Impact of mesh positioning on foreign body reaction and collagenous ingrowth in a rabbit model of open incisional hernia repair

Chitosan thread in the healing of the cecal wall of rabbits (Oryctolagus cuniculus) submitted to cecorrhaphy

The development and evaluation of synthesis materials are crucial to reducing the morbidity and magnitude of post-enterorrhaphy surgical complications. Despite the possibility of production, chitosan thread has not yet been used in enterorrhaphy, and its effects on intestinal healing have not been evaluated. Therefore, this study aimed to evaluate the effects of chitosan thread on the intestinal wall repair of rabbits submitted to cecorrhaphy. For this, 42 rabbits were allocated into two groups with 21 animals. One group was submitted to cecorrhaphy with chitosan suture thread (CG) and the other with poliglecaprone suture thread (PG). The occurrence of postoperative complications, the intensity of edema, cellular response, formation of granulation tissue, as well as the deposition and maturation of collagen fibers, and the intensity of vascular endothelial growth factor (VEGF-α) expression, were evaluated during the intestinal wall repair process. The evaluations occurred on the 5th, 15th, and 25th postoperative (PO) days. The animals did not develop peritonitis, but adherence was observed in six animals from CG and seven from PG, with no difference between groups. The polymorphonuclear infiltrate showed higher intensity and higher amount of type III collagen fibers in CG on the 15th PO day. In contrast, a lower amount of type I collagen fibers was observed in CG samples on the 25th PO day. Therefore, the chitosan thread used for cecorrhaphy in rabbits results in minimal postoperative complications, presents biocompatibility, and bioactively assists the tissue repair process of the cecal wall, inducing minimal tissue reaction, stimulating the deposition of type III collagen fibers in the proliferative phase, with sustained VEGF-α expression, but with reduced deposition of type I fibers, indicating a delay in collagen maturation.

Short-term complications after onlay versus preperitoneal mesh repair of umbilical hernias: a prospective randomized double-blind trial

PURPOSE

To compare the incidence of surgical site occurrences (SSOs) following onlay versus preperitoneal mesh placement in elective open umbilical hernia repairs.

METHODS

This study presents a secondary analysis of a randomized double-blind trial conducted on female patients with primary umbilical hernias admitted to a general hospital, in a residency training program setting. Fifty-six subjects were randomly assigned to either onlay (n=30) or preperitoneal (n=26) mesh repair group. Data on baseline demographics, past medical history, perioperative details, postoperative pain (visual analogue scale (VAS)), wound-related complications, and recurrence were assessed using a standardized protocol.

RESULTS

No statistically significant differences were observed between groups regarding patients' demographics, comorbidities, or defect size. Operative time averaged 67.5 (28-110) min for onlay and 50.5 (31-90) min for preperitoneal repairs, p=.03. The overall rate of SSOs was 21.4% (n=12), mainly in the onlay group (33% vs 7.7%; p=0.02, 95% CI 0.03-0.85) and mostly due to seromas. There were no between-group significant differences in postoperative VAS scores at all timepoints. After a maximum follow-up of 48 months, one recurrence was reported in the onlay group. By logistic regression, the onlay technique was the only independent risk factor for SSOs.

CONCLUSION

The presented data identified a decreased wound morbidity in preperitoneal umbilical hernia repairs, thus contributing to the limited body of evidence regarding mesh place selection in future guidelines. Further cases from this ongoing study and completion of follow-up are expected to also compare both techniques in terms of long-term outcomes.

TRIAL REGISTRATION NUMBER

Brazilian Registry of Clinical Trials (ReBEC) UTN code: U1111-1205-0065 (date of registration: March 27, 2018).

No difference in outcomes between large- and small-pore meshes in a prospective, randomized, multicenter trial investigating open retromuscular meshplasty for incisional hernia repair

STUDY DESIGN

A randomized, controlled, prospective multicenter clinical trial with a parallel group design was initiated in eight surgical centers to compare a large-pore polypropylene mesh (Ultrapro®) to a small-pore polypropylene mesh (Premilene®) within a standardized retromuscular meshplasty for incisional hernia repair.

METHODS

Between 2004 and 2006, patients with a fascial defect with a minimum diameter of 4 cm after vertical midline laparotomy were recruited for the trial. Patients underwent retromuscular meshplasty with either a large-pore or a small-pore mesh to identify the superiority of the large-pore mesh. Follow-up visits were scheduled at 5 and 21 days and 4, 12, and 24 months after surgery. A clinical examination, a modified short form 36 (SF-36®), a daily activity questionnaire, and an ultrasound investigation of the abdominal wall were completed at every follow-up visit. The primary outcome criterion was foreign body sensation at the 12-month visit, and the secondary endpoint criteria were the occurrence of hematoma, seroma, and chronic pain within 24 months postoperatively.

RESULTS

In 8 centers, 181 patients were included in the study. Neither foreign body sensation within the first year after surgery (27.5% Ultrapro®, 32.2% Premilene®) nor the time until the first occurrence of foreign body sensation within the first year was significantly different between the groups. Regarding the secondary endpoints, no significant differences could be observed. At the 2-year follow-up, recurrences occurred in 5 Ultrapro® patients (5.5%) and 4 Premilene® patients (4.4%).

CONCLUSION

Despite considerable differences in theoretical and experimental works, we have not been able to identify differences in surgical or patient-reported outcomes between the use of large- and small-pore meshes for retromuscular incisional hernia repair.

TRIAL REGISTRATION

Clinical Trials NCT04961346 (16.06.2021) retrospectively registered.

A Biomechanical Analysis of Prophylactic Mesh Reinforced Porcine Laparotomy Incisions

INTRODUCTION

Research indicates that prophylactic mesh may help prevent incisional hernia after laparotomy, but best practice patterns in these situations are still evolving. Here, we compare the failure loads (FLs) and biomechanical stiffness (BMS) of 35 porcine abdominal wall laparotomy incisions reinforced with meshes of various widths and fixation distances using biomechanical testing.

METHODS

In each specimen, a 10-cm incision was made and closed using continuous 1-0 Maxon suture. Specimens were randomized to mesh width (none, 2.5 cm, 3 cm, 4 cm, 6 cm, 8 cm) and tack separation (1.5 cm, 2 cm apart) and the meshes secured in an onlay fashion. Cyclic loads oscillating from 15 N to 140 N were applied to simulate abdominal wall stress, and the specimens subsequently loaded to failure. FLs (N) and BMS (N/mm) were comparatively analyzed.

RESULTS

All specimens failed via suture pull-through. FLs and BMS were lowest in specimens with suture-only (421.43 N; 11.69 N/mm). FLs and BMS were significantly higher in 4-cm mesh specimens (567.51 N) than those with suture, 2.5-cm, and 3.0-cm mesh (all P < 0.05). FLs in specimens with a greater number of tacks were consistently higher in meshes of similar sizes, although these did not reach significance.

CONCLUSIONS

A 4-cm mesh reenforcement was superior to suture-only and smaller meshes at preserving strength in laparotomy closure in a porcine model but larger meshes (6 cm, 8 cm) did not provide an additional benefit. Meshes with more fixation points may be advantageous, but additional data are needed to make definitive conclusions.

Determination of thick and thin fibres distribution in Sunda porcupine dorsal skin (Hystrix javanica) using Picrosirius red staining

The complexity of the Sunda porcupine skin has become an important topic due to the unique characteristics of its quill follicles. The structure and chemical composition of the skin has affected many physiological and other conditions. Generally, quills are larger, stronger and stiffer than hair; therefore, the skin structure needs to adapt to support their physiology. The strength of the skin is determined by its collagen composition and arrangement; therefore, this study aims to analyse the composition and distribution of thick and thin fibres based on the specific characteristics of Sunda porcupine skin under polarized light using picrosirius red staining. The skin samples used were from the thoracodorsal and lumbosacral regions of eight Sunda porcupine adults. The histological staining was carried out using the picrosirius red method, while the samples were observed under a polarized light microscope and analysed with software. The results showed that the skin is composed of 36%-65% thick fibres, 20%-35% thin fibres and small amounts of other types with the lumbosacral region having higher compositions of thick and thin fibres than those in the thoracodorsal region. Furthermore, the thoracodorsal and lumbosacral regions have the highest composition of thick fibre in the deeper dermis and quill follicle, respectively. These demonstrated that the complexity of the skin structure of Sunda porcupine due to its quill derivates correlated with its collagen composition and distribution.

Characterization of vaginal immune response to a polypropylene mesh: Diabetic vs. normoglycemic conditions

OBJECTIVE

Urogynecology meshes, typically manufactured from polypropylene, are widely used in the surgical treatment of stress urinary incontinence and pelvic organ prolapse. However, mesh-associated complications such as mesh exposure can develop in women undergoing mesh implantation, for which diabetes is an independent risk factor. We aimed to define the impact of diabetes on the vaginal immune response to mesh by comparing diabetic vs. normoglycemic conditions longitudinally in a rat sacrocolpopexy model.

METHODS

Diabetes (blood glucose ≥ 300 mg/dL) was induced in middle-aged female Wistar rats with streptozotocin (STZ). A polypropylene mesh was implanted on the vagina via modified sacrocolpopexy following bilateral ovariectomy and supracervical hysterectomy for 3-, 7-, and 42-days. Sham-operated controls underwent the same procedures without mesh. Mesh-associated inflammation, immune cell populations and cytokine/chemokine profiles were examined in the excised vaginal tissues.

RESULTS

Diabetes was reliably induced starting on the 3rd day following STZ injection. Under both normoglycemic and diabetic conditions, mesh caused a prolonged inflammatory response in the vagina with increased proinflammatory chemokines MCP-1 and MIP-1α as compared to Sham. Major differences between the two conditions were found at the later stage (42 days post-surgery), including an increased inflammation with larger foreign body granuloma and more giant cells at the mesh-tissue interface, increased fraction of macrophages in the immune cell population, and higher proinflammatory chemokine IP-10 in the diabetic group.

CONCLUSION

Polypropylene mesh implanted on the vagina induces prolonged inflammation at the mesh-tissue interface. Diabetes increases the mesh-associated inflammation in the long term, which is related to a dysregulated macrophage response.

STATEMENT OF SIGNIFICANCE

This study investigated the mechanism underlying the increased risk in women with diabetes for developing mesh complications such as mesh exposure. The significance includes: (1) it is the first study investigating vaginal host response to a prosthesis under the influence of diabetes; (2) the longitudinal study design elucidated the dynamic changes of vaginal immune response to mesh from very early to late stages; (3) our findings may inform future mechanistic studies and studies investigating preventive/therapeutic strategies to improve the outcomes of women with diabetes receiving vaginal implants.

Incisional hernia repair by synthetic mesh prosthesis in patients with inflammatory bowel disease: a comparative analysis

Background

Patients with inflammatory bowel disease (IBD) have a high-life time risk undergoing abdominal surgery and are prone to develop incisional hernias (IH) in the postoperative course. Therefore, we investigated the role of IBD as perioperative risk factor in open ventral hernia repair (OVHR) as well as the impact of IBD on hernia recurrence during postoperative follow-up.

Methods

The postoperative course of 223 patients (Non-IBD (n = 199) and IBD (n = 34)) who underwent OVHR were compared by means of extensive group comparisons and binary logistic regressions. Hernia recurrence was investigated in the IBD group according to the Kaplan–Meier method and risk factors for recurrence determined by Cox regressions.

Results

General complications (≥ Clavien-Dindo I) occurred in 30.9% (72/233) and major complications (≥ Clavien-Dindo IIIb) in 7.7% (18/233) of the overall cohort with IBD being the single independent risk-factor for major complications (OR = 4.2, p = 0.007). Further, IBD patients displayed a recurrence rate of 26.5% (9/34) after a median follow-up of 36 months. Multivariable analysis revealed higher rates of recurrence in patients with ulcerative colitis (UC, 8/15, HR = 11.7) compared to patients with Crohn’s disease (CD, 1/19, HR = 1.0, p = 0.021).

Conclusion

IBD is a significant risk factor for major postoperative morbidity after OVHR. In addition, individuals with IBD show high rates of hernia recurrence over time with UC patients being more prone to recurrence than patients with CD.

Short-term outcomes and healthcare resource utilization following incisional hernia repair with synthetic mesh in patients with Crohn's disease

PURPOSE

While the use of synthetic mesh for incisional hernia repair reduces recurrence rates, little evidence exists regarding the impact of this practice on the disease burden of a Crohn's patient. We aimed to describe the post-operative outcomes and healthcare resource utilization following incisional hernia repair with synthetic mesh in patients with Crohn's disease.

METHODS

A retrospective review of adult patients with Crohn's disease who underwent elective open incisional hernia repair with extra-peritoneal synthetic mesh from 2014 to 2018 at a single large academic hospital with surgeons specializing in hernia repair was conducted. Primary outcomes included 30-day post-operative complications and long-term rates of fistula formation and hernia recurrence. The secondary outcome compared healthcare resource utilization during a standardized fourteen-month period before and after hernia repair.

RESULTS

Among the 40 patients included, six (15%) required readmission, 4 (10%) developed a surgical site occurrence, 3 (7.5%) developed a surgical site infection, and one (2.5%) required reoperation within the first 30 days. The overall median follow-up time was 42 months (IQR = 33-56), during which time one (2.5%) patient developed an enterocutaneous fistula and eight (20%) experienced hernia recurrence. Healthcare resource utilization remained unchanged or decreased across every category following repair.

CONCLUSION

The use of extra-peritoneal synthetic mesh during incisional hernia repair in patients with Crohn's disease was not associated with a prohibitively high rate of post-operative complications or an increase in healthcare resource utilization to suggest worsening disease during the first 4 years after repair. Future studies exploring the long-term outcomes of this technique are needed.

Onlay Poly-4-Hydroxybutyrate (P4HB) Mesh for Complex Hernia: Early Clinical and Patient Reported Outcomes

BACKGROUND

While mesh re-enforcement and advanced surgical techniques are cornerstones of complex ventral hernia repair (CVHR), the risk of complications and recurrence is common. We aim to evaluate the efficacy, safety, and patient reported outcomes (PROs) of patients undergoing CVHR with onlay Poly-4-hydroxybutyrate (P4HB).

METHODS

Adult (>18 y old) patients undergoing VHR with P4HB (Phasix) in the onlay plane by a single surgeon from 01/2015 to 05/2020 were reviewed. VHR was considered complex if patients had significant co-morbidities, large abdominal wall defects, a history of extensive abdominal surgery, and/or concurrent intra-abdominal pathology. A composite of postoperative outcomes including surgical site occurrences (SSO), surgical site infection (SSI), and surgical site occurrences requiring procedural intervention (SSOpi), as well as PROs as defined by the Abdominal Hernia-Q (AHQ), were analyzed.

RESULTS

A total of 51 patients were included with average age and body mass index of 56.4 and 29.9 kg/m². Median follow up was 20 mo with a hernia recurrence rate of 5.9% (n = 3). 21 patients had an SSO (41.2%), 8 had an SSI (15.7%), and 6 had an SSOpi (11.8%). There was an association with Ventral Hernia Working Group ≥ 2 and development of SSO. There was a significant improvement in overall PROs (P < 0.0001) with no difference in those patients with and without complications (P > 0.05).

CONCLUSION

For hernia patients with large defects and complex intra-abdominal pathology, a safe and effective repair is difficult. The use of onlay P4HB was associated with acceptable postoperative outcomes and recurrence rate.

Characterization of innate and adaptive immune cells involved in the foreign body reaction to polypropylene meshes in the human abdomen

Background

Polypropylene (PP) mesh is widely used to reinforce tissues. The foreign body reaction (FBR) to the implant is dominated by innate immune cells, especially macrophages. However, considerable numbers of adaptive immune cells, namely T cells, have also been regularly observed, which appear to play a crucial role in the long-term host response.

Methods

This study investigated the FBR to seven human PP meshes, which were removed from the abdomen for recurrence after a median of one year. Using immunofluorescence microscopy, the FBR was examined for various innate (CD11b⁺ myeloid, CD68⁺ macrophages, CD56⁺ NK) and adaptive immune cells (CD3⁺ T, CD4⁺ T-helper, CD8⁺ cytotoxic, FoxP3⁺ T-regulatory, CD20⁺ B) as well as “conventional” immune cells (defined as cells expressing their specific immune cell marker without co-expressing CD68).

Results

T-helper cells (19%) and regulatory T-cells (25%) were present at comparable rates to macrophages, and clustered significantly toward the mesh fibers. For all cell types the lowest proportions of “conventional” cells (< 60%) were observed at the mesh–tissue interface, but increased considerably at about 50–100 µm, indicating reduced stimulation with rising distance to the mesh fibers.

Conclusion

Both innate and adaptive immune cells participate in the chronic FBR to PP meshes with T cells and macrophages being the predominant cell types, respectively. In concordance with the previous data, many cells presented a “hybrid” pattern near the mesh fibers. The complexity of the immune reaction seen within the foreign body granuloma may explain why approaches focusing on specific cell types have not been very successful in reducing the chronic FBR.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10029-021-02396-7.

A comparative prospective study of short-term outcomes of extended view totally extraperitoneal (e-TEP) repair versus laparoscopic intraperitoneal on lay mesh (IPOM) plus repair for ventral hernia

BACKGROUND

Currently, minimally invasive approach is preferred for the treatment of ventral hernias. After the introduction of extended view totally extraperitoneal (e-TEP) technique, there has been a constant debate over the choice of better approach. In this study, we compare the short-term outcomes of e-TEP and laparoscopic IPOM Plus repair for ventral hernias.

METHODS

This is a comparative, prospective single-center study done at GEM Hospital and research center Coimbatore, India from July 2018 to July 2019. All patients who underwent elective ventral hernia surgery with defect size of 2 to 6 cm were included. Patient demographics, hernia characteristics, operative and perioperative findings, and postoperative complications were systematically recorded and analyzed.

RESULTS

We evaluated 92 cases (n = 92), 46 in each group. Mean age, sex, BMI, location of hernia, primary and incisional hernia, and comorbidity were comparable in both the groups. Mean defect size for IPOM Plus and e-TEP was 4 cm and 3.89 cm, respectively. Operative time was significantly higher for e-TEP, while postoperative pain (VAS), analgesic requirement, and postoperative hospital stay were significantly less as compared to IPOM Plus. However, 2 cases (4.35%) of e-TEP had recurrence but none in IPOM Plus group.

CONCLUSION

e-TEP is an evolving procedure and comparable to IPOM Plus in terms of postoperative pain, analgesic requirement, cost of mesh, and length of hospital stay. More randomized controlled and multicentric studies are required with longer follow-up to validate our findings.

Morphological evaluation of polysaccharide content and collagen composition during cutaneous wound healing in the Sunda porcupine (Hystrix javanica)

Wound healing in the Sunda porcupine is believed to occur quickly, although the wound is large and severe. Wound enclosure involves many processes to restore the lost or damaged skin structure where conjugated polysaccharide-protein and collagen, as the main components deposited in wound tissue to restore it. The aim of this study was to evaluate alteration of polysaccharide contents and collagen in untreated full-thickness wound healing in the thoracodorsal and lumbosacral regions in the Sunda porcupines. Histological analysis was performed by periodic acid Schiff, alcian blue pH 2.5, picrosirius red staining method and Low Vacuum Scanning Electron Microscope (LV-SEM) imaging to obtain the fundamental data of healing process. Wound healing began with re-epithelization followed by progressive wound contraction with 4 overlapping stages in about 30–50 days until the wound closed (21–30 days in thoracodorsal and 30–50 days in lumbosacral). Neutral polysaccharide was more widely distributed compared to the acid polysaccharide in almost all stages of wound healing. The ratio of collagen I to III appeared to be higher in the thoracodorsal region than the lumbosacral region during healing process. LV-SEM imaging showed changes in connective tissue structure in the wound border and granulation tissue which appeared abundant and mixed of thin and thick fiber. In conclusion, cutaneous full thickness wound healing in the Sunda porcupine occurred faster in the thoracodorsal region, which might be correlated to the role of neutral polysaccharide and a high ratio of collagen I to III.

Extended Totally Extraperitoneal (eTEP) Approach for Ventral Hernia Repair: Initial Results

INTRODUCTION

Since the first laparoscopic incisional hernia repair, several minimally invasive procedures have been developed in abdominal wall repair. In 2017, the extended totally extraperitoneal (eTEP) approach for abdominal wall repair was published. We present the results from eTEP implementation at two medical centers by one surgeon.

METHODS

Prospective descriptive study of the implementation of the eTEP approach, with transversus abdominis release (TAR) when needed. The surgical technique was initiated by accessing the space between the rectus abdominis muscle and posterior rectus sheath, connecting this space with the fatty preperitoneal space at the midline and the contralateral retrorectal space. Identification and dissection of the hernia sac is performed in the created cavity. Additionally, posterior component release in a TAR fashion could be done. Finally, closure of posterior plane and linea alba is completed and mesh prosthesis is deployed along the whole dissected space.

RESULTS

Forty patients underwent an eTEP procedure with 20 supraumbilical defects, 10 infraumbilical and 10 lateral hernias. Sixteen cases required a TAR technique. Mean operative time was 126minutes. Median pain reported the first postoperative day was 3 on the visual analogue scale. Median length of stay was 1 day and mean follow-up was 10 months. Only one patient developed recurrence, and two patients underwent reoperation.

CONCLUSIONS

Implementation of eTEP in abdominal wall repair is safe. Preliminary outcomes of the eTEP approach in ventral hernia repair show good pain control with less hospital stay.

Robotic intraperitoneal onlay versus totally extraperitoneal (TEP) retromuscular mesh ventral hernia repair: A propensity score matching analysis of short-term outcomes

BACKGROUND

Short-term outcomes of robotic intraperitoneal onlay mesh(rIPOM) versus robotic totally extraperitoneal retromuscular mesh(rTEP-RM) ventral hernia repair were compared.

METHODS

A retrospective review of prospectively collected data of patients was conducted. A one-to-one propensity score matching(PSM) analysis was performed to achieve two well-balanced groups in terms of preoperative variables. A univariate and multivariate analysis were conducted to determine factors influencing post-operative outcomes.

RESULTS

Of 291 rIPOM and rTEP-RM procedures, 68 patients were assigned to each group after PSM. Operative times were longer for the rTEP-RM group. Adhesiolysis was more frequently required in rIPOM. The rTEP-RM allowed for a greater mesh-to-defect ratio. The rate of overall perioperative complications, Clavien-Dindo grades, and surgical site events were higher for the rIPOM group than the rTEP-RM group. The Comprehensive Complication Index® morbidity scores were lower in favor of rTEP-RM group. Adhesiolysis, rIPOM, and craniocaudal defect size were predictors for post-operative complications.

CONCLUSION

Robotic TEP-RM repair has better early postoperative outcomes for ventral hernias, suggesting that it may be preferable over robotic IPOM repair. Further studies with longer follow-up are needed.

Retromuscular Mesh Repair Using Extended Totally Extraperitoneal Repair Minimal Access: Early Outcomes of an Evolving Technique-A Single Institution Experience

Background: Enhanced-view extended totally extraperitoneal repair (eTEP) technique for laparoscopic retromuscular ventral hernia (VHR) repair is a novel application recently described by some authors. We present our early single institution experience on this technique. Methods: Retrospective review of the eTEP technique for laparoscopic retromuscular VHR repair cases at our institution from October 2018 to June 2019 with 1 month follow-up was evaluated. Data analyses include patients characteristics, operative details, and complications. Results: A total of 18 patients were treated with eTEP. One patient was reoperated using the same procedure and hospital stay was 6 days. The same patient who had undergone transversus abdominis release developed a seroma that could be observed 20 days after surgery. Conclusion: Our short-term experience with eTEP access suggests feasibility of this approach in accordance with results from other authors. We do not think the technique is challenging, but it is necessary for it to be performed by surgeons with skills in laparoscopic abdominal wall reconstruction.

Landmarks in vaginal mesh development: polypropylene mesh for treatment of SUI and POP

Vaginal meshes used in the treatment of stress urinary incontinence (SUI) and pelvic organ prolapse (POP) have produced highly variable outcomes, causing life-changing complications in some patients while providing others with effective, minimally invasive treatments. The risk:benefit ratio when using vaginal meshes is a complex issue in which a combination of several factors, including the inherent incompatibility of the mesh material with some applications in pelvic reconstructive surgeries and the lack of appropriate regulatory approval processes at the time of the premarket clearance of these products, have contributed to the occurrence of complications caused by vaginal mesh. Surgical mesh used in hernia repair has evolved over many years, from metal implants to knitted polymer meshes that were adopted for use in the pelvic floor for treatment of POP and SUI. The evolution of the material and textile properties of the surgical mesh was guided by clinical feedback from hernia repair procedures, which were also being modified to obtain the best outcomes with use of the mesh. Current evidence shows how surgical mesh fails biomechanically when used in the pelvic floor and materials with improved performance can be developed using modern material processing and tissue engineering techniques.

Dynamic changes of the extracellular matrix during corneal wound healing

The extracellular matrix (ECM) confers transparency to the cornea because of the precise organization of collagen fibrils and a wide variety of proteoglycans. We monitored the corneal wound healing process after alkali burns in rabbits. We analyzed the location and expression of collagens and proteoglycans, the clinical impact, and the recovery of optical transparency. After the animals received both general and ocular topical anesthesia, the central cornea of the left eye was burned by placing an 8-mm diameter filter paper soaked in 0.5 N NaOH for 60 s. The eyes were evaluated under a surgical microscope at 1, 3, and 6 months after burning. At each time point, the clinical conditions of the burned and control corneas were observed. The arrangement of collagen fibers in the corneal stroma was visualized by Picrosirius-red staining, Gomori's silver impregnation and transmission electronic microscopy. Corneal light transmittance was also measured. Myofibroblasts presence was analyzed by immunohistochemistry. mRNA expression levels of collagen types I and III, lumican, decorin, keratocan and alpha-smooth muscle actin were determined by quantitative real-time polymerase chain reaction. One month after alkali burn, the ECM was disorganized and filled with lacunae containing different types of cells and collagen type III fibers in the wound area. Corneal opacities were present with attendant loss of light transmittance. Collagen and proteoglycan mRNA expression levels were up-regulated. After three months, wound healing progress was indicated by reduced corneal opacity, increased light transmittance, reorganization of collagen fibers and only collagen type I expression levels were at control levels. After six months, the wound area ECM morphology was similar to controls, but transmittance values remained low, denoting incomplete restoration of the stromal architecture. This multidisciplinary study of the stromal wound healing process revealed changes in corneal transmittance, collagen organization, myofibroblasts presence and ECM composition at 1, 3, and 6 months after alkali burning. Documenting wound resolution during the six-month period provided reliable information that can be used to test new therapies.

Comparison of Surgisis, Vypro II and TiMesh in contaminated and clean field

PURPOSE

The study aimed to evaluate the histologic properties and infection resistance of three different mesh materials in a rat model.

METHODS

Each mesh, in both infectious (n = 96) and non-infectious groups (n = 270), was positioned both in sublay (preperitoneally) and onlay (subcutaneously) locations. Properties of the biological (Surgisis; Cook Surgical), composite, partially resorbing (Vypro II mesh; Ethicon) and non-resorbing (TiMesh; GFE Medizintechnik GmbH) mesh were evaluated and compared. Animals were killed at 7, 21 and 90 days after implantation. The following parameters were evaluated to assess the host response to the mesh material: inflammation, vascularization, fibrosis, collagen formation, Ki67, and a foreign body reaction by granuloma formation (FBG).

RESULTS

Surgisis mesh produced more pronounced inflammation and cell proliferation, and less intense granuloma formation, as well as fibrosis, compared to the other two groups. When the infected materials were examined, we found signs of local infection to be more often present in Surgisis group of animals.

CONCLUSIONS

In the presence of bacterial contamination, no benefits were observed in the use of the Surgisis prosthesis over the use of TiMesh and Vypro II.

Complications related to use of mesh implants in surgical treatment of stress urinary incontinence and pelvic organ prolapse: infection or inflammation?

The surgical mesh material used in the surgical treatment of stress urinary incontinence (SUI) and pelvic organ prolapse (POP) in women is associated with significant complications in some women. This has recently become a public health issue with involvement of national parliaments and regulatory bodies. The occurrence of mesh complications is thought to be a result of multifactorial processes involving problems related to the material design, the surgical techniques used and disease, and patient-related factors. However, the infectious complications and mesh–tissue interactions are least studied. The aim of this article is to review any previous clinical and basic scientific evidence about the contribution of infectious and inflammatory processes to the occurrence of mesh-related complications in SUI and POP. A literature search for the relevant publications without any time limits was performed on the Medline database. There is evidence to show that vaginal meshes are associated with an unfavourable host response at the site of implantation. The underlying mechanisms leading to this type of host response is not completely clear. Mesh contamination with vaginal flora during surgical implantation can be a factor modifying the host response if there is a subclinical infection that can trigger a sustained inflammation. More basic science research is required to identify the biological mechanisms causing a sustained inflammation at the mesh–tissue interface that can then lead to contraction, mesh erosion, and pain.

Is Onlay Polypropylene Mesh Repair an Available Option for Incisional Hernia Repair? A Retrospective Cohort Study

Lately, incisional hernia repair (IHR) with onlay polypropylene mesh has been replaced by other surgical procedures. The aim of this study was to compare the complication and recurrence rate after onlay mesh repair and other surgical procedures for IHR. A retrospective cohort study of patients who underwent IHR in a single center was conducted. The data were obtained from electronic medical records. Patients who had been lost during follow-up were contacted for a visit in the clinic. Univariate and multivariate analysis was performed with Stata 13.0 to analyze the factors associated with postoperative complications and hernia recurrence. Between June 2004 and December 2015, 1078 patients underwent IHR in a single center. Onlay mesh repair was performed in 125 patients (11.6%). Other surgical procedures included Rives procedure (29.3%), sublay mesh repair (38.6%), intrabdominal mesh repair (17.1%), and primary closure (3.4%). After a mean follow-up of 2.8 years, 73 (7%) patients developed a recurrence. A higher percentage of complications were seen after onlay mesh repair than after other surgical procedures (22.4% vs 13.1%, P = 0.005). Nevertheless, recurrence was less frequent after onlay mesh repair (4.2% vs 7.1%, P = 0.241). Logistic regression discarded an association between onlay mesh repair and hernia recurrence or postoperative complications. Incisional hernia repair with onlay polypropylene mesh repair was not associated with a higher incidence of postoperative complications or recurrence rate. So, this procedure should not be discarded in selected patients presenting with incisional hernia.

Extended totally extraperitoneal repair (eTEP) for ventral hernias: Short-term results from a single centre

Introduction:

There has been a surge of innovative procedures in the field of abdominal wall hernias. Works of pioneers such as Dr. Yuri Novitsky, Dr. Jorge Daes and Dr. Igor Belyansky have started a new era in the field of hernia surgery. Conventional and popular surgeries for ventral hernias are open onlay mesh hernioplasty, open retromuscular mesh hernioplasty (Rives-Stoppa procedure) and laparoscopic intraperitoneal mesh hernioplasty. Evidence seems to suggest that retromuscular mesh hernioplasty has advantages over other procedures regarding recurrence and surgical site occurrences. An alternative strategy has been developed for this setting where a mesh is placed in retromuscular space by minimal access technique of the extended Totally Extraperitoneal approach (eTEP).

Methods:

We have retrospectively analysed the data of 21 patients who underwent an eTEP procedure with a minimum follow-up of 2 months. Their data were analysed for operative details, intra-operative and post-operative complications.

Results:

For a total of 21 patients, we have recorded a total of two surgical site occurrences (1 seroma and 1 linea alba dehiscence) and one recurrence. One patient had chronic pain. There was no surgical site infection.

Conclusion:

Judging from our short-term results, we suggest that the eTEP technique can be adapted in centres with advanced laparoscopic skills with the careful patient selection.

Retro-rectus placement of bio-absorbable mesh improves patient outcomes

BACKGROUND

There is little consensus on the ideal anatomical placement of bio-absorbable mesh. We hypothesized that retro-rectus placement of bio-absorbable mesh would significantly reduce recurrence rates when compared to intraperitoneal mesh placement.

METHODS

A retrospective review was conducted of patients who underwent open complex ventral hernia repair using bio-absorbable mesh (Bio-A, Gore, Flagstaff, AZ). Patient demographics and Centers for Disease Control wound type were collected.

RESULTS

A total of 81 patients were included. Seventy-four (91.4%) of these hernia repairs had mesh in the retro-rectus position, while 7 (8.6%) had intraperitoneal mesh placement. Patient demographics, including preoperative comorbidities, did not differ between groups. The retro-rectus group trended to have larger hernia defects (156.2 cm²) compared to the intraperitoneal group (63.9 cm²) (p = 0.058). Overall complications (e.g., dehiscence, wound drainage, cellulitis, sepsis) were also similar in both groups of patients. Recurrence rates in the retro-rectus and intraperitoneal group were 8.1% and 42.9%, respectively (p = 0.005). When evaluating only patients with CDC class 1 wounds, the recurrence rate in the retro-rectus group was 8.2% and the intraperitoneal group was 50% (p = 0.02). Overall, the average patient follow-up was 22 months and did not differ between groups. Both the retro-rectus and intraperitoneal groups indicated a significant (p < 0.05) improvement in quality of life from baseline. No long-term (> 7 days) antibiotics were used and no mesh implants were removed during the study.

CONCLUSION

Patients who underwent open complex ventral hernia repairs with bio-absorbable mesh in the retro-rectus position experienced lower overall complication rates than those with intraperitoneal mesh placement. Despite a larger hernia defect in the retro-rectus group, recurrence rates were significantly reduced with retro-rectus placement of mesh compared to intraperitoneal placement. In addition, recurrence rates using bio-absorbable mesh in clean wounds are comparable to previously published recurrence rates with permanent mesh.

Sublay repair results in superior mesh incorporation and histological fibrogenesis in comparison to onlay and primary suture in an experimental rat model

PURPOSE

To compare adhesion scores, repair strength and histological findings among sublay, onlay and primary repair incisional hernioplasty techniques. Surgical repairs were employed directly on healthy animals, without previous hernia induction, to avoid confounding factors related to hernia development.

METHODS

Forty Wistar rats were divided into four groups, control, simulation, onlay and sublay. After 42 days, adhesion intensity, tensile strength of the abdominal wall and anatomopathological histological substrate were compared.

RESULTS

SL group presented greater adhesion scores (p < 0.0001), higher tensiometric (p < 0.0001), and was characterized by more histiocytes, mononuclear cells, macrovacuolar granulomas and type I collagen on histological analysis. Pearson correlation between adhesions and tensiometry, and between tensiometry and neocollagenization showed a strong positive association (r = 0.8905 and 0.6757, respectively in SL group, p < 0.05).

CONCLUSION

Mesh positioning in sublay compartment was followed by increased adhesion development and provides a stronger mesh-tissue attachment, in addition, resulted in a different histological profile of the inflammation/repair substrate. The intensity of these findings was directly correlated, suggesting they could be the result of a common biological phenomenon. Our findings indicate that mesh placement following the retromuscular technique generates a superior repair response, and give clues to a better understanding of the superiority of sublay repair in achieving lower recurrence rates. Characterization of the cellular and molecular elements responsible for the superiority of this technique is in our view an essential prerequisite aiming for improvements in the therapeutic options for the treatment of this disease.

Surgical perspectives regarding application of biomaterials for the management of large congenital diaphragmatic hernia defects

This review focuses on the surgical viewpoints on patch repairs in neonates with large congenital diaphragmatic hernia defects. The main focus  is on the various biomaterials that have been employed to date with regard to their source of origins, degradation properties as well as tissue integration characteristics. Further focus  is on the present knowledge on patch integration when biomaterials are placed in the diaphragmatic defect. The review will also look at the present evidence on the biomechanical characteristics of the most commonly used biomaterials and compares these materials to diaphragmatic tissue to offer more  insight on the present practice of patch repairs in large defects. Since tissue engineering and regenerative medicine has offered another dimension to diaphragmatic replacement, a detailed overview of this technology will be undertaken with regard to cell sourcing, scaffolds, in vitro versus in vivo implants as well as quality of tissue produced, to explore the limitations and the feasibility facing the scientific community in its clinical implementation of skeletal muscle-engineered tissue beyond laboratory research for diaphragmatic replacement.

Intraluminal mesh migration causing enteroenteric and enterocutaneous fistula: a case and discussion of the 'mesh problem'

The use of synthetic mesh in the abdominal compartment has recently become a topic of debate as high profile public cases have called into question their safety. Several case reports have demonstrated significant complications due to intra-abdominal mesh. Furthermore, some studies have suggested that the rates of these severe complications are underestimated. We present the case of a patient who developed an enteroenteric and enterocutaenous fistulae, an abdominal wall collection and an intraperitoneal inflammatory mass from intraluminal migration of a synthetic mesh inserted during laparoscopic incisional hernia repair. We discuss the considerations and complications of using synthetic mesh for ventral hernia repair and discuss the scientific evidence behind the increasingly apparent 'mesh problem'.

Structure and collagen crimp patterns of functionally distinct equine tendons, revealed by quantitative polarised light microscopy (qPLM)

Structure-function relationships in tendons are directly influenced by the arrangement of collagen fibres. However, the details of such arrangements in functionally distinct tendons remain obscure. This study demonstrates the use of quantitative polarised light microscopy (qPLM) to identify structural differences in two major tendon compartments at the mesoscale: fascicles and interfascicular matrix (IFM). It contrasts functionally distinct positional and energy storing tendons, and considers changes with age. Of particular note, the technique facilitates the analysis of crimp parameters, in which cutting direction artefact can be accounted for and eliminated, enabling the first detailed analysis of crimp parameters across functionally distinct tendons.

IFM shows lower birefringence (0.0013 ± 0.0001 [−]), as compared to fascicles (0.0044 ± 0.0005 [−]), indicating that the volume fraction of fibres must be substantially lower in the IFM. Interestingly, no evidence of distinct fibre directional dispersions between equine energy storing superficial digital flexor tendons (SDFTs) and positional common digital extensor tendons (CDETs) were noted, suggesting either more subtle structural differences between tendon types or changes focused in the non-collagenous components.

By contrast, collagen crimp characteristics are strongly tendon type specific, indicating crimp specialisation is crucial in the respective mechanical function. SDFTs showed much finer crimp (21.1 ± 5.5 µm) than positional CDETs (135.4 ± 20.1 µm). Further, tendon crimp was finer in injured tendon, as compared to its healthy equivalents. Crimp angle differed strongly between tendon types as well, with average of 6.5 ± 1.4° in SDFTs and 13.1 ± 2.0° in CDETs, highlighting a substantially tighter crimp in the SDFT, likely contributing to its effective recoil capacity.

Statement of Significance

This is the first study to quantify birefringence in fascicles and interfascicular matrix of functionally distinct energy storing and positional tendons. It adopts a novel method – quantitative polarised light microscopy (qPLM) to measure collagen crimp angle, avoiding artefacts related to the direction of histological sectioning, and provides the first direct comparison of crimp characteristics of functionally distinct tendons of various ages.

A comparison of matched picrosirius red stained and unstained tendons sections identified non-homogenous staining effects, and leads us to recommend that only unstained sections are analysed in the quantitative manner.

qPLM is successfully used to assess birefringence in soft tissue sections, offering a promising tool for investigating the structural arrangements of fibres in (soft) tissues and other composite materials.

Influence of MMP inhibitor GM6001 loading of fibre coated polypropylene meshes on wound healing: Implications for hernia repair

Polypropylene meshes are standard for hernia repair. Matrix metalloproteinases play a central role in inflammation. To reduce the inflammatory response and improve remodelling with an associated reduction of hernia recurrence, we modified polypropylene meshes by nanofibre coating and saturation with the broad-spectrum matrix metalloproteinase inhibitor GM6001. The aim was to modulate the inflammatory reaction, increase collagen deposition and improve mesh biointegration. Polypropylene meshes were surface-modified with star-configured NCO-sP(EO -stat-PO) and covered with electrospun nanofibres (polypropylene-nano) and GM6001 (polypropylene-nano-GM). In a hernia model, defects were reconstructed with one of the meshes. Inflammation, neovascularization, bio-integration, proliferation and apoptosis were assessed histologically, collagen content and gelatinases biochemically. Mesh surface modification resulted in higher inflammatory response compared to polypropylene. Pro-inflammatory matrix metalloproteinase-9 paralleled findings while GM6001 reduced matrix metalloproteinase-9 significantly. Significantly increased matrix metalloproteinase-2 beneficial for remodelling was noted with polypropylene-nano-meshes. Increased vascular endothelial growth factor, neo-vascularization and collagen content were measured in polypropylene-nano-meshes compared to polypropylene. GM6001 significantly reduced myofibroblasts. This effect ended after d14 due to engineering limitations with release of maximal GM6001 loading. Nanofibre-coating of polypropylene-meshes confers better tissue vascularization to the cost of increased inflammation. This phenomenon can be only partially compensated by GM6001. Future research will enable higher GM6001 uptake in nano-coated meshes and may alter mesh biointegration in a more pronounced way.

Comparative study of Polypropylene versus Parietex composite®, Vicryl® and Ultrapro® meshes, regarding the formation of intraperitoneal adhesions

PURPOSE

To compare the polypropylene mesh (Marlex®) to Vicryl®, Parietex composite® and Ultrapro® meshes to assess the occurrence of adhesions in the intraperitoneal implantation.

METHODS

Sixty Wistar rats were allocated into three groups: PP+V, in which all the animals received a polypropylene and a Vicryl® mesh; PP+PC, with the implantation of polypropylene and Parietex composite® meshes and PP+UP, in which there was implantation of polypropylene and Ultrapro®. Macroscopic analysis was performed 28 days later to assess the percentage of mesh area affected by adhesion.

RESULTS

in the PP+ V group, the Vicryl® mesh showed lower adhesion formation (p=0.013). In the PP+PC, there were no differences between polypropylene and Parietex composite® (p=0.765). In the PP+UP group, Ultrapro® and polypropylene meshes were equivalent (p=0.198) .

CONCLUSION

All the four meshes led to adhesions, with the Vicryl® mesh showing the least potential for its formation.

Outcomes of Posterior Component Separation With Transversus Abdominis Muscle Release and Synthetic Mesh Sublay Reinforcement

OBJECTIVE

To evaluate the safety and efficacy of transversus abdominis muscle release (TAR) with retrorectus synthetic mesh reinforcement in a large series of complex hernia patients.

BACKGROUND

Posterior component separation via TAR during abdominal wall reconstruction (AWR) continues to gain popularity. Although our early experience with TAR has been promising, long-term outcomes have not been reported.

METHODS

From December 2006 to December 2014, consecutive patients undergoing open AWR utilizing TAR were identified in our prospectively maintained database and reviewed retrospectively. Main outcome measures included demographics, perioperative details, wound complications, and recurrences.

RESULTS

During the study period, 428 consecutive TAR procedures were analyzed. Mean age was 58, with mean body mass index 34.4 kg/m (range 20-65). Major comorbidities included diabetes (21%), chronic obstructive pulmonary disease (12%), and immunosuppression (3%). Mean hernia defect area was 606 cm (range 180-1280) and average mesh size was 1220 cm (range 600-4500). The majority of cases (66%) were clean, 26% were clean-contaminated, and 8% were contaminated. Eighty (18.7%) surgical-site events occurred, of which 39 (9.1%) were surgical-site infections. Three patients required mesh debridement; however, no instances of mesh explantation occurred. Of the 347 (81%) patients with at least 1-year follow-up (mean 31.5 mo), there were 13 (3.7%) recurrences.

CONCLUSIONS

Complex AWR represents a formidable surgical challenge. In this large series, we demonstrated that posterior component separation via TAR with wide synthetic mesh sublay provides a very durable repair with low morbidity, even in comorbid patients with large defects. We strongly advocate TAR as a robust addition to the armamentarium of reconstructive surgeons.

Open retromuscular mesh repair versus onlay technique of incisional hernia: A randomized controlled trial

INTRODUCTION

The aim of this prospective randomized clinical study was to compare and analyze the results of two methods of treatment of incisional hernia: open retromuscular mesh repair and onlay technique.

METHODS

180 patients who underwent open elective surgery for middle primary incisional hernia were randomized into two groups. The retomuscular mesh repair was used in the first group and the onlay technique - in the second group. Several preoperative and intraoperative factors, also wound complications (wound infection, hematoma, seroma) and hernia recurrence rate were determined and compared between the groups.

RESULTS

The operative time was significantly longer in the retromuscular group compared with the onlay group (P < 0.001). In the retromuscular group 17 (22.1%) wound complications were observed, in the onlay group-39 (50.0%) wound complications. The difference was statistically significance (P < 0.001). Seroma was the most frequent postoperative wound complication, ranging from 16.9% to 41.0% among the groups, respectively (P = 0.0013). No significantly difference has been found between groups by wound infection and hematoma. 2 (2.6%) case of hernia recurrence was marked in retromuscular group and 4 (5.1%) case of hernia recurrence - in onlay group. But there was no statistically significantly difference between the two groups.

CONCLUSION

Our research shows no significant difference in frequency of hernia recurrence between retromuscular mesh repair and onlay technique for treatment of incisional hernia. The usage of the retromuscular mesh repair is associated with significantly less wound complications than onlay technique. That can be considered as an advantage of retromuscular method, which makes it more preferential than onlay method.

Outcomes of Retromuscular Approach for Abdominal Wall Reconstruction in Patients with Inflammatory Bowel Disease

Ventral hernia repair (VHR) in patients with inflammatory bowel disease (IBD) presents unique surgical challenges including impaired wound healing, concomitant intestinal operations, along with likely future abdominal surgeries. Appropriate techniques and mesh choices in these patients remain under active debate. Herein we report our experience with using a retromuscular approach for major VHR in a consecutive cohort of IBD patients. We identified all patients with IBD undergoing open VHR with retrorectus mesh placement between 2007 and 2013 in our prospectively maintained database. Main outcomes included patient and hernia characteristics, perioperative details, wound complications, and hernia recurrence. A total of 38 patients with IBD met inclusion criteria. Mean hernia defect size was 338 cm2. Synthetic mesh was used in 16 patients and biologic mesh was used in 22 of patients. A surgical site occurrence (SSO) occurred in 13 (34.2%) patients, 7 (18.4%) of which were surgical site infections (SSIs). There were no instances of postoperative intestinal complications or enterocutaneous fistulae. At the mean follow-up 37 months, there were 3 (9.4%) recurrences. Our retromuscular repairs were associated with a low rate of wound morbidity and no intestinal complications. Furthermore, we report a relatively low rate of recurrences, especially in this series of complex multiply recurrent hernias. Overall, our retromuscular approach seems to be safe and effective in hernia patients with IBD.

Sublay versus underlay in open ventral hernia repair

BACKGROUND

The ideal location for mesh placement in open ventral hernia repair (OVHR) remains under debate. Current trends lean toward underlay or sublay repair. We hypothesize that in patients undergoing OVHR, sublay versus underlay placement of mesh results in fewer surgical site infections (SSIs) and recurrences.

MATERIALS AND METHODS

A multi-institution database of all OVHRs performed from 2010 to 2011 was accessed. Patients with mesh placed in the sublay or underlay position and at least 1 mo of follow-up were included. Primary outcome was SSI. Secondary outcome was hernia recurrence. Multivariate analysis was performed using logistic regression for SSI and Cox regression for recurrence. Subgroup analysis of elective, midline ventral incisional hernias was also performed.

RESULTS

Of 447 patients, 139 (31.1%) had a sublay repair. The unadjusted analysis showed no difference in SSI and lower recurrence using sublay compared with underlay. On multivariate analysis, there was no difference in SSI using sublay compared with underlay (odds ratio 1.5, 95% confidence interval [CI] 0.8-2.8). Recurrence was less common with sublay (hazard ratio 0.4, 95% CI 0.2-0.8). On subgroup analysis of elective, midline incisional hernias only (n = 247), there were more SSIs with sublay compared with underlay repair (28.0% versus 15.1%, P = 0.018); however, there was no difference in major SSI (sublay 9.3% versus underlay 5.8%, P = 0.315). There were fewer recurrences using sublay repair compared with underlay repair (10.7% versus 25.0%, P = 0.010).

CONCLUSIONS

In this multi-center, risk-adjusted study, sublay repair was associated with fewer recurrences than underlay repair and no difference in SSI. Randomized controlled trials are warranted to validate these findings.

Use of surgical mesh of different compositions in the correction of the abdominal wall defect in rats

OBJECTIVE

To analyze the performance of two surgical meshes of different compositions during the defect healing process of the abdominal wall of rats.

METHODS

thirty-three adult Wistar rats were anesthetized and subjected to removal of an area of 1.5 cm x 2 cm of the anterior abdominal wall, except for the skin; 17 animals had the defect corrected by edge-to-edge surgical suture of a mesh made of polypropylene + poliglecaprone (Group U--UltraproTM); 16 animals had the defect corrected with a surgical mesh made of polypropylene + polidioxanone + cellulose (Group P--ProceedTM). Each group was divided into two subgroups, according to the euthanasia moment (seven days or 28 days after the operation). Parameters analyzed were macroscopic (adherence), microscopic (quantification of mature and immature collagen) and tensiometric (maximum tension and maximum rupture strength).

RESULTS

there was an increase in collagen type I in the ProceedTM group from seven to 28 days, p = 0.047. Also, there was an increase in the rupture tension on both groups when comparing the two periods. There was a lower rupture tension and tissue deformity with ProceedTM mesh in seven days, becoming equal at day 28.

CONCLUSION

the meshes retain similarities in the final result and more studies with larger numbers of animals must be carried for better assessment.

Influence of gentamicin-coded PVDF suture material on the healing of intestinal anastomosis in a rat model

PURPOSE

Intestinal anastomosis is a fundamental procedure in general surgery and required to restore intestinal continuity following resection. The aim of this study was to evaluate whether a gentamicin-coated polyvinylidene fluoride (PVDF) suture material has beneficial effect on anastomotic healing.

METHODS

Ninety Sprague-Dawley rats were divided into three groups: a PVDF-suture group, a gentamicin-coated PVDF (GPVDF)-suture group and a control group using Maxon® (polyglycolid-co-trimethylene carbonate). For each animal, a colonic anastomosis was performed. Ten animals from each group were sacrificed on postoperative days 3, 5, and 14. Measurements of anastomotic bursting pressure were performed on days 3 and 5. At each time, collagen type I/III ratio, MMP 2 and MMP-9 expression and the proliferation index (Ki67) were analyzed.

RESULTS

In total, 90 animals underwent surgery without postoperative complications. Bursting strength in the GPVDF group was significantly elevated on day 5. Immunohistochemistry showed significant increase of the collagen type I/III ratio for PVDF and GPVDF on days 3 and 5. MMP2 was significantly increased for PVDF on days 3 and 5 and for GPVDF on day 5. The analysis of MMP9 revealed significant increase compared to control on day 3 and 5 (GPVDF) as well as on day 5 (PVDF). Staining for Ki67 revealed a significant elevation on postoperative day 3 for the PVDF and the GPVDF group.

CONCLUSIONS

The present data shows the feasibility of PVDF as suture material for colonic anastomosis and confirms the ability of gentamicin to increase the stability of colonic anastomosis when used as coating material.

Open retromuscular mesh repair of complex incisional hernia: predictors of wound events and recurrence

BACKGROUND

Mesh repair of incisional hernias has been consistently shown to diminish recurrence rates after repair, with an increased risk of infectious complications. We present a consecutive series of elective, retrorectus mesh repairs of the abdominal wall and attempt to determine predictors of wound events and recurrence.

STUDY DESIGN

A retrospective review was performed to include elective, retromuscular mesh repairs of complex incisional hernias from August 2006 to August 2013. Demographics, operative details, and postoperative events including wound events, surgical site infections (SSI), and recurrences were recorded.

RESULTS

Over the 7-year period, 255 retromuscular mesh repairs of midline incisional defects were performed. Median age of the patients was 58 years, with an average BMI of 32.2 kg/m(2). Average size of the fascial defect was 181.4 cm(2), with recurrent defects making up 48% of repairs. Wound events occurred in 37.7% of cases; SSIs occurred in 19.6% of cases. Recurrence rate was 16.9%, with mean time to recurrence of 19.2 months. With respect to mesh type, recurrences were 16.2% with synthetic, 17.1% for bioabsorbable, and 25% for biologic mesh. When evaluating polypropylene meshes, recurrence was more likely with lightweight mesh (22.9%) vs midweight mesh (10.6%) (p = 0.045). Predictors of SSI included history of mesh infection (odds ratio [OR] 4.8, 95% CI 1.9 to 12.1; p < 0.001) and recurrent repairs (OR 2.5, 95% CI 1.1 to 5.8; p < 0.05). The only predictor of recurrence was the presence of an SSI (OR 3.1, 95% CI 1.5 to 6.3; p < 0.01).

CONCLUSIONS

Wound events are common after open mesh repairs of complex incisional hernias. Previous mesh infections and recurrent repairs increase the likelihood of an SSI, which significantly increases the risk of recurrence. Recurrences after retrorectus mesh repairs are significantly higher with lightweight compared with mid-weight meshes.

Evaluation of three purely polypropylene meshes of different pore sizes in an onlay position in a New Zealand white rabbit model

BACKGROUND

The aim of the study was to evaluate the influence of the pore size of a polypropylene mesh on the shrinkage and elasticity of the mesh-tissue complex and the inflammatory reaction to the implant in an open onlay hernia repair.

MATERIALS AND METHODS

Twenty-one 10 × 10 cm samples of polypropylene meshes of a different pore size (3.0 × 2.8 mm-PP3, 1.0 × 0.8 mm-PP1 and 0.6 × 0.5 mm-PP.5) were implanted in an onlay position in 21 New Zealand white rabbits. After 90 days of implantation the shrinkage, elasticity and foreign body reaction (FBR) were assessed.

RESULTS

The shrinkage of PP3 was 30.6 ± 4.3 %, PP1 49.3 ± 2.9 % and PP.5 49.5 ± 2.6 %. The shrinkage of PP3 was significantly lower (PP3 × PP1 p = 0.007, PP3 × PP.5 p = 0.005), PP1 and PP.5 were similar. The elasticity was similar. The strength of FBR in mesh pores was similar. The width of foreign body granuloma layers at the mesh-tissue interface was significantly reduced with increasing pore size (inner: PP3 10.1 ± 1.2; PP1 12.5 ± 2.9; PP.5 17.4 ± 5.2 and outer: PP3 21.2 ± 2.5; PP1 30.6 ± 6.3; PP.5 60.4 ± 14.9). All differences between the widths of granuloma layers were statistically significant (p < 0.010). One animal (PP1) was excluded because of a mesh infection.

CONCLUSIONS

Implantation of polypropylene mesh of a pore size of 3 mm in an onlay position is associated with a significant reduction of shrinkage in comparison to a 1 mm pore lightweight and 0.5 mm pore heavyweight mesh. A pore size increase to 3 mm is not sufficient for an improvement of mesh-tissue complex elasticity in comparison to a 1 mm pore lightweight and 0.5 mm heavyweight mesh. Polypropylene mesh with enlarged pores to 3 mm is associated with a similar strength of FBR in mesh pores and a reduced foreign body granuloma in comparison to a 1 mm pore lightweight and 0.5 mm pore heavyweight mesh.

Picrosirius red staining: a useful tool to appraise collagen networks in normal and pathological tissues

Specific staining of the extracellular matrix components is especially helpful in studying tissue remodeling, particularly in the case of connective tissue pathologies. As developed by Junqueira and colleagues in 1979, specific staining by Picrosirius red is one of the most important stains to study collagen networks in different tissues. Under polarized light, collagen bundles appear green, red or yellow, and are easily differentiated from the black background, thus allowing for quantitative morphometric analysis. As Junqueira and colleagues point out, many studies use color staining to differentiate collagen bundles and to specify collagen types, yet other studies report that polarized colors only reflect fiber thickness and packing. Using a simple histological example, our study illustrates the inability of Picrosirius red staining to differentiate collagen types, since the absorbed amount of polarized light by this dye strictly depends on the orientation of the collagen bundles.

Characterisation of the cellular infiltrate in the foreign body granuloma of textile meshes with its impact on collagen deposition

PURPOSE

As part of the foreign body reaction, mesh filaments are surrounded by an infiltrate of inflammatory cells. Though macrophages are considered as being predominant, little is known about the origin of other cells.

METHODS

On 55 meshes explanted from humans, we characterised the cells in the inflammatory infiltrate of the granuloma by immunohistochemistry using 10 cellular markers: CD3+ lymphocytes, CD4+ T helper cells, CD8+ cytotoxic T cells, CD20+ B lymphocytes, CD34+ stem cells, CD45R0+ leucocytes, CD68+ macrophages, Mib1 for proliferation, Vimentin for mesenchymal origin, and Desmin for myocytes. Collagen deposits were analysed after staining with Sirius Red.

RESULTS

More than 80 % of the cells in the infiltrate showed a positive expression of CD68, CD8, CD45R0 and Vimentin. CD4 and Desmin were seen in 30-80 % of the cells, unaffected by material or time. A score summarising the expression of all markers positively correlated significantly with an increased percentage of collagen type III (green) in the mesh wound. The analysis of collagen deposits was only affected to a small degree by size of area for investigation.

CONCLUSIONS

At the vicinity of the mesh filaments, the accumulated inflammatory cells represent a mixture of cells of various origins. The high expression of at least four markers requires co-expression of different surface markers and thus confirms the existence of multiple transition forms instead of dominance of just macrophages. This offers new options for interventions to attenuate the inflammatory reaction of mesh implants.

Postnatal testicular development in the Chinchilla rabbit

The Chinchilla rabbit is a breed with high commercial value and nowadays is increasingly used in various fields of biomedical research, however, its postnatal reproductive biology has been little studied. The aim of the present study was to investigate the postnatal development of the testis in this rabbit breed to determine both the proliferative periods and apoptosis. 30 rabbits aged 3-100 days old were used in the study. Determination of the period of differentiation of gonocytes to spermatogonia (50dpp), the periods of proliferation and apoptosis of their cells, as well as the beginning of spermatogenesis (60dpp) and the different stages of the seminiferous epithelium cycle were made. We found that these testicular developments were closer to that of humans when compared with rats, a species commonly employed in reproductive research. On comparing these results with those obtained from other breeds, there are clear differences favoring the use of this species as a research model in the field of male reproductive biology.