 1). Adhesion scores were limited: 0.5 (Matricel) to 1 (SIS, Gore-Tex) to the left lung (p = 0.008) and 2.5 (Gore-Tex), 3 (SIS) and 4 (Matricel) to the liver (p<0.0001). Tensiometry revealed a reduced bursting strength but normal compliance for SIS. Compliance was reduced in Matricel and Gore-Tex (p<0.01). Inflammatory response was characterized by a more polymorphonuclear cell (SIS) resp. macrophage (Matricel) type of infiltrate (p<0.05). Fibrosis was similar for all groups, except there was less mature collagen deposited to Gore-Tex implants (p<0.05).

Conclusions

Matricel induced a macrophage-dominated inflammatory response, more adhesions, had appropriate strength but a lesser compliance compared to native tissue. The herein investigated ACM is not a viable option for CDH repair.

Arterial grafts exhibiting unprecedented cellular infiltration and remodeling in vivo: the role of cells in the vascular wall

OBJECTIVE

To engineer and implant vascular grafts in the arterial circulation of a pre-clinical animal model and assess the role of donor medial cells in graft remodeling and function.

APPROACH AND RESULTS

Vascular grafts were engineered using Small Intestinal Submucosa (SIS)-fibrin hybrid scaffold and implanted interpositionally into the arterial circulation of an ovine model. We sought to demonstrate implantability of SIS-Fibrin based grafts; examine the remodeling; and determine whether the presence of vascular cells in the medial wall was necessary for cellular infiltration from the host and successful remodeling of the implants. We observed no occlusions or anastomotic complications in 18 animals that received these grafts. Notably, the grafts exhibited unprecedented levels of host cell infiltration that was not limited to the anastomotic sites but occurred through the lumen as well as the extramural side, leading to uniform cell distribution. Incoming cells remodeled the extracellular matrix and matured into functional smooth muscle cells as evidenced by expression of myogenic markers and development of vascular reactivity. Interestingly, tracking the donor cells revealed that their presence was beneficial but not necessary for successful grafting. Indeed, the proliferation rate and number of donor cells decreased over time as the vascular wall was dominated by host cells leading to significant remodeling and development of contractile function.

CONCLUSIONS

These results demonstrate that SIS-Fibrin grafts can be successfully implanted into the arterial circulation of a clinically relevant animal model, improve our understanding of vascular graft remodeling and raise the possibility of engineering mural cell-free arterial grafts.

Organ bioengineering for the newborn

Regenerative medicine has recently been established as an emerging interdisciplinary field focused on the repair; replacement or regeneration of cells, tissues and organs. It involves various disciplines, which are focused on different aspects of the regeneration process such as cell biology, gene therapy, bioengineering, material science and pharmacology. In this article, we will outline progress on tissue engineering of specific tissues and organs relevant to paediatric surgery.

Diaphragmatic rupture: Is management with biological mesh feasible?

INTRODUCTION

Blunt diaphragmatic rupture is a rare event that may occur after traumatic injury. Due to its rarity and difficulty in diagnosing, delayed detection of diaphragmatic injuries can occur. Management involves repair of the diaphragmatic defect via trans-thoracic and/or trans-abdominal approaches. Most small repairs may be repaired primarily, larger defects have been historically repaired with mesh.

PRESENTATION OF CASE

We report a case series of five patients with diaphragmatic injuries all repaired with biologic mesh via both trans-thoracic and trans-abdominal approaches.

DISCUSSION

Delayed presentation is the single most important contributor to increased morbidity and mortality in patients with blunt diaphragmatic rupture. Our case series corroborates other findings that patients with blunt diaphragmatic ruptures are at high risk for infection and thus may be repaired with use of biologic mesh versus the traditional use of synthetic mesh. This can be done without high rates of recurrence or complications from use of biologic mesh.

CONCLUSION

In our series, we successfully repaired 5 diaphragmatic defects with the use of biologic mesh. With follow-up as much as 4 years out, none of our patients have had an infectious complication with the use biologic mesh and there is no evidence of recurrence or eventration. The use of biologic mesh is an acceptable alternative to the traditional use of synthetic mesh in the repair of both acute and chronic diaphragmatic defects.

A review of patch options in the repair of congenital diaphragm defects

Repair of congenital diaphragmatic hernia (CDH) continues to pose a dilemma for the pediatric surgeon. While the management of CDH has evolved from surgical urgency to delayed repair after medical optimization with substantial improvements in mortality, morbidity continues to perplex clinicians. Significant morbidity occurs with recurrence, re-recurrence and complications such as obstructions, principally with mesh repair. When primary closure is not possible, mesh repair is indicated. While there are several non-absorbable prosthetic, absorbable biosynthetic and composite mesh types available, the ideal mesh remains elusive. In this article, we reviewed the current materials, reported advantages, and animal and clinical studies of non-absorbable prosthetic, absorbable biosynthetic and composite mesh. However, adequate comparative data are lacking, leaving a wide void for future animal models and clinical studies.

Congenital diaphragmatic hernia: review of current concept in surgical management

CONGENITAL DIAPHRAGMATIC HERNIAS (CDHS) OCCUR MAINLY IN TWO LOCATIONS: the foramen of Morgagni and the more common type involving the foramen of Bochdalek. Hiatal hernia and paraesophageal hernia have also been described as other forms of CDH. Pulmonary hypertension and pulmonary hypoplasia have been recognized as the two most important factors in the pathophysiology of congenital diaphragmatic hernia. Advances in surgical management include delayed surgical approach that enables preoperative stabilization, introduction of fetal intervention due to improved prenatal diagnosis, the introduction of minimal invasive surgery, in addition to the standard open repair, and the use of improved prosthetic devices for closure.