Collagen I/III and matrix metalloproteinases (MMP) 1 and 13 in the fascia of patients with incisional hernias

Genetic and biologic risk factors associated with hernia formation: A review

BACKGROUND

This systematic review aims to identify genetic and biologic markers associated with abdominal hernia formation.

METHODS

Following PRIMSA-guidelines, we searched PubMed, MEDLINE, Embase, Scopus, and COCHRANE databases.

RESULTS

Of 5946 studies, 65 were selected, excluding parastomal hernias due to insufficient data. For inguinal hernias, five studies unveiled 92 susceptible loci across 66 genes, predominantly linked to immune responses. Eleven studies observed elevated MMP-2 levels, with seven highlighting greater MMP-2 in direct compared to indirect inguinal hernias. One incisional hernia study identified unique gene-expression profiles in 174 genes associated with inflammation and cell-adhesion. In hiatal hernias, several genetic risk loci were identified. For all hernia categories, type I/III collagen ratios diminished.

CONCLUSIONS

Biological markers in inguinal hernias appears consistent. Yet, the genetic predisposition in incisional hernias remains elusive. Further research to elucidate these genetic and biological intricacies can pave the way for more individualized patient care.

Uterine scars after caesarean delivery: From histology to the molecular and ultrastructural level

Uterine rupture during a trial of labor after caesarean delivery (CD) is a serious complication for mother and fetus. The lack of knowledge on histological features and molecular pathways of uterine wound healing has hindered research in this area from evolving over time. We analysed collagen content and turnover in uterine scars on a histological, molecular and ultrastructural level. Therefore, tissue samples from the lower uterine segment were obtained during CD from 16 pregnant women with at least one previous CD, from 16 pregnant women without previous CD, and from 16 non-pregnant premenopausal women after hysterectomy for a benign disease. Histomorphometrical collagen quantification showed, that the collagen content of the scar area in uterine wall specimens after previous CD was significantly higher than in the unscarred myometrium of the same women and the control groups. Quantitative real-time PCR of uterine scar tissue from FFPE samples delineated by laser microdissection yielded a significantly higher COL3A1 expression and a significantly lower COL1A2/COL3A1 ratio in scarred uteri than in samples from unscarred uteri. Histological collagen content and the expression of COL1A2 and COL3A1 were positively correlated, while COL1A2/COL3A1 ratio was negatively correlated with the histological collagen content. Transmission electron microscopy revealed a destroyed myometrial ultrastructure in uterine scars with increased collagen density. We conclude that the high collagen content in uterine scars results from an ongoing overexpression of collagen I and III. This is a proof of concept to enable further analyses of specific factors that mediate uterine wound healing.

Similar collagen distribution in full-thickness skin grafts in intraperitoneal and onlay positions, an experimental mice-study

PURPOSE

Autologous full-thickness skin grafting (FTSG) has the potential to become an option in abdominal wall repair. An understanding of tissue remodelling in the extracellular matrix (ECM) is crucial as this interplay determines such parameters as tissue strength and flexibility. This cross-sectional preclinical laboratory study in mice provides information on the distribution of collagen types and matrix metalloproteinases (MMPs) in the ECM of FTSGs in the intraperitoneal and onlay positions compared with internal controls. The aim was to evaluate morphologic changes after tissue remodelling and repair in FTSGs applied in the two positions and to detect any adverse host response.

METHODS

ECM components were evaluated as follows: qualitative examination of collagen bundle thickness using Picrosirius Red staining (collagen types I, III and IV); and evaluation of collagen types IV and V, as well as MMPs 1, 8 and 9 using immunohistochemical staining. Full-thickness grafts transplanted between female twin mice were examined as this best mimics autologous transplantation.

RESULTS

At 8 weeks, FTSGs in the intraperitoneal position did not show any noticeable differences in morphologic appearance to those in the onlay position. Both intraperitoneal and onlay FTSGs showed increases in the amount of thick collagen bundles compared to internal controls. No correlation was seen between distribution of MMPs 1, 8 or 9 and distribution of collagen types I, III, IV or V.

CONCLUSION

This preclinical study shows that FTSGs in both intraperitoneal and onlay positions are possible application site options and, by extension, promising application site options for abdominal wall reinforcement in hernia surgery. Clinical studies in humans are required to confirm these findings.

Collagen Deposition and Inflammatory Response Associated with Macroporous Mesh Shrinkage in Incisional Hernia Repair: A Rat Model

Background: Mesh repair is the current recommendation for the treatment of incisional hernia; however, the best mesh has yet to be determined. The objective of this study was to compare the inflammatory response and collagen deposition in primary incisional hernia repair (P) and different macroporous mesh materials, including polypropylene with poliglecaprone (PP-PG), polyvinylidene fluoride (PVDF), and polyester (PE), using quantitative methods. Methods: Sixty male rats were divided into four groups. Anterior abdominal wall defects were created and either suture or mesh repair was done. Rats were euthanized on days 14, 90, and 180, and the gross findings were recorded. The inflammatory and collagen levels in the abdominal wall tissues were measured using enzyme-linked immunosorbent assay (ELISA). Results: The PE group demonstrated significant mesh shrinkage at 180 days. The extent of PE mesh shrinkage ranged from 22-42% (mean = 30.49%). At 14 days, the PVDF group had higher interleukin-6 (IL-6) levels than the PP-PG (P = .004) and PE groups (P = .019). At 90 days, the collagen type I (Col I) levels in the PE group were significantly lower than those in the others, and the collagen type I/III (Col I/III) ratios in the PE group were lower than those in the P group (P = .006). Conclusions: The persistently high IL-6 levels until 180 days and the decrease in Col I levels and Col I/III ratio at 90 days seem to predict mesh shrinkage at 180 days. The mesh induces high Col I levels, but those associated with low Col III levels should be preferred.

An estrogen-sensitive fibroblast population drives abdominal muscle fibrosis in an inguinal hernia mouse model

Greater than 25% of all men develop an inguinal hernia in their lifetime, and more than 20 million inguinal hernia repair surgeries are performed worldwide each year. The mechanisms causing abdominal muscle weakness, the formation of inguinal hernias, or their recurrence are largely unknown. We previously reported that excessively produced estrogen in the lower abdominal muscles (LAMs) triggers extensive LAM fibrosis, leading to hernia formation in a transgenic male mouse model expressing the human aromatase gene (Aromhum). To understand the cellular basis of estrogen-driven muscle fibrosis, we performed single-cell RNA sequencing on LAM tissue from Aromhum and wild-type littermates. We found a fibroblast-like cell group composed of 6 clusters, 2 of which were validated for their enrichment in Aromhum LAM tissue. One of the potentially novel hernia-associated fibroblast clusters in Aromhum was enriched for the estrogen receptor-α gene (Esr1hi). Esr1hi fibroblasts maximally expressed estrogen target genes and seemed to serve as the progenitors of another cluster expressing ECM-altering enzymes (Mmp3hi) and to upregulate expression of proinflammatory, profibrotic genes. The discovery of these 2 potentially novel and unique hernia-associated fibroblasts may lead to the development of novel treatments that can nonsurgically prevent or reverse inguinal hernias.

The Deep Fascia and its Role in Chronic Pain & Pathological Conditions: A Review

INTRODUCTION

The deep fascia is a three-dimensional continuum of connective tissue surrounding the bones, muscles, nerves and blood vessels throughout our body. Its importance in chronically debilitating conditions has recently been brought to light. This work investigates changes in these tissues in pathological settings.

MATERIALS AND METHODS

A state-of-the-art review was conducted in PubMed and Google Scholar following a two-stage process. A first search was performed to identify main types of deep fasciae. A second search was performed to identify studies considering a deep fascia, common pathologies of this deep fascia and the associated alterations in tissue anatomy.

RESULTS

We find that five main deep fasciae pathologies are chronic low back pain, chronic neck pain, Dupuytren's disease, plantar fasciitis and iliotibial band syndrome. The corresponding fasciae are respectively the thoracolumbar fascia, the cervical fascia, the palmar fascia, the plantar fascia and the iliotibial tract. Pathological fascia is characterized by increased tissue stiffness along with alterations in myofibroblast activity and the extra-cellular matrix, both in terms of collagen and Matrix Metalloproteases (MMP) levels. Innervation changes such as increased density and sensitization of nociceptive nerve fibers are observed. Additionally, markers of inflammation such as pro-inflammatory cytokines and immune cells are documented. Pain originating from the deep fascia likely results from a combination of increased nerve density, sensitization and chronic nociceptive stimulation, whether physical or chemical.

CONCLUSIONS

The pathological fascia is characterized by changes in innervation, immunology and tissue contracture. Further investigation is required to best benefit both research opportunities and patient care.

Histologic changes during healing with autologous fascia lata graft after superior capsule reconstruction in rabbit model

BACKGROUND

Superior capsule reconstruction (SCR) has been developed to improve shoulder function and relieve pain in the treatment of irreparable rotator cuff tears. Previous studies have reported that graft healing can enhance favorable outcomes after SCR. On the other hand, graft tears often lead to less desirable outcomes and sometimes require additional surgical procedures. However, the healing process underlying this remains unclear. In this study, we aimed to investigate histologic changes occurring during the healing process associated with autologous fascia lata graft after SCR in vivo. We hypothesized that (1) autologous fascia lata graft can regenerate the fibrocartilaginous insertion into both the greater tuberosity and superior glenoid and (2) the midsubstance of the grafted fascia gradually remodels into tendon- and/or ligament-like tissue after SCR.

METHODS

Irreparable supraspinatus tendon defects were created in 24 mature Japanese white rabbits (age, 6 months; mean weight, 3.2 kg). Four weeks after creation of the defects, the right shoulders were subjected to SCR using autologous fascia lata grafts. The left shoulders were left untreated. Samples from the shoulders were harvested at 4, 8, 12, and 16 weeks after surgery to undergo histologic and immunohistochemical examinations.

RESULTS

Macroscopically, we did not observe graft tears after SCR in our experiments. Histologically, the number of chondrocyte-like cells gradually increased, and the extracellular matrices around those cells contained glycosaminoglycan at the fascia-bone junction after SCR. The unmineralized fibrocartilage, mineralized fibrocartilage, and tidemark were observed 16 weeks after SCR. The distribution of type II collagen presented a pattern similar to that of a normal tendon and ligament insertion. The cells and collagen fiber gradually oriented parallelly to the long axis in the midsubstance of the grafted fascia lata. Additionally, type III collagen was replaced with type I collagen in the midsubstance of the grafted fascia lata after SCR.

CONCLUSIONS

SCR using fascia lata autograft regenerated the fibrocartilaginous insertion at both the greater tuberosity and superior glenoid. The midsubstance of the grafted fascia gradually remodeled into tendon- and/or ligament-like tissue. These results suggest that the fascia lata autograft has the capacity for graft-to-bone healing and remodeling after SCR.

Distinctive roles of fibrillar collagen I and collagen III in mediating fibroblast-matrix interaction: A nanoscopic study

One major goal in tissue engineering is to create functional materials, mimicking scaffolds in native tissues, to modulate cell function for tissue repair. Collagen is the most abundant structural protein in human body. Though collagen I (COLI) and collagen III (COLIII) are the predominant collagen types in connective tissues and they form stable hybrid fibrils at varied ratios, cell responses to the hybrid matrices are underinvestigated. In this work, we aim to explicate the distinctive roles of COLI and COLIII in fibroblast activation. Unidirectionally aligned COLI, COLIII and COLI-COLIII hybrid nanofibrils were generated via epitaxial growth of collagen on mica. AFM analyses revealed that, with the increase of COLI/COLIII ratio, the fibril width and stiffness increased and the binding affinity of cells to the matrix decreased. A hybrid matrix was found to activate fibroblasts the most effectively, characterized by extensive cell polarization with rigid stress fiber bundles and high α-SMA expression, and by the highest-level of collagen synthesis. It is ascribed to the fine balance between biochemical and biophysical cues achieved on the hybrid matrix. Thus, matrices of aligned COLI-COLIII hybrid fibrils and their derived multifunctional composites can be good candidates of implantation scaffolds for tissue regeneration.

Long-term Comparison of Recurrence Rates Between Different Lightweight and Heavyweight Meshes in Open Anterior Mesh Inguinal Hernia Repair: A Nationwide Population-based Register Study

OBJECTIVE

To compare the reoperation rate for recurrence of different lightweight to heavyweight meshes after an open anterior mesh (OAM) inguinal hernia repair.

SUMMARY BACKGROUND DATA

Lightweight meshes have shown benefits compared with heavyweight meshes in terms of accelerated recovery after surgery with less postoperative pain. The use of such meshes may, however, be associated with an increase in hernia recurrence. Studies of large cohorts with long-term follow-up regarding recurrence are lacking.

METHODS

All OAM groin hernia repairs registered in The Swedish Hernia Register between January 1, 2005 and December 31, 2013 were eligible. Follow-up time was until June 30, 2016. Four groups of meshes were included: polypropylene (PP) heavyweight meshes >50 g/m2 (HWM), regular lightweight PP meshes <50 g/m2 (regular LWM-PP), lightweight PP mesh with absorbable poliglecaprone-25(LWM-PP/PGC), or polyglactin-910(LWM-PP/PG). Primary endpoint was reoperation for recurrence.

RESULTS

76,495 OAM inguinal hernia repairs in male patients were included for statistical analysis. 1676 repairs were reoperated for recurrence. Multivariate analysis demonstrated no significant difference of risk for recurrence between HWM and regular LWM-PP (HR 1.12, P = 0.13). LWM-PP/PGC (HR 1.42, P < 0.001) and LWM-PP/PG (HR 2.05, P < 0.001) resulted in a significant increased risk compared with HWM. Larger hernia defects, direct hernias, and recurrent hernias were associated with an increased risk of reoperation for recurrence.

CONCLUSIONS

Although lightweight meshes with partially absorbable component resulted in an increased risk of recurrence, there was no difference between regular LWM-PP and HWM. Considering that regular LWM-PP has less associated side effects there are no benefits of using HWM in OAM inguinal hernia repair.

Incisional Hernia After Liver Transplantation: Analysis of Tailored Open Mesh Repair

Objective

Incisional hernia is a frequent complication post liver transplantation (LT). The aim of this study was to compare divergent approaches to open abdominal wall repair post-LT.

Summary of background data

After liver transplantation (LT) via Mercedes incision (MSI) we observed an incidence of incisional hernia between 5% and 34%. Conventional repair consists of reopening the whole incision and reinforcement of the whole fascia using a mesh plastic in sublay position. This retrospective analysis compares open mesh repair with complete reinforcement of the Mercedes incision and open mesh repair of solely the abdominal wall defect.

Methods

Between 2010 and 2015, 218 orthotopic liver transplantations (LT) were performed at our institution, and 25 (11.5%) of those patients required an incisional hernia repair post-LT. One group received a local hernia repair (n = 15) while the other group obtained a reconstruction of the whole MSI (n = 10). We analyzed the preoperative status, causative factors for incisional hernia, operative details, and long-term outcome of these patients.

Results

Analyzing preoperative details no significant differences were found between the 2 groups. The mean time post-LT at which the abdominal wall defect appeared was 18 ± 12 months. The mean follow-up time after abdominal wall repair was 15 (11–19) months. Additionally, 1 (4%) patient developed a hernia recurrence without statistic significant difference between the 2 groups (P = 0.400).

Conclusion

Local mesh reinforcement seems to be feasible and safe in incisional hernia patients after Mercedes incision due to liver transplantation.

Effectiveness of fascial manipulation on pain and disability in musculoskeletal conditions. A systematic review

OBJECTIVE

To review the effectiveness of Stecco's fascial manipulation technique in patients with musculoskeletal pain.

DESIGN

Systematic review of interventional studies.

METHODS

A systematic search of literatures was performed in the electronic databases: PubMed, Cochrane, Scopus, ScienceDirect, and Ovid from January 2005 to December 2019. Studies were included if they were followed stecco's fascial manipulation as an intervention for the musculoskeletal conditions. RCTs and Non RCTs both were included in this review.

RESULTS

Thirteen studies met the eligibility criteria [RCTs-8, Pre-Post studies-3, Case reports-2]. Stecco's FM technique was followed in all the included studies. Five studies applied FM technique alone, while two studies added exercise along with FM and one study substitute session with manual therapy.

CONCLUSION

This systematic review reported low to moderate quality evidence for the effect of FM in improving pain and disability in subjects with musculoskeletal pain conditions, when it is carried out as described in the Stecco's concept.

Incisional hernia after liver transplantation: mesh-based repair and what else?

Purpose

Incisional hernia (IH) is not uncommon after liver transplantation (LT). We investigated the long-term outcome of mesh-based hernia repair using an inlay-onlay technique.

Methods

Our analysis was based on a prospective collected database of all LT recipients from our hospital over a period of 15 years. We analyzed clinical data including the period between LT and hernia development, the size and localization of the hernia, the length of in-hospital stay, immunosuppression, and postoperative morbidity, as well as follow-up data. The median follow-up period was 120 (range 12–200) months.

Results

Among a total of 220 patients who underwent a collective 239 LTs, 29 (13%) were found to have an IH after a median period of 27.5 months (range 3–96 months). There were 12 (41%) men and 17 (59%) women, with a median age of 51 years. The median size of the IH was 13 cm (range 2–30 cm) and the median in-hospital stay was 6 days. Mild postoperative complications developed in seven patients, including two onlay mesh infections. One patient (3.4%) suffered recurrence.

Conclusion

Mesh-based hernia repair using the inlay/onlay technique represents an effective and safe method for patients with an IH after LT, without additional risk from continuous immunosuppression.

Hernia Repair Strength Enhanced With Antioxidants

BACKGROUND

Incisional hernia is one of the most common complications of abdominal surgery, and repairs are associated with significant recurrence rates. Mesh repairs are associated with the best outcomes, but failures are not uncommon. Doxycycline has been demonstrated to enhance mesh hernia repair outcomes with associated increases in collagen deposition and improved tensiometric strength. This study compares the outcomes of incisional hernia repair with doxycycline administration and the antioxidant tempol.

MATERIALS AND METHODS

Twenty-eight male Sprague Dawley rats underwent a midline hernia creation and an intraabdominal polypropylene mesh repair. The animals were administered saline, doxycycline, tempol, or both, daily for 8 wk. The abdominal wall was harvested at 8 wk and tensiometric strength and biochemical analysis was performed.

RESULTS

The tensiometric strength of the repair was increased in all experimental groups. Collagen type 1 deposition was increased, and collagen type 3 deposition was decreased in each of the experimental groups relative to control. There was no difference in MMP-2 and MMP-9 levels between control and experimental groups.

CONCLUSIONS

The hernia repair strength is equally enhanced with the administration of doxycycline or tempol. Dual therapy provided no benefit over treatment with either single agent. All treatment groups had an increase in collagen type 1:3 ratios, but the mechanism is not well understood. The benefits of antioxidant treatment following hernia repair are similar to treatment with doxycycline. Given the high frequency of incisional hernia repair failures, this study has implications for improving outcomes following ventral hernia repair through the use of either doxycycline or antioxidant therapy.

[Preventative repair of postoperative ventral hernia considering the markers of connective tissue dysplasia]

OBJECTIVE

To define the indication for preventive mesh implantation in patients scheduled for laparotomy.

MATERIAL AND METHODS

There were 108 patients divided into the control (52 patients without anterior abdominal wall hernia) and the main (56 patients with ventral hernia) groups.

RESULTS

Predominance of collagen type III over type I was observed in patients older 60 years in the main group. The maximum ratio of collagen types I and III was 1.4 in the main group. The minimum number of inter-fiber spaces (n=5) was noted in patients aged 30-40 years. The maximum density of connective tissue was 250 pixels per inch.

CONCLUSION

Analysis of connective tissue structures revealed some important age-related features and markers of connective tissue dysplasia in the main group. An indication for preventive mesh implantation in patients scheduled for laparotomy was determined.

Velvet antler polypeptide partially rescue facet joint osteoarthritis-like phenotype in adult β-catenin conditional activation mice

BACKGROUND

Wnt/β-catenin signaling pathway is closely related to osteoarthritis. In our preliminary study, β-catenin conditional activation (cAct) mice that specifically over-express β-catenin gene in cartilage chondrocyte exhibits osteoarthritis-like phenotype in the lumbar disc and knee joint. Therefore, we used the mice to model FJ-OA and test the potential curative effect of Velvet Antler Polypeptide (VAP) on this mice model.

METHODS

We tested the effect of VAP on β-catenin conditional activation mice, and used Cre negative littermates as controls. Micro-CT, histology and histomorphometry analysis were performed to evaluate the curative effect of VAP on mice facet joint-like phenotype. Expression of β-catenin and collagen II was detected by immunohistochemistry (IHC) and western-blot., MMP13, ADAMTS4 and ADAMTS5 was detected by immunofluorescence (IF). RT-PCR analysis was preformed to detect mRNA expression of cartilage degrading enzymes, such as MMP13, ADAMTS4 and ADAMTS5.

RESULTS

Results of micro-CT (μCT) analysis showed that VAP could partially reverse lumbar disc osteophyte formation observed in β-catenin(ex3)^Col2ER mice. Histology data revealed VAP partially improved facet joint cartilage tissue invades. Histomorphometry analysis showed an increase in total cartilage area after VAP treatment. IHC show that VAP reduced β-catenin protein levels and moderately up-regulated collagen II protein levels. RT-PCR and IF data showed that VAP down-regulated the expression of extracellular matrix synthesis (ECM) degradation enzymes MMP13, ADAMTS4 and ADAMTS5.

CONCLUSION

Taken together, VAP may modulate ECM by inhibits MMP13, ADAMTS4 and ADAMTS5 via Wnt /β-catenin signaling pathway. Velvet Antler Polypeptide may be a potential medicine for FJ-OA.

Atrophic acne scar: a process from altered metabolism of elastic fibres and collagen fibres based on transforming growth factor-β1 signalling

BACKGROUND

Atrophic acne scar, a persistent sequela from acne, is undesirably troubling to many patients due to its cosmetic and psychosocial aspects. Although there have been some reports emphasizing the role of early inflammatory responses in atrophic acne scarring, evolving perspectives on the detailed pathogenic processes are promptly needed.

OBJECTIVES

Examining the histological, immunological and molecular changes in early acne lesions susceptible to atrophic scarring can provide new insights to understand the pathophysiology of atrophic acne scar.

METHODS

We experimentally validated several early fundamental hallmarks accounting for the transition of early acne lesions to atrophic scars by comparing molecular profiles of skin and acne lesions between patients who were prone to scar (APS) or not (ANS).

RESULTS

In APS, compared with ANS, devastating degradation of elastic fibres and collagen fibres occurred in the dermis, followed by their incomplete recovery. Abnormally excessive inflammation mediated by innate immunity with T helper 17 and T helper 1 cells was observed. Epidermal proliferation was significantly diminished. Transforming growth factor (TGF)-β1 was drastically elevated in APS, suggesting that aberrant TGF-β1 signalling is an underlying modulator of all of these pathological processes.

CONCLUSIONS

These results may provide a basis for understanding the pathogenesis of atrophic acne scarring. Reduction of excessive inflammation and TGF-β1 signalling in early acne lesions is expected to facilitate the protection of normal extracellular matrix metabolism and ultimately the prevention of atrophic scar formation. What's already known about this topic? The dermis of atrophic acne scars shows alteration of extracellular matrix components such as collagen fibres. Inflammation in acne lesions is associated with the development of acne scars. What does this study add? Abnormalities in the metabolism of collagen fibres and elastic fibres were observed in the early developmental stages of acne lesions that were progressing into atrophic scars. Exacerbated inflammation and aberrant epidermal proliferation by increased transforming growth factor (TGF)-β1 signalling may affect the abnormal extracellular matrix metabolism. What is the translational message? Abnormal changes in elastic fibres and collagen fibres are found in the early developmental process of acne in patients who are prone to atrophic scarring. An early treatment regimen strongly inhibiting inflammation and TGF-β1 signalling to help the normal recovery of the extracellular matrix components is required to prevent atrophic scarring.

Novel understanding of high mobility group box-1 in the immunopathogenesis of incisional hernias

Introduction: Incisional hernias (IH) arise as a complication of patients undergoing laparotomy. Current literature has assessed the role of extracellular matrix (ECM) disorganization, alterations in type I and type III collagen, matrix metalloproteinases, and tissue inhibitors of metalloproteases on IH. However, there is limited information on the underlying molecular mechanisms that lead to ECM disorganization. Areas covered: We critically reviewed the literature surrounding IH and ECM disorganization and offer a novel pathway that may be the underlying mechanism resulting in ECM disorganization and the immunopathogenesis of IH. Expert opinion: High mobility group box-1 (HMGB-1), a damage-associated molecular pattern, plays an important role in the sterile inflammatory pathway and has been linked to ECM disorganization and the triggering of the NLRP3 inflammasome. Further research to investigate the role of HMGB-1 in the molecular pathogenesis of IH would be critical in identifying novel therapeutic targets in the management of IH formation.

Incidence of and risk factors for incisional hernia after closure of temporary ileostomy for colorectal malignancy

PURPOSE

Incisional hernia is a major complication after stoma closure and can cause uncomfortable symptoms. In this study, we evaluated the risk factors for hernia formation with the aim of reducing the incidence of incisional hernia.

METHODS

A total of 134 oncology patients underwent closure of a temporary loop ileostomy between May 2004 and December 2013. The incidence of incisional hernia was determined by routine follow-up computed tomography scanning every 6 months. The relationships between patients' characteristics, including age, sex, obesity, diabetes mellitus, surgical site infection, chronic obstructive pulmonary disease, hypertension, hypoalbuminemia, smoking, and presence of a midline hernia and the occurrence of incisional hernia were retrospectively evaluated.

RESULTS

The median follow-up time was 47 months (range 8-130). Hernias occurred in 23.9% of patients (32/134). The median time to detection of hernias was 8 months (range 2-39). The Chi-squared test revealed significant differences in obesity (P = 0.0003), hypertension (P = 0.0057), and incisional hernia history (P = 0.0000) between patients with and without incisional hernia. Multivariable analysis and univariate analysis revealed that hypertension and the presence of midline incisional hernia were risk factors for incisional hernia.

CONCLUSIONS

Hypertension and the presence of a midline incisional hernia were the major risk factors for incisional hernia after loop ileostomy closure. These risk factors can be addressed before planning surgery.

The incidence of incisional hernia after aortic aneurysm is not higher than after benign colorectal interventions: A retrospective control-matched cohort study

Background

Abdominal aortic aneurysms (AAA) have most probably an inflammatory origin, whereby the elastica is the layer actually involved. In the past, collagen weackness was supposed to be the shared cause of both, AAA and incisional hernias. Since the development of new techniques of closure of the abdominal wall over the last decade, collagen deficency seems to play only a secondary etiologic role.

Objectives

The aim of the study was to investigate whether the incidence of incisional hernia following laparotomy due to AAA differs from that of colorectal interventions.

Material and methods

This was a retrospective control matched cohort study. After screening of 403 patients with colorectal interventions and 96 patients with AAA, 27 and 72 patients, respectively were included. The match criteria for inclusion of patients with colorectal interventions were: age, benign underlying disease and median xiphopubic laparotomy. The primary endpoint was the incidence of an incisional hernia. The secondary endpoints were the risk profile, length of stay in the intensive care unit and postoperative complications. Data analysis was carried in the consecutive collective from 2006 to 2008.

Results

In the group with AAA the mean follow-up was 34.5±18.1 months and in the group with colorectal interventions 35.7±21.4 months. The incidence of incisional hernias showed no significant differences between the two groups. In the AAA group 10 patients (13.8%) developed an incisional hernia in contrast to 7 patients in the colorectal intervention group (25.9%).

Conclusions

In our collective patients with AAA did not show an increased incidence of incisional hernia in comparison to patients with colorectal interventions with comparable size of the laparotomy access and age. The quality of closure of the abdominal wall seems to be an important factor for the prevention of incisional hernia.

Autologous Bone Marrow Mesenchymal Stem Cells Improve the Quality and Stability of Vascularized Flap Surgery of Irradiated Skin in Pigs

Cutaneous radiation syndrome has severe long-term health consequences. Because it causes an unpredictable course of inflammatory waves, conventional surgical treatment is ineffective and often leads to a fibronecrotic process. Data about the long-term stability of healed wounds, with neither inflammation nor resumption of fibrosis, are lacking. In this study, we investigated the effect of injections of local autologous bone marrow-derived mesenchymal stromal cells (BM-MSCs), combined with plastic surgery for skin necrosis, in a large-animal model. Three months after irradiation overexposure to the rump, minipigs were divided into three groups: one group treated by simple excision of the necrotic tissue, the second by vascularized-flap surgery, and the third by vascularized-flap surgery and local autologous BM-MSC injections. Three additional injections of the BM-MSCs were performed weekly for 3 weeks. The quality of cutaneous wound healing was examined 1 year post-treatment. The necrotic tissue excision induced a pathologic scar characterized by myofibroblasts, excessive collagen-1 deposits, and inadequate vascular density. The vascularized-flap surgery alone was accompanied by inadequate production of extracellular matrix (ECM) proteins (decorin, fibronectin); the low col1/col3 ratio, associated with persistent inflammatory nodules, and the loss of vascularization both attested to continued immaturity of the ECM. BM-MSC therapy combined with vascularized-flap surgery provided mature wound healing characterized by a col1/col3 ratio and decorin and fibronectin expression that were all similar to that of nonirradiated skin, with no inflammation, and vascular stability. In this preclinical model, vascularized flap surgery successfully and lastingly remodeled irradiated skin only when combined with BM-MSC therapy. Stem Cells Translational Medicine 2018:569-582.

Activity of metalloproteinases and adiponectin in obese patients-a possible factor of incisional hernias after bariatric procedures

PURPOSE

Metalloproteinases are a key component of the pathogenesis of abdominal hernias. Obesity is considered a risk factor in herniogenesis and hernia recurrence. The aim of this study was to evaluate the serum concentrations of metalloproteinase-2 (MMP-2), MMP-9, MMP-13, and adiponectin in morbidly obese and non-overweight controls.

MATERIALS AND METHODS

The participants were recruited from among patients undergoing bariatric and non-bariatric surgery and divided into two groups: I (body mass index (BMI)≥35 kg/m², n=40) and II (BMI<25 kg/m², n=30). Serum concentrations of MMP-2, MMP-9, MMP-13, and adiponectin were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

A statistically significant difference between groups was observed for MMP-2 concentration. The median MMP-9 concentration was higher in the obese group, but the difference was not statistically significant. Median MMP-13 concentrations did not differ between groups. Serum adiponectin concentration was insignificantly higher in the non-obese group.

CONCLUSIONS

The elevated serum MMP-2 and MMP-9 concentrations in obese individuals may be related to the higher incidence of incisional hernias in this population.

Collagenopathies-Implications for Abdominal Wall Reconstruction: A Systematic Review

Background:

The etiology of hernia formation is strongly debated and includes mechanical strain, prior surgical intervention, abnormal embryologic development, and increased intraabdominal pressure. Although the most common inciting cause in ventral hernias is previous abdominal surgery, many other factors contribute. We explore this etiology through an examination of the current literature and existing evidence on patients with collagen vascular diseases, such as Ehlers–Danlos syndrome.

Methods:

A systematic review of the published literature was performed of all available Spanish and English language PubMed and Cochrane articles containing the key words “collagenopathies,” “collagenopathy,” “Ehlers-Danlos,” “ventral hernia,” and “hernia.”

Results:

Three hundred fifty-two articles were identified in the preliminary search. After review, 61 articles were included in the final review.

Conclusions:

Multiple authors suggest a qualitative or quantitative defect in collagen formation as a common factor in hernia formation. High-level clinical data clearly linking collagenopathies and hernia formation are lacking. However, a trend in pathologic studies suggests a link between abnormal collagen production and/or processing that is likely associated with hernia development.

Discovery of novel plasma proteins as biomarkers for the development of incisional hernias after midline incision in patients with colorectal cancer: The ColoCare study

BACKGROUND

Ventral incisional hernia is the most common long-term complication after an abdominal operation. Among newly diagnosed colorectal cancer patients, we screened the preoperative plasma proteome to explore predictive markers for the development of an incisional hernia.

METHODS

We utilized preoperative plasma samples of 72 newly diagnosed colorectal cancer patients who underwent midline incision for tumor resection between 2010 and 2013. A total of 21 patients with incisional hernia occurrence were matched with 51 patients with at least 18 months follow-up without an incisional hernia by sex, age, and body mass index. To assess predictive markers of incisional hernia risk, we screened the plasma proteome for >2,000 distinct proteins using a well-validated antibody microarray test. Paired t tests were used to compare protein levels between cases and controls. A gene-set-enrichment analysis (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes) was applied to test for differences in signaling pathways between the 2 groups.

RESULTS

The proteome screen identified 25 proteins that showed elevated or reduced plasma levels in the hernia group compared to the control group (nominal P values < .05). Several proteins were in pathways associated with wound healing (CCL21, SHBG, BRF2) or cell adhesion (PCDH15, CDH3, EPCAM).

CONCLUSION

Our study shows that there are multiple individual and groups of plasma proteins that could feasibly predict the personal hernia risk prior to undergoing an operation. Further investigations in larger, independent sample sets are warranted to replicate findings and validate clinical utility of potential biomarkers. After validation, such a biomarker could be incorporated into a multifactorial risk model to guide clinical decision-making.

Surgical Treatment of Paraesophageal Hernias: A Review

The management of paraesophageal hernia (PEH) can be challenging due to the lack of consensus regarding indications and principles of operative treatment. In addition, data about the pathophysiology of the hernias are scant. Therefore, the goal of this review is to shed light and describe the classification, pathophysiology, clinical presentation, and indications for treatment of PEHs, and provide an overview of the surgical management and a description of the technical principles of the repair.

Giant ventral hernia-relationship between abdominal wall muscle strength and hernia area

Background

Symptoms arising from giant ventral hernia have been considered to be related to weakening of the abdominal muscles. The aim of this study was to investigate the relationship between the area of the abdominal wall defect and abdominal wall muscle strength measured by the validated BioDex system together with a back/abdominal unit.

Methods

Fifty-two patients with giant ventral hernia (>10 cm wide) underwent CT scan, clinical measurement of hernia size and BioDex measurement of muscle strength prior to surgery. The areas of the hernia derived from CT scan and from clinical measurement were compared with BioDex forces in the modalities extension, flexion and isometric contraction. The Spearman rank test was used to calculate correlations between area, BMI, gender, age, and muscle strength.

Result

The hernia area calculated from clinical measurements correlated to abdominal muscle strength measured with the Biodex for all modalities (p-values 0.015–0.036), whereas no correlation was seen with the area calculated by CT scan. No relationship was seen between BMI, gender, age and the area of the hernia.

Discussion

The inverse correlation between BioDex abdominal muscle strength and clinically assessed hernia area, seen in all modalities, was so robust that it seems safe to conclude that the area of the hernia is an important determinant of the degree of loss of abdominal muscle strength. Results using hernia area calculated from the CT scan showed no such correlation and this would seem to concur with the results from a previous study by our group on patients with abdominal rectus diastasis. In that study, defect size assessed clinically, but not that measured by CT scan, was in agreement with the size of the diastasis measured intra-operatively.

The point at which the area of a hernia begins to correlate with loss of abdominal wall muscle strength remains unknown since this study only included giant ventral hernias.

Abdominal wall hernias-A local manifestation of systemically impaired quality of the extracellular matrix

BACKGROUND

Throughout life, inguinal hernia develops in approximately every fourth man, some of whom develop multiple hernias. If patients at risk of developing multiple hernias could be identified by a serologic biomarker, treatment might be able to be tailored and improved. Evidence suggests that abdominal wall hernia formation is associated with altered collagen metabolism. The aim of this study was to evaluate biomarkers for type IV and V collagen turnover in patients with multiple hernias and control subjects without hernia.

METHODS

Venous blood was collected from 88 men (mean age, 62 years) with a history of more than 3 hernia repairs and 86, age-matched men without hernias. Biomarkers for synthesis of collagen type IV (P4NP) and type V (P5CP) as well as breakdown (C4M and C5M) were measured in serum by validated, solid-phase, competitive assays. Collagen turnover was indicated by the ratio between the biomarker for synthesis and breakdown.

RESULTS

Type IV collagen turnover was 1.4-fold increased in patients with multiple hernias compared to control subjects (P < .001), whereas type V collagen turnover was 1.7-fold decreased (P < .001). Diagnostic power of P5CP was 0.83 (95%C.I.:0.77-0.89), P < .001.

CONCLUSION

Patients with multiple hernias exhibit increased turnover of type IV collagen and a decreased turnover of type V collagen, demonstrating systemically altered collagen turnover. Biomarkers for type V collagen turnover may be used to identify patients at risk for or with multiple hernias.

Short-term results of a randomized controlled trial comparing primary suture with primary glued mesh augmentation to prevent incisional hernia

BACKGROUND

Incisional hernia is one of the most frequent postoperative complications after abdominal surgery. Patients with an abdominal aortic aneurysm and patients with a body mass index of 27 or higher have an increased risk to develop incisional hernia. Primary mesh augmentation is a method in which the abdominal wall is strengthened to reduce incisional hernia incidence. This study focused on the short-term results of the PRImary Mesh Closure of Abdominal Midline Wounds trial, a multicenter double blind randomized controlled trial.

METHODS

Between 2009 and 2012 patients were included if they were operated via midline laparotomy, and had an abdominal aortic aneurysm or a body mass index of 27 or higher. Patients were randomly assigned to either receive primary suture, onlay mesh augmentation (OMA), or sublay mesh augmentation.

RESULTS

Outcomes represent results after 1-month follow-up. A total of 480 patients were randomized. During analysis, significantly (P = 0.002) more seromas were detected after OMA (n = 34, 18.1%) compared with primary suture (n = 5, 4.7%) and sublay mesh augmentation (n = 13, 7%). No differences were discovered in any of the other outcomes such as surgical site infection, hematoma, reintervention, or readmission. Multivariable analysis revealed an increase in seroma formation after OMA with an odds ratio of 4.3 (P = 0.004) compared with primary suture and an odds ratio of 2.9 (P = 0.003) compared with sublay mesh augmentation.

CONCLUSIONS

On the basis of these short-term results, primary mesh augmentation can be considered a safe procedure with only an increase in seroma formation after OMA, but without an increased risk of surgical site infection.

Remodeling characteristics and collagen distribution in biological scaffold materials explanted from human subjects after abdominal soft tissue reconstruction: an analysis of scaffold remodeling characteristics by patient risk factors and surgical site classifications

OBJECTIVE

The study purpose was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of biologic meshes biopsied from abdominal soft tissue repair sites in the first attempt to generate a multivariable risk-prediction model of nonconstructive remodeling.

BACKGROUND

Host characteristics and surgical site assessments may predict remodeling degree for biologic meshes used to reinforce abdominal tissue repair sites.

METHODS

Biologic meshes were biopsied from the abdominal tissue repair sites of n = 40 patients during an abdominal reexploration, stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell types, cell infiltration, extracellular matrix deposition, scaffold degradation, fibrous encapsulation, and neovascularization) and a mean composite score. Biopsies were stained with Sirius Red and Fast Green and analyzed to determine the collagen I:III ratio. On the basis of univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using P ≤ 0.200.

RESULTS

The model selection process for cell infiltration score yielded 2 variables: age at mesh implantation and mesh classification (C statistic = 0.989). For the mean composite score, the model selection process yielded 2 variables: age at mesh implantation and mesh classification (r = 0.449).

CONCLUSIONS

These preliminary results constitute the first steps in generating a risk-prediction model that predicts the patients and clinical circumstances most likely to experience nonconstructive remodeling of abdominal tissue repair sites with biologic mesh reinforcement.

Wound healing in acutely injured fascia

Fascial healing following acute injury, such as that occurring during surgical procedures, is defined functionally. For example, failure of fascial healing following celiotomy is only identified when incisional hernias are diagnosed. Such hernias incur billions of dollars per year in medical costs. Despite the importance of fascial healing, there is a paucity of data regarding the quality such healing. In clinical settings, the quantification of fascial wound healing is limited to a binary state: either there is no clinically apparent functional deficit and full fascia healing is assumed, or an incisional hernia or other functional failure is visible and the fascia did not heal. There are no clinical methods to isolate and functionally test fascia in patients. Recent studies have revealed unexpected findings regarding the recovery of tensile strength, specific surgical methods that optimize fascial healing, and the potential impact of biological pharmaceuticals in eliminating fascial healing failure. However, much remains unknown about the biology of fascial healing.

Therapeutic potential of gingival fibroblasts for cutaneous radiation syndrome: comparison to bone marrow-mesenchymal stem cell grafts

Mesenchymal stem cell (MSC) therapy has recently been investigated as a potential treatment for cutaneous radiation burns. We tested the hypothesis that injection of local gingival fibroblasts (GFs) would promote healing of radiation burn lesions and compared results with those for MSC transplantation. Human clinical- grade GFs or bone marrow-derived MSCs were intradermally injected into mice 21 days after local leg irradiation. Immunostaining and real-time PCR analysis were used to assess the effects of each treatment on extracellular matrix remodeling and inflammation in skin on days 28 and 50 postirradiation. GFs induced the early development of thick, fully regenerated epidermis, skin appendages, and hair follicles, earlier than MSCs did. The acceleration of wound healing by GFs involved rearrangement of the deposited collagen, modification of the Col/MMP/TIMP balance, and modulation of the expression and localization of tenascin-C and of the expression of growth factors (VEGF, EGF, and FGF7). As MSC treatment did, GF injection decreased the irradiation-induced inflammatory response and switched the differentiation of macrophages toward an M2-like phenotype, characterized by CD163(+) macrophage infiltration and strong expression of arginase-1. These findings indicate that GFs are an attractive target for regenerative medicine, for easier to collect, can grow in culture, and promote cutaneous wound healing in irradiation burn lesions.

Remodeling characteristics and collagen distribution in synthetic mesh materials explanted from human subjects after abdominal wall reconstruction: an analysis of remodeling characteristics by patient risk factors and surgical site classifications

BACKGROUND

The purpose of this study was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of synthetic meshes biopsied from their abdominal wall repair sites in the first attempt to generate a multivariable risk prediction model of non-constructive remodeling.

METHODS

Biopsies of the synthetic meshes were obtained from the abdominal wall repair sites of 51 patients during a subsequent abdominal re-exploration. Biopsies were stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell infiltration, cell types, extracellular matrix deposition, inflammation, fibrous encapsulation, and neovascularization) and a mean composite score (CR). Biopsies were also stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a threshold p value of ≤0.200.

RESULTS

The model selection process for the extracellular matrix score yielded two variables: subject age at time of mesh implantation, and mesh classification (c-statistic = 0.842). For CR score, the model selection process yielded two variables: subject age at time of mesh implantation and mesh classification (r (2) = 0.464). The model selection process for the collagen III area yielded a model with two variables: subject body mass index at time of mesh explantation and pack-year history (r (2) = 0.244).

CONCLUSION

Host characteristics and surgical site assessments may predict degree of remodeling for synthetic meshes used to reinforce abdominal wall repair sites. These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances for which non-constructive remodeling of an abdominal wall repair site with synthetic mesh reinforcement is most likely to occur.

Measurement of hydroxyproline and nitric oxide, and comparison of sac fluid acidity in different inguinal pathologies

PURPOSE

To compare hydroxyproline and nitric oxide levels, and fluid acidity between sac tissues from inguinal hernia, hydrocele and undescended testis patients.

MATERIAL AND METHOD

Thirty patients were in the inguinal hernia group, 11 patients in the hydrocele group and 5 patients in the undescended testis with inguinal hernia group. Intrasaccular fluid acidity, and nitric oxide and hydroxyproline levels in sac tissues were measured and analyzed statistically between groups.

RESULTS

Intrasaccular fluid could be obtained from 24 inguinal hernia and 6 hydrocele patients. Acidity level (pH) was 7.5 ± 0.74 in the hernia group and 7.86 ± 0.63 in the hydrocele group (p < 0.05). All patients in the three groups were evaluated for nitric oxide and hydroxyproline. Results for hydroxyproline (mg/g dry tissue)/nitric oxide (nmol/g wet tissue) were 3.53 ± 0.54/2.02 ± 0.39 for inguinal hernia, 2.89 ± 0.9/1.92 ± 1.05 for hydrocele and 3.02 ± 1.23/2.86 ± 1.09 for undescended testis group (p > 0.05).

CONCLUSION

Hydroxyproline and nitric oxide pathways do not seem to be responsible for the different characteristics of inguinal diseases. However, differences in the acidity of sac fluid may be evidence of the different mechanisms of hernia and hydrocele formation.

Circulating levels of matrix metalloproteinases and tissue inhibitors of metalloproteinases in patients with incisional hernia

Incisional hernia formation is a common complication to laparotomy and possibly associated with alterations in connective tissue metabolism. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are closely involved in the metabolism of the extracellular matrix. Our aim was to study serum levels of multiple MMPs and TIMPs in patients with and without incisional hernia. Out of 305 patients who underwent laparotomy, 79 (25.9%) developed incisional hernia over a median follow-up period of 3.7 years. Pooled sera from a subset (n = 72) of these patients were screened for MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12, MMP-13, TIMP-1, TIMP-2, and TIMP-4 using a multiplex sandwich fluorescent immunoassay supplemented with gelatin zymography. The screening indicated differences in serum MMP-9 and TIMP-1 levels. Consequently, MMP-9 and TIMP-1 levels were measured in serum in the whole patient cohort with enzyme-linked immunosorbent assay. There were no significant differences in either MMP-9 (p = 0.411) or TIMP-1 (p = 0.679) levels between hernia and hernia-free patients. MMP-9 was significantly increased in smokers compared with nonsmokers (p = 0.016). In conclusion, a possible involvement of MMPs and TIMPs in the pathogenesis of incisional hernia formation was not reflected systemically.

Direct and recurrent inguinal hernias are associated with ventral hernia repair: a database study

BACKGROUND

A systemically altered connective tissue metabolism has been demonstrated in patients with abdominal wall hernias. The most pronounced connective tissue changes are found in patients with direct or recurrent inguinal hernias as opposed to patients with indirect inguinal hernias. The aim of the present study was to assess whether direct or recurrent inguinal hernias are associated with an elevated rate of ventral hernia surgery.

METHODS

In the nationwide Danish Hernia Database, a cohort of 92,457 patients operated on for inguinal hernias was recorded from January 1998 until June 2010. Eight-hundred forty-three (0.91 %) of these patients underwent a ventral hernia operation between January 2007 and June 2010. A multivariate logistic regression analysis was applied to assess an association between inguinal and ventral hernia repair.

RESULTS

Direct (Odds Ratio [OR] = 1.28 [95 % CI, 1.08-1.51]) and recurrent (OR = 1.76, [95 % CI, 1.39-2.23]) inguinal hernias were significantly associated with ventral hernia repair after adjustment for age, gender, and surgical approach (open or laparoscopic).

CONCLUSIONS

Patients with direct and recurrent inguinal herniation are more prone to ventral hernia repair than patients with indirect inguinal herniation. This is the first study to show that herniogenesis is associated with type of inguinal hernia.

Skin as marker for collagen type I/III ratio in abdominal wall fascia

PURPOSE

An altered collagen metabolism could play an important role in hernia development. This study compared collagen type I/III ratio and organisation between hernia and control patients, and analysed the correlation in collagen type I/III ratio between skin and abdominal wall fascia.

METHODS

Collagen organisation was analysed in Haematoxylin-Eosin sections of anterior rectus sheath fascia, and collagen type I/III ratio, by crosspolarisation microscopy, in Sirius-Red sections of skin and anterior rectus sheath fascia, of 19 control, 10 primary inguinal, 10 recurrent inguinal, 13 primary incisional and 8 recurrent incisional hernia patients.

RESULTS

Compared to control patients [7.2 (IQR = 6.8-7.7) and 7.2 (IQR = 5.8-7.9)], collagen type I/III ratio was significantly lower in skin and anterior rectus sheath fascia of primary inguinal [5.2 (IQR = 3.8-6.3) and 4.2 (IQR = 3.8-4.7)], recurrent inguinal [3.2 (IQR = 3.1-3.6) and 3.3 (IQR = 3-3.7)], primary incisional [3.5 (IQR = 3-3.9) and 3.4 (IQR = 3.3-3.6)] and recurrent incisional hernia [3.2 (IQR = 3.1-3.9) and 3.2 (IQR = 2.9-3.2)] patients; also incisional and recurrent inguinal hernia had lower ratio than primary inguinal hernia patients. Furthermore, collagen type I/III ratio was significantly correlated (r = 0.81; P < 0.001) between skin and anterior rectus sheath fascia. Finally, collagen organisation was comparable between hernia and control patients.

CONCLUSIONS

Furthermore, in both skin and abdominal wall fascia of hernia patients, collagen type I/III ratio was lower compared to control patients, with more pronounced abnormalities in incisional and recurrent inguinal hernia patients. Importantly, collagen type I/III ratio in skin was representative for that in abdominal wall fascia.

Importance of recurrence rating, morphology, hernial gap size, and risk factors in ventral and incisional hernia classification

BACKGROUND

There is limited evidence on the natural course of ventral and incisional hernias and the results of hernia repair, what might partially be explained by the lack of an accepted classification system. The aim of the present study is to investigate the association of the criteria included in the Wuerzburg classification system of ventral and incisional hernias with postoperative complications and long-term recurrence.

METHODS

In a retrospective cohort study, the data on 330 consecutive patients who underwent surgery to repair ventral and incisional hernias were analyzed. The following four classification criteria were applied: (a) recurrence rating (ventral, incisional or incisional recurrent); (b) morphology (location); (c) size of the hernial gap; and (d) risk factors. The primary endpoint was the occurrence of a recurrence during follow-up. Secondary endpoints were incidence of postoperative complications. Independent association between classification criteria, type of surgical procedures and postoperative complications was calculated by multivariate logistic regression analysis and between classification criteria, type of surgical procedures and risk of long-term recurrence by Cox regression analysis.

RESULTS

Follow-up lasted a mean 47.7 ± 23.53 months (median 45 months) or 3.9 ± 1.96 years. The criterion "recurrence rating" was found as predictive factor for postoperative complications in the multivariate analysis (OR 2.04; 95 % CI 1.09-3.84; incisional vs. ventral hernia). The criterion "morphology" had influence neither on the incidence of the critical event "recurrence during follow-up" nor on the incidence of postoperative complications. Hernial gap "width" predicted postoperative complications in the multivariate analysis (OR 1.98; 95 % CI 1.19-3.29; ≤5 vs. >5 cm). Length of the hernial gap was found to be an independent prognostic factor for the critical event "recurrence during follow-up" (HR 2.05; 95 % CI 1.25-3.37; ≤5 vs. >5 cm). The presence of 3 or more risk factors was a consistent predictor for "recurrence during follow-up" (HR 2.25; 95 % CI 1.28-9.92). Mesh repair was an independent protective factor for "recurrence during follow-up" compared to suture (HR 0.53; 95 % CI 0.32-0.86).

CONCLUSIONS

The ventral and incisional hernia classification of Dietz et al. employs a clinically proven terminology and has an open classification structure. Hernial gap size and the number of risk factors are independent predictors for "recurrence during follow-up", whereas recurrence rating and hernial gap size correlated significantly with the incidence of postoperative complications. We propose the application of these criteria for future clinical research, as larger patient numbers will be needed to refine the results.

Histologic and immunohistochemical studies of rectus sheath in obese patients

BACKGROUND

Obesity is a well-established risk factor for incisional hernia development. The exact causative factors have not been clearly defined, and development may result from structural disruptions in the connective tissue of the fasciae. The goal of this study was to compare the content of elastin in the rectus muscle sheath of obese patients and nonobese controls.

MATERIALS AND METHODS

The study group consisted of 20 patients with body mass index over 35 kg/m(2) and the control group included 19 patients with normal-range body mass index. The biopsy specimens harvested during surgery were subjected to histologic evaluation, an immunohistochemical reaction with monoclonal anti-elastin antibodies, and the DAB chromatic reaction. The photomicrographs were evaluated using ImageJ software and the percentage of the area affected by the color reaction was assessed. A statistical evaluation was performed.

RESULTS

The specimens harvested from persons in the control group showed in hematoxylin-eosin staining a high density of fibrous elements, arranged in regular bundles. In specimens obtained from the morbidly obese, the density of the fibers was lower and their architecture was disrupted; the bundles were thinner and less regularly arranged. Most photographs show adipose tissue infiltrating the structure of the fascia. Statistical analysis of the percentage of the area occupied by elastin showed a statistically significant difference in favor of the controls.

CONCLUSIONS

The quantitative and qualitative changes in the elastin content of rectus abdominis muscle sheath fascia in the obese population may indicate a possible local mechanism influencing the development of incisional hernias.

Abdominal aortic aneurysm and abdominal wall hernia as manifestations of a connective tissue disorder

BACKGROUND

Abdominal aortic aneurysms (AAAs) and abdominal wall hernias represent chronic degenerative conditions. Both aortic aneurysms and inguinal hernias share common epidemiologic features, and several investigators have found an increased propensity for hernia development in patients treated for aortic aneurysms. Chronic inflammation and dysregulation in connective tissue metabolism constitute underlying biological processes, whereas genetic influences appear to be independently associated with both disease states. A literature review was conducted to identify all published evidence correlating aneurysms and hernias to a common pathology.

METHODS

PubMed/Medline was searched for studies investigating the clinical, biochemical, and genetic associations of AAAs and abdominal wall hernias. The literature was searched using the MeSH terms "aortic aneurysm, abdominal," "hernia, inguinal," "hernia, ventral," "collagen," "connective tissue," "matrix metalloproteinases," and "genetics" in all possible combinations. An evaluation, analysis, and critical overview of current clinical data and pathogenic mechanisms suggesting an association between aneurysms and hernias were undertaken.

RESULTS

Ample evidence lending support to the clinical correlation between AAAs and abdominal wall hernias exists. Pooled analysis demonstrated that patients undergoing aortic aneurysm repair through a midline abdominal incision have a 2.9-fold increased risk of developing a postoperative incisional hernia compared with patients treated for aortoiliac occlusive disease (odds ratio, 2.86; 95% confidence interval, 1.97-4.16; P < .00001), whereas the risk of inguinal hernia was 2.3 (odds ratio, 2.30; 95% confidence interval, 1.52-3.48; P < .0001). Emerging evidence has identified inguinal hernia as an independent risk factor for aneurysm development. Although mechanisms of extracellular matrix remodeling and the imbalance between connective tissue degrading enzymes and their inhibitors instigating inflammatory responses have separately been described for both disease states, comparative studies investigating these biological processes in aneurysm and hernia populations are scarce. A genetic predisposition has been documented in familial and observational segregation studies; however, the pertinent literature lacks sufficient supporting evidence for a common genetic basis for aneurysm and hernia.

CONCLUSIONS

Insufficient data are currently available to support a systemic connective tissue defect affecting the structural integrity of the aortic and abdominal wall. Future investigations may elucidate obscure aspects of aneurysm and hernia pathophysiology and create novel targets for pharmaceutical and gene strategies for disease prevention and treatment.

Impact of pressure and gas type on adhesion formation and biomaterial integration in laparoscopy

BACKGROUND

Laparoscopic mesh repair of inguinal and incisional hernias has been widely adopted. Nevertheless, knowledge about the impact of pneumoperitoneum on mesh integration is rare. The present study investigates pressure and gas-dependent effects of pneumoperitoneum on adhesion formation and biomaterial integration in a standardized animal model.

METHODS

Laparoscopic intraperitoneal onlay mesh implantation (IPOM) was performed in 32 female chinchilla rabbits using CO(2) or helium for pneumoperitoneum. Intra-abdominal pressures were 3 or 6 mmHg. Animals were killed after 21 days, and the abdominal wall was explanted for subsequent histopathological examinations. Adhesions were assessed qualitatively with a scoring system, and the adhesion surface was analyzed semiquantitatively by planimetry. Infiltration of macrophages (CD68), expression of matrix metalloproteinase 13 (MMP-13), and cell proliferation (Ki67) were analyzed at the mesh to host interface by immunohistochemistry. The collagen type I/III ratio was analyzed by cross-polarization microscopy to determine the quality of mesh integration.

RESULTS

After 21 days, perifilamental infiltration with macrophages (CD68) and percentage of proliferating cells (Ki67) were highest after 6 mmHg of CO(2) pneumoperitoneum. The extent of adhesions, as well as the expression of MMP-13 and the collagen type I/III ratio, were similar between groups.

CONCLUSIONS

Our experiments showed no pressure or gas-dependent alterations of adhesion formation and only minor effects on biomaterial integration. Altogether, there is no evidence for a clinically negative effect of CO(2) pneumoperitoneum.

Hiatal hernias: a review of the pathophysiologic theories and implication for research

BACKGROUND

The pathophysiology of hiatal hernias is incompletely understood. This study systematically reviewed the literature of hiatal hernias to provide an evidence-based explanation of the pathogenetic theories and to identify any risk factors at the molecular and cellular levels.

METHODS

A systematic search of the Medline and Pubmed databases on the pathophysiology of hiatal hernias was performed to identify English-language citations from the database inception to December 2010.

RESULTS

Although few studies have examined the relationship of molecular and cellular changes of the diaphragm to the pathogenesis of hiatal hernias, there appear to be three dominant pathogenic theories: (1) increased intraabdominal pressure forces the gastroesophageal junction (GEJ) into the thorax; (2) esophageal shortening due to fibrosis or excessive vagal nerve stimulation displaces the GEJ into the thorax; and (3) GEJ migrates into the chest secondary to a widening of the diaphragmatic hiatus in response to congenital or acquired molecular and cellular changes, such as the abnormalities of collagen type 3 alpha 1.

CONCLUSIONS

The pathogenesis of hiatal hernias at the molecular and cellular levels is poorly described. To date, no single theory has proved to be the definitive explanation for hiatal hernia formation, and its pathogenesis appears to be multifactorial.