Anti-adhesive bioresorbable elastomer-coated composite hernia mesh that reduce intraperitoneal adhesions

Intraperitoneal adhesions (IAs) are a major complication arising from abdominal repair surgeries, including hernia repair procedures. Herein, we fabricated a composite mesh device using a macroporous monofilament polypropylene mesh and a degradable elastomer coating designed to meet the requirements of this clinical application. The degradable elastomer was synthesized using an organo-base catalyzed thiol-yne addition polymerization that affords independent control of degradation rate and mechanical properties. The elastomeric coating was further enhanced by the covalent tethering of antifouling zwitterion molecules. Mechanical testing demonstrated the elastomer forms a robust coating on the polypropylene mesh does not exhibit micro-fractures, cracks or mechanical delamination under cyclic fatigue testing that exceeds peak abdominal loads (50 N/cm). Quartz crystal microbalance measurements showed the zwitterionic functionalized elastomer further reduced fibrinogen adsorption by 73% in vitro when compared to unfunctionalized elastomer controls. The elastomer exhibited degradation with limited tissue response in a 10-week murine subcutaneous implantation model. We also evaluated the composite mesh in an 84-day study in a rabbit cecal abrasion hernia adhesion model. The zwitterionic composite mesh significantly reduced the extent and tenacity of IAs by 94% and 90% respectively with respect to uncoated polypropylene mesh. The resulting composite mesh device is an excellent candidate to reduce complications related to abdominal repair through suppressed fouling and adhesion formation, reduced tissue inflammation, and appropriate degradation rate.

The Therapeutic Potential of Targeting Key Signaling Pathways as a Novel Approach to Ameliorating Post-Surgical Adhesions

BACKGROUND

Peritoneal adhesions (PA) are a common complication of abdominal operations. A growing body of evidence shows that inhibition of inflammation and fibrosis at sites of peritoneal damaging could prevent the development of intra-abdominal adhesions.

METHODS

A search of PubMed, Medline, CINAHL and Embase databases was performed using the keywords 'postsurgical adhesion', 'post-operative adhesion', 'peritoneal adhesion', 'surgery-induced adhesion' and 'abdominal adhesion'. Studies detailing the use of pharmacological and non-pharmacological agents for peritoneal adhesion prevention were identified, and their bibliographies were thoroughly reviewed to identify further related articles.

RESULTS

Several signaling pathways, such as tumor necrosis factor-alpha, tissue plasminogen activator, and type 1 plasminogen activator inhibitor, macrophages, fibroblasts, and mesothelial cells play a key part in the development of plasminogen activator. Several therapeutic approaches based on anti-PA drug barriers and traditional herbal medicines have been developed to prevent and treat adhesion formation. In recent years, the most promising method to prevent PA is treatment using biomaterial-based barriers.

CONCLUSION

In this review, we provide an overview of the pathophysiology of adhesion formation and various agents targeting different pathways, including chemical agents, herbal agents, physical barriers, and clinical trials concerning this matter.

Perioperative Use of Antifibrotic Medications Associated With Lower Rate of Manipulation After Primary TKA: An Analysis of 101,366 Patients

BACKGROUND

Several commonly prescribed medications have known antifibrotic properties and have been shown to reduce postoperative scar formation in other clinical areas, but it is unknown whether the use of such medications perioperatively in patients undergoing TKA may improve rates of postoperative stiffness.

METHODS

A large US employer-sponsored healthcare database (Truven Marketscan) was queried for patients who underwent elective primary TKA for primary osteoarthritis between 2015-2019. Demographic information and comorbidities were recorded, along with whether patients were prescribed one of several medications with known antifibrotic properties during the three months before or after surgery.

RESULTS

Complete data were available for 101,366 patients undergoing TKA, of which 4,536 underwent MUA (4.5%). Perioperative use of any antifibrotic medication was associated with a lower likelihood of undergoing MUA (P < .001). When controlling for age, sex, comorbidities, opioid use, length of stay, among other variables, perioperative use of specific ACE inhibitors (OR 0.91, CI 0.84-1, P = .042), COX-2 inhibitors (OR 0.88, CI 0.81-0.96, P = .002), and angiotensin II receptor blockers, specifically losartan (OR 0.80, CI 0.70-0.91, P = .007) all remained significantly associated with lower rates of MUA.

CONCLUSION

This study, spanning over a hundred thousand primary TKA procedures over a recent five-year period, demonstrates an association between perioperative use of specific medications with antifibrotic properties and a decreased rate of MUA. These data will help inform future studies aimed to prospectively evaluate the potential of antifibrotic medications in preventing postoperative stiffness in high-risk patients undergoing knee arthroplasty.

Effect of intra-peritoneal induction of ascites fluid on the rate of postoperative intraabdominal adhesion in a rat model

Introduction

Intra-abdominal adhesions (IAAs) are secondary to peritoneal injuries such as previous surgery or intra-abdominal infections (IAIs). Accordingly, it is crucial to employ fitting techniques to minimize the likelihood of adhesions in any surgery. Due to a paucity of similar data available, this study sought to explore the effects of induced high serum ascites albumin gradient (SAAG) and low serum ascites albumin gradient (SAAG) on the rate of post-operative microscopic and macroscopic adhesion in a mouse model.

Material and methods

Sixty mice were compared in six groups of ten each. Control groups (1 &4) received normal saline, groups 2&5 received high SAAG ascites fluid, and groups 3&6 received low SAAG ascites fluid intraperitoneally. These groups underwent exploratory laparotomy on day zero, followed by the same procedure on the 10th (groups 1,2,3) and the 30th (Groups 4,5,6) day of surgery. Then, microscopic and macroscopic IAAs were evaluated. Data were analyzed in SPSS software and compared with a p-value less than 0.05.

Results

By comparison, the least microscopic and macroscopic IAAs after 10 and 30 days were found in the low SAAG ascites group. Revealing a statistically significant difference compared to the other two groups (P = 0.01). After 10 days of surgery, macroscopic IAA in the high SAAG group was significantly lower compared to the control and Low SAAG ascites groups.

Conclusion

Intraabdominal low SAAG ascites fluid can significantly decrease the probability of postoperative fibrosis and adhesion band formation.

Protocol number

IR. BUMS.REC.1399.503.

•

Regarding macroscopic adhesions 10 days and 30 days post laparotomy, low SAAG ascites had significantly prevented IAAs.

•

The least microscopic and macroscopic IAAs, 10 and 30 days after surgery, were found in the low SAAG ascites group.

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The results of reduced IAAs using low SAAG ascites can be beneficial to the primary prevention of postoperative adhesions.

Temperature-responsive biodegradable injectable polymers with tissue adhesive properties

Injectable polymers (IPs) exhibiting in situ hydrogel formation have attracted attention as vascular embolization and postoperative adhesion prevention materials. While utilizing hydrogels for such purposes, it is essential to ensure that they have appropriate and controllable tissue adhesion property, as it is crucial for them to not detach from their deposited location in the blood vessel or abdominal cavity. Additionally, it is important to maintain gel state in vivo for the desired period at such locations, where large amounts of body fluid exist. We had previously reported on a biodegradable IP system exhibiting temperature-responsive gelation and subsequent covalent cross-link formation. We had utilized triblock copolymers of aliphatic polyester and poly(ethylene glycol) (tri-PCGs) and its derivative containing acrylate group at the termini (tri-PCG-Acryl), exhibiting a longer and more controllable duration time of the gel state. In this study, the introduction of aldehyde groups by the addition of aldehyde-modified Pluronic (PL-CHO) was performed for conferring controllable and appropriate tissue adhesive properties on these IP systems. The IP systems containing PL-CHO, which were not covalently incorporated into the hydrogel network, exhibited tissue adhesive properties through Schiff base formation. The adhesion strength could be controlled by the amount of PL-CHO added. The IP system showed good vascular embolization performance and pressure resistance in the blood vessels. The IP hydrogel remained at the administration site in the abdominal space for 2 days and displayed effective adhesion prevention performance. STATEMENT OF SIGNIFICANCE: Injectable polymers (IPs), which exhibit in situ hydrogel formation, are expected to be utilized as vascular embolization and postoperative adhesion prevention materials. The tissue adhesion properties of hydrogels are important for such applications. We succeeded in conferring tissue adhesion properties onto a previously reported IP system by mixing it with Pluronic modified with aldehyde groups (PL-CHO). The aldehyde groups allowed for the formation of Schiff bases at the tissue surfaces. The tissue adhesion property could be conveniently controlled by altering the amount of PL-CHO. We revealed that the in vitro embolization properties of IPs in blood vessels could be substantially improved by mixing with PL-CHO. The IP system containing PL-CHO also exhibited good in vivo performance for postoperative adhesion prevention.

Effect of intra-abdominal administration of ascites fluid on postoperative peritoneal adhesion in rat model: A randomized controlled trail

Introduction

Intra-abdominal adhesions are typically found after the most surgical procedures. Normally, most adhesions are asymptomatic; however, few individuals experience postoperative adhesion-related problems such as small bowel obstruction, pelvic pain, infertility, or other complications. We aimed to evaluate the preventive effect of the ascites fluid for postoperative peritoneal adhesions in rat models.

Material and methods

This experimental trial was conducted in Sixty Syrian male rat randomly assigned to six groups of 10 animals each as follows: control (group 1&4); normal saline (group 2&5): 2 mL of normal saline was poured into the peritoneal cavity; and case (group 3&6): 2 mL ascites fluid was poured into the peritoneal cavity. All animals in the six groups underwent laparotomy and measurable serosal injury were created with a standard technique. 10 and 30 days after initial surgery, the rats underwent another laparotomy in groups 1, 2, 3 and 4, 5, 6, respectively to assess macroscopic and microscopic adhesions, which were scored by an examiner who was blind to the animals̕ group assignment. Data analyzed by SPSS version 18, using the kruskal Wallis and Bonferroni-corrected Mann-Whitney U tests. P-values of less than 0.05 were considered significant.

Results

The mean scores of both microscopic and macroscopic adhesion were significantly different between all the groups (P < 0.05). Total macroscopic and microscopic adhesion scores were significantly lower in the ascites fluid treatment than in the control (P = 0.0001) or the normal saline (P < 0.001) group. There was no significant difference between adhesion intensity 10 and 30 days after laparotomy (P > 0.05).

Conclusions

Ascites fluid can decrease the possibility of post-operative intraperitoneal adhesion formation.

•

Ascites fluid decreases post-operative adhesion formation.

•

The intensity of adhesion did not differ over time.

•

Ideal adhesion-reducing substances are still under investigation.

Postoperative Adhesion Prevention Using a Biodegradable Temperature-Responsive Injectable Polymer System and Concomitant Effects of the Chymase Inhibitor

Postoperative adhesion remains a problem in surgery and causes postoperative complications. Laparoscopic surgery is now common, making it increasingly important to develop injectable formulations of adhesion barriers that can be applied during such surgeries. Temperature-responsive injectable polymer (IP) systems exhibiting a sol-to-gel transition in response to temperature are promising candidates as effective adhesion barriers that can be applied conveniently during laparoscopic surgery. We previously developed IP systems exhibiting temperature-responsive irreversible gelation based on a triblock copolymer of poly(ε-caprolactone-co-glycolic acid) (PCGA) and poly(ethylene glycol) (PEG) (PCGA-b-PEG-b-PCGA: tri-PCG) and a tri-PCG derivative with acrylate groups at the termini (tri-PCG-acryl). A mixture of tri-PCG-acryl micelle solution and tri-PCG micelle solution containing polythiol exhibited an irreversible sol-to-gel transition in response to a temperature increase. The gel contains partial covalent cross-linking, and the degradation and physical properties of these IP hydrogels can easily be controlled by changing the mixing ratio of tri-PCG-acryl in the formulation. In this study, we investigated the effect of physical properties of the IP hydrogel on the efficacy of adhesion prevention using our IP system containing various amounts of tri-PCG-acryl. Our results show that an IP system with lower physical strength and rapid degradation reduces adhesion more effectively. Chymase plays a crucial role in exacerbating adhesion formation, and a peptide derivative-type chymase inhibitor (CI), Suc-Val-Pro-Phe^P(OPh)₂, was previously reported to prevent adhesion. We thus investigated the concomitant use of this CI with our IP system using two methods: separate administration of the CI and IP and entrapping the CI in the IP hydrogel. IP systems with separately administrated CI provided better results than the administration of an IP system entrapping the CI or sole IP systems. These findings suggest that the pharmacological effect of the CI and a physical barrier generated by our IP system effectively prevents adhesion.

Peritoneal adhesions: Occurrence, prevention and experimental models

Peritoneal adhesions (PA) are a postoperative syndrome with high incidence rate, which can cause chronic abdominal pain, intestinal obstruction, and female infertility. Previous studies have identified that PA are caused by a disordered feedback of blood coagulation, inflammation, and fibrinolysis. Monocytes, macrophages, fibroblasts, and mesothelial cells are involved in this process, and secreted signaling molecules, such as tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), tissue plasminogen activator (tPA), and type 1 plasminogen activator inhibitor (PAI-1), play a key role in PA development. There have been many attempts to prevent PA formation by anti-PA drugs, barriers, and other therapeutic methods, but their effectiveness has not been widely accepted. Treatment by biomaterial-based barriers is believed to be the most promising method to prevent PA formation in recent years. In this review, the pathogenesis, treatment approaches, and animal models of PA are summarized and discussed to understand the challenges faced in the biomaterial-based anti-PA treatments.

A novel coenzyme-Q approach for the prevention of postsurgical adhesion

Objectives

Postoperative intraperitoneal adhesions are an unsolved and important problem in abdominal surgery. In the present study, the probable preventive role of coenzyme-Q in the development of peritoneal adhesions was investigated.

Material and Methods

Sixteen Wistar Hannover male rats weighing 300-350 g were randomly separated into two groups of 8 rats each. The cecum was abraded with a sterile gauze until sub-serosal hemorrhage developed. A patch of peritoneum located opposite to the cecal abrasion was completely dissected. No treatment was given to Group 1. Group 2 received 30 mg/kg coenzyme-Q, which was injected 2 mL intraperitoneally. All the rats were sacrificed on the postoperative 21^st day, and after adhesions were scored macroscopically, tissue specimens of the peritoneum and bowel were subjected to histopathological investigation. Tissue and blood specimens were also taken for biochemical analysis to investigate antioxidant efficiency.

Results

Adhesion scores were significantly different between the control group and the coenzyme-Q group (p= 0.001). According to the tissue levels of GSH-Px, MDA, and SOD levels, there was no significant difference between the study groups (p= 0.074, p= 0.208, p= 0.526). According to the plasma GSH-Px and SOD levels, there was significant difference between the groups (p= 0.002, p= 0.001), but the difference was not significant at MDA levels (p= 0.793). The differences between the pathological scores of the control and coenzyme-Q (p= 0.028 for fibrosis; p= 0.025 for inflammation) groups were statistically significant.

Conclusion

This study confirms that coenzyme-Q is the potential application in the prevention of early postoperative adhesions.

Synthetic surgical meshes used in abdominal wall surgery: Part I-materials and structural conformation

Surgical implants are commonly used in abdominal wall surgery for hernia repair. Many different prostheses are currently offered to surgeons, comprising permanent synthetic polymer meshes and biologic scaffolds. There is a wide range of synthetic meshes currently available on the market with differing chemical compositions, fiber conformations, and mesh textures. These chemical and structural characteristics determine a specific biochemical and mechanical behavior and play a crucial role in guaranteeing a successful post-operative outcome. Although an increasing number of studies report on the structural and mechanical properties of synthetic surgical meshes, nowadays there are no consistent guidelines for the evaluation of mechanical biocompatibility or common criteria for the selection of prostheses. The aim of this work is to review synthetic meshes by considering the extensive bibliography documentation of their use in abdominal wall surgery, taking into account their material and structural properties, in Part I, and their mechanical behavior, in Part II. The main materials available for the manufacture of polymeric meshes are described, including references to their chemical composition, fiber conformation, and textile structural properties. These characteristics are decisive for the evaluation of mesh-tissue interaction process, including foreign body response, mesh encapsulation, infection, and adhesion formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 689-699, 2017.

Adhesive small bowel obstruction after laparotomy during infancy

Background

Intra-abdominal adhesions can cause adhesive small bowel obstruction, chronic abdominal pain and female infertility. Reports on long-term outcomes following laparotomy during infancy are scarce. The aims of this study were to investigate the incidence of and risk factors for long-term adhesive small bowel obstruction and associated morbidity after laparotomy during infancy.

Methods

Infants who underwent laparotomy between 1976 and 2011 were identified. Data were extracted from medical records and a questionnaire was sent to the patients.

Results

Some 898 of 1185 eligible patients were included, with a median follow-up time of 14·7 (range 0·0–36·0) years. Median age at first laparotomy was 6 (range 1·0–365·0) days. There were 113 patients (12·6 per cent) with adhesive small bowel obstruction who underwent relaparotomy, 79 (69·9 per cent) occurring during the first 2 years after the initial laparotomy. The highest incidence of small bowel obstruction was found in patients with Hirschsprung's disease (19 of 65, 29 per cent), malrotation (13 of 45, 29 per cent), intestinal atresia (11 of 40, 28 per cent) and necrotizing enterocolitis (16 of 64, 25 per cent). Lengthy duration of surgery (hazard ratio (HR) 1·25, 95 per cent c.i. 1·07 to 1·45), stoma formation (HR 1·72, 1·15 to 2·56) and postoperative complications (HR 1·81, 1·12 to 2·92) were independent risk factors. Chronic abdominal pain was reported in 180 (24·0 per cent) of 750 patients, and 17 (13·8 per cent) of 123 women reported infertility.

Conclusion

The incidence of adhesive small bowel obstruction after laparotomy in infants is high.

A-Part Gel, an adhesion prophylaxis for abdominal surgery: a randomized controlled phase I-II safety study [NCT00646412]

Background

Intra-abdominal surgical intervention can cause the development of intra-peritoneal adhesions. To reduce this problem, different agents have been tested to minimize abdominal adhesions; however, the optimal adhesion prophylaxis has not been found so far. Therefore, the A-Part^® Gel was developed as a barrier to diminish postsurgical adhesions; the aim of this randomized controlled study was a first evaluation of its safety and efficacy.

Methods

In this prospective, controlled, randomized, patient-blinded, monocenter phase I–II study, 62 patients received either the hydrogel A-Part-Gel^® as an anti-adhesive barrier or were untreated after primary elective median laparotomy. Primary endpoint was the occurrence of peritonitis and/or wound healing impairment 28 ± 10 days postoperatively. As secondary endpoints anastomotic leakage until 28 days after surgery, adverse events and adhesions were assessed until 3 months postoperatively.

Results

A lower rate of wound healing impairment and/or peritonitis was observed in the A-Part Gel^® group compared to the control group: (6.5 vs. 13.8 %). The difference between the two groups was −7.3%, 90 % confidence interval [−20.1, 5.4 %]. Both treatment groups showed similar frequency of anastomotic leakage but incidence of adverse events and serious adverse events were slightly lower in the A-Part Gel^® group compared to the control. Adhesion rates were comparable in both groups.

Conclusion

A-Part Gel^® is safe as an adhesion prophylaxis after abdominal wall surgery but no reduction of postoperative peritoneal adhesion could be found in comparison to the control group. This may at least in part be due to the small sample size as well as to the incomplete coverage of the incision due to the used application.

Trial Registration: NCT00646412

Berberine hydrochloride prevents postsurgery intestinal adhesion and inflammation in rats

Intestinal adhesion, characterized by connection of the loops of the intestine with other abdominal organs by fibrous tissue bands, remains an inevitable event of abdominal operations and can cause a number of complications. Berberine hydrochloride (berberine), a natural plant alkaloid derived from Chinese herbal medicine, is characterized by diverse pharmacological effects, such as anticancer and lower elevated blood glucose. This study is designed to investigate the effects of berberine on adhesion and inflammation after abdominal surgeries and the underlying molecular mechanisms. Adhesion severity grades and collagen deposition were assessed 14 days after surgery. We evaluated the levels of intercellular adhesion molecule-1 (ICAM-1) and inflammatory cytokines interleukin-1β (IL-1β), IL-6, transforming growth factor β (TGF-β), tumor necrosis factor-α (TNF-α), and examined transforming growth factor-activated kinase 1 (TAK1)/c-Jun N-terminal kinase (JNK) and TAK1/nuclear factor κB (NF-κB) signaling. The surgery group experienced the most severe adhesions, and berberine strikingly reduced the density and severity of adhesion. Results showed significant lower expression of IL-1β, IL-6, TGF-β, TNF-α, and ICAM-1, in berberine groups compared with the operation group. Activities of phosphorylated JNK and phosphorylated NF-κB were inhibited in the berberine groups compared with the surgery group. Our novel findings identified berberine hydrochloride as a promising strategy to prevent adhesion by downregulating ICAM-1 and reduce inflammation by inhibiting the TAK1/JNK and TAK1/NF-κB signaling after abdominal surgery, which brought out a good therapeutic approach for the development of clinical application for postoperative abdominal adhesion and inflammation.

Tensile strength after closure of mesenteric gaps in laparoscopic gastric bypass: three techniques tested in a porcine model

BACKGROUND

Internal hernias occur frequently after laparoscopic gastric bypass. We have found no data on the relative strength of the various techniques available for closing these defects. The present study was performed to obtain such data to form a theoretical basis for clinical studies.

METHODS

Six piglets were operated laparoscopically and four loops of small bowel created in each. These mesenteric gaps were closed over a distance of 40 mm using (1) running 2-0 Ethibond® suture, (2) Endo Hernia stapler, (3) fibrin glue (Tisseel®) and (4) controls, where the mesenteric surfaces were rubbed with a sponge and approximated without further intervention. After 6 weeks, the different segments of the mesentery were excised. The tensile strength was measured using continuously increased traction until the closure ruptured. The ordinary mesentery served as the control. The breaking tension and total amount of energy transferred to the tissue were registered.

RESULTS

Control areas with rubbed areas developed no adhesions. Suture and staple lines contracted by 30 % in length, whereas the fibrin glued lines were even shorter. Median tensile strength was greatest for the sutured lines (14,293 mN) and stapled lines (10,798 mN). Fibrin glued lines were significantly weaker (6,780 mN, p = 0.013 and p = 0.026), but as strong as ordinary mesentery (4,165 mN).

CONCLUSIONS

If ongoing controlled randomized trials show closure to be beneficial, further studies should include staples as one of the options for the closure of mesenteric defects. The role of fibrin glue needs to be further investigated.

Ventralight ST and SorbaFix versus Physiomesh and Securestrap in a porcine model

BACKGROUND AND OBJECTIVES

The objective of this study was to compare mesh contracture, adhesion characteristics, tissue ingrowth, and histologic response of Ventralight ST/SorbaFix (C.R. Bard/Davol, Warwick, RI, USA) with Physiomesh/Securestrap (Ethicon, Somerville, NJ, USA) in a porcine model of laparoscopic ventral hernia repair.

METHODS

Standard laparoscopic technique was used to bilaterally implant meshes in 10 female Yorkshire swine. Each animal received either two Ventralight ST meshes (oval shaped, 10.2 × 15.2 cm) or two Physiomesh meshes (oval shaped 10 × 15 cm), one on either side of the midline. The meshes were fixated to the intact peritoneum with either SorbaFix (for animals receiving Ventralight ST) or Securestrap (for animals receiving Physiomesh). There were 5 animals in each group, yielding 10 of each meshfixation combination. Mesh contracture, adhesion characteristics, tissue ingrowth, and histologic response were evaluated after 14 days by image analysis, mechanical testing, and histologic staining (hematoxylin-eosin, Masson trichrome, picrosirius red, and von Willebrand factor).

RESULTS

Ventralight ST/SorbaFix and Physiomesh/Securestrap exhibited a similar percentage of mesh contracture, percentage of adhesion coverage, adhesion tenacity, collagen deposition, and levels of necrosis (P > .05 in all cases). However, Ventralight ST/SorbaFix exhibited significantly less inflammation (P = .0001), fibrosis (P = .0017), hemorrhage (P = .0001), and angiogenesis (P = .0032) and significantly greater strength of tissue ingrowth (P = .0003) than Physiomesh/Securestrap after the 14-day implantation period.

CONCLUSIONS

Ventralight ST/SorbaFix exhibited more favorable strength of tissue ingrowth and histologic response and similar mesh contracture and adhesion characteristics compared with Physiomesh/Securestrap over a short-term 14-day implantation period in a preclinical porcine model.

Novel powdered anti-adhesion material: preventing postoperative intra-abdominal adhesions in a rat model

BACKGROUND

Although laparoscopic surgery has decreased postoperative adhesions, complications induced by adhesions are still of great concern. The aim of this study was to investigate the anti-adhesive effects of a novel powdered anti-adhesion material that can be applied during laparoscopic surgery in comparison with other anti-adhesion materials.

METHODS

Our novel powdered anti-adhesion material is composed of aldehyde dextran and ε-poly(L-lysine). In 40 male rats, a 2.5×2.0-cm abdominal wall resection and cecum abrasion were performed. The rats were randomized into four groups based on the anti-adhesion treatments: normal saline; Seprafilm(®); Interceed(®); and novel powdered anti-adhesion material. The animals were euthanized on days 7 and 28 to evaluate the adhesion severity, area of adhesion formation, gross appearance, and pathological changes.

RESULTS

The adhesion severities on both days 7 and 28 were significantly lower for all anti-adhesion material groups compared with the normal saline group (p<0.05). Pathologically, all groups showed inflammatory cell infiltration on day 7 and complete regeneration of the peritoneum on day 28.

CONCLUSIONS

Our novel powdered anti-adhesion material was found to be effective for reducing postoperative intra-abdominal adhesions and showed equivalent efficacy to commercial anti-adhesion materials.

Cell-cell and cell-matrix dynamics in intraperitoneal cancer metastasis

The peritoneal metastatic route of cancer dissemination is shared by cancers of the ovary and gastrointestinal tract. Once initiated, peritoneal metastasis typically proceeds rapidly in a feed-forward manner. Several factors contribute to this efficient progression. In peritoneal metastasis, cancer cells exfoliate into the peritoneal fluid and spread locally, transported by peritoneal fluid. Inflammatory cytokines released by tumor and immune cells compromise the protective, anti-adhesive mesothelial cell layer that lines the peritoneal cavity, exposing the underlying extracellular matrix to which cancer cells readily attach. The peritoneum is further rendered receptive to metastatic implantation and growth by myofibroblastic cell behaviors also stimulated by inflammatory cytokines. Individual cancer cells suspended in peritoneal fluid can aggregate to form multicellular spheroids. This cellular arrangement imparts resistance to anoikis, apoptosis, and chemotherapeutics. Emerging evidence indicates that compact spheroid formation is preferentially accomplished by cancer cells with high invasive capacity and contractile behaviors. This review focuses on the pathological alterations to the peritoneum and the properties of cancer cells that in combination drive peritoneal metastasis.

A review of the composition, characteristics, and effectiveness of barrier mesh prostheses utilized for laparoscopic ventral hernia repair

BACKGROUND

The objective of this review was to provide an overview of the components that comprise each of the eight barrier mesh prostheses commonly utilized for LVHR and to review the current literature related to the characteristics and effectiveness of these materials to guide the general surgeon in selecting the most appropriate material for LVHR.

METHODS

Composite prostheses with permanent barriers (Bard™ Composix™ E/X, Bard™ Composix™ L/P, and DUALMESH(®) Biomaterial) were compared to composite prostheses with absorbable barriers (C-QUR™ Mesh, PROCEED™ Surgical Mesh, Bard™ Sepramesh™ IP Composite, Parietex™ Composite, and PHYSIOMESH™) using scanning electron microscopy and a review of the current preclinical and clinical literature.

RESULTS

Clinical studies and preclinical animal models have attempted to determine the adhesion characteristics and effectiveness of barrier mesh prostheses available for ventral hernia repair applications. However, it is difficult to make any definitive statements about the adhesion characteristics and effectiveness of these materials because all meshes were not included in all studies and likewise not compared under identical conditions. Overall, Parietex™ Composite and DUALMESH(®) Biomaterial were cited most frequently for improvement of adhesion characteristics, followed closely by Bard™ Sepramesh™ IP Composite and C-QUR™ Mesh. Bard™ Composix™, PROCEED™ Surgical Mesh, and uncoated polypropylene were cited most frequently as having the most tenacious and extensive adhesions.

CONCLUSIONS

Differences observed between the various barrier prostheses are likely attributable to the chemical composition of the barrier or the conditions required for resorption and metabolism of the barrier components. It is likely that the components of these barriers incite a wide range of inflammatory responses resulting in the range of adhesion coverage and tenacity observed in the preclinical and clinical studies reviewed. Clinical trials are needed to more appropriately define the clinical effectiveness of these barriers.

A hydrogel for adhesion prevention: characterization and efficacy study in a rabbit uterus model

OBJECTIVE

Postoperative peritoneal adhesions following gynaecological surgery remain a clinically relevant problem. One approach to prevent adhesion formation is to apply physical barriers such as hydrogels.

STUDY DESIGN

A physically crosslinked polyvinyl alcohol and carboxymethylcellulose (PVA/CMC) hydrogel (A-Part) was characterized in vitro. Three different traumatization methods were evaluated in a rabbit uterine study. To determine its anti-adhesion efficacy, the hydrogel was first tested in an in vivo pilot study and then in a larger trial to compare it with icodextrin 4% solution (Adept) and controls.

RESULTS

Rheological measurements showed an increased elasticity of the hydrogel after freezing. In vivo experiments revealed a clear reduction in incidence, extent and severity of adhesions compared to the icodextrin 4% solution and the untreated control group.

CONCLUSIONS

These results warrant further investigation of the PVA/CMC A-Part hydrogel in clinical trials focused on gynaecological procedures.

Physicomechanical evaluation of absorbable and nonabsorbable barrier composite meshes for laparoscopic ventral hernia repair

BACKGROUND

This study aimed to compare the physicomechanical properties of composite prostheses for laparoscopic ventral hernia repair (LVHR) through standard testing and a proposed classification system.

METHODS

Seven prostheses (four with absorbable barriers and 3 with nonabsorbable barriers) were evaluated. The barrier layer was removed, after which the area of the interstices and the diameter of the filaments were determined. The barrier layer was left intact during thickness, density, suture retention strength, tear resistance, uniaxial tensile, and ball-burst testing. Specimens were oriented parallel or perpendicular to their longest dimension during testing. One-way analysis of variance (ANOVA) with Tukey's posttest or an unpaired, two-tailed t-test was performed to determine whether differences existed due to mesh or orientation, and a p value<0.05 was considered significant.

RESULTS

Significant differences were observed between mesh types and due to the orientation of the mesh during testing. Of the absorbable barrier meshes, Bard Sepramesh IP Composite demonstrated the greatest suture retention and tear strengths, followed by C-QUR mesh. Of the permanent barrier meshes, DUALMESH demonstrated the greatest suture retention strength in the perpendicular direction, followed by Bard Composix E/X. DUALMESH and Bard Composix E/X demonstrated equivalent suture retention strength in the parallel direction and equivalent tear resistance in both testing directions. All meshes demonstrated tensile strengths greater than the physiologically relevant range of 16-32 N/cm.

CONCLUSIONS

This study provided a basic understanding of how the structural aspects of each mesh design influence functionality. Differences between composite barrier prostheses commonly used for LVHR were observed due to barrier type, mesh type, and orientation. A set of standard testing techniques and a classification system also were presented to define fully the properties of these materials.

An assessment of the effects of a hyaluronan-based solution on reduction of postsurgical adhesion formation in rats: a comparative study of hyaluronan-based solution and two film barriers

BACKGROUND

Intra-abdominal application of anti-adhesive barriers may reduce the extent and severity of postoperative adhesions. This study was designed to compare the effectiveness of a sprayable liquid barrier (a mixed solution of sodium hyaluronate and carboxymethylcellulose) with two conventional sheets.

METHODS

Eighty male Sprague Dawley rats underwent laparotomy with subsequent multiple intestinal wall abrasions and abdominal wall injury. Afterwards, sodium hyaluronate and carboxymethylcellulose (HA-CMC) solutions were intraperitoneally sprayed or a film barrier of either oxidized regenerated cellulose (ORC) or polylactic acid (PA) was placed under the incision. At postoperative d 21, the rats underwent relaparotomy and complete adhesiolysis. Three investigators, who were blind to the group assignment, scored the extent of adhesion formation and resected specimens for histologic examination of fibrosis and inflammation. Expression profiles of parameters as mediators (macrophages [CD68]) in cellular inflammation response were analyzed.

RESULTS

Mean adhesion scores in rats that received HA-CMC solution (7.6±2.3) and ORC membrane (8.1±2.2) were lower than in rats that received PA film (10.7±2.5) and the control group (11.2±2.6) (P<0.05 for each comparison). In addition, there were significantly fewer adhesions located between large and small intestine in the HA-CMC solution group than in the control and each of the film barrier groups (P<0.05 for each comparison).

CONCLUSIONS

This study suggests that both HA-CMC solution and ORC membrane decrease the overall incidence of postoperative adhesions. However, the mixed solution of HA-CMC appeared to be superior to ORC membrane because this sprayable solution is easy to use and suitable for site-specific adhesion prevention after multifocal bowel trauma.

Complications due to adhesion formation following cesarean sections: a review of deliveries in three cases

OBJECTIVE

To describe complications due to adhesion formation following cesarean sections and methods to prevent adhesion formation.

DESIGN

Case reports.

SETTING

Labor and delivery suites in three hospitals.

PATIENT(S)

[1] A 32-year-old G2P1 undergoing a repeat cesarean section with severe adhesions and subsequent bladder injury and repair. [2] A 36-year-old G3P1 undergoing a vaginal birth after cesarean (VBAC) with partial uterine dehiscence, fetal distress, and dense pelvic adhesions. [3] A 38-year-old G4P2 undergoing repeat cesarean section with dense adhesions from the uterus to the anterior abdominal wall.

INTERVENTION(S)

Cesarean sections, lysis of adhesions, and cystotomy repair.

RESULT(S)

All three patients had significant complications and sequelae secondary to dense uterine adhesions from previous cesarean sections.

CONCLUSION(S)

Adhesion prevention measures should be routinely implemented to reduce adhesion formation after cesarean deliveries and thus decrease corresponding sequelae. Critical steps to decrease adhesion formation include practicing meticulous surgical techniques, gentle tissue handling, minimizing ischemia and desiccation, controlling hemostasis, avoiding powdered gloves, and achieving peritoneal closure. Based on available data, adhesion barriers are effective in preventing or reducing adhesions after gynecologic surgery and have also been effective following cesarean sections.

An FDA approved neurokinin-1 receptor antagonist is effective in reducing intraabdominal adhesions when administered intraperitoneally, but not orally

INTRODUCTION

Postoperative adhesions pose a continued healthcare problem. We previously demonstrated that intraperitoneal (i.p.) administration of a neurokinin-1 receptor antagonist (NK-1RA) at surgery reduces intraabdominal adhesions in rats. The NK-1RA aprepitant (Emend, Merck) is clinically approved for preventing postoperative nausea and vomiting; however, its effects on adhesion formation are unknown. Thus, we determined the effects of i.p. and oral administration of aprepitant on adhesion formation in a rat model.

METHODS

Adhesions were surgically induced in rats that were randomized to receive either one or five oral preoperative doses or a single intraoperative i.p. dose of aprepitant (50 mg/kg). Adhesions were scored at 7 days. In similar experiments using i.p. dosing, animals were sacrificed at 24 h and peritoneal fluid, and tissue were collected to assess fibrinolytic activity and tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) mRNA levels, respectively.

RESULTS

I.p. aprepitant reduced adhesion formation by 33% (p < 0.05) compared with controls while oral aprepitant had no effect. Compared to controls i.p. aprepitant reduced tPA activity by 55% (p < 0.05), increased PAI-1 mRNA levels by 140% (p < 0.05), and had no affect on tPA mRNA levels.

CONCLUSION

These data suggest that aprepitant maybe a useful pharmacologic agent for reducing adhesion formation clinically.