Postoperative adhesion prevention using a statin-containing cellulose film in an experimental model

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

Curcumin polymeric membranes for postoperative peritoneal adhesion: Comparison of nanofiber vs. film and phospholipid-enriched vs. non-enriched formulations

Intra-abdominal adhesion remains a major postoperative problem and is able to place individuals at lifelong risk of serious complications. Among available approaches, insertion of a barrier membrane at the site of injury partially inhibited adhesion formation. Moreover, the local administration of an anti-adhesive agent showed some favorable effects. In this study, we aimed to prepare and fully characterize polycaprolactone (PCL)-based film casts and electrospun nanofibers (NFs) containing a natural anti-inflammatory agent, curcumin (CUR), with extended-release properties. We also compared their efficiencies in preventing tissue adhesions. Additionally, the impact of soy phosphatidylcholine (SPC) enrichment on adhesion prevention was investigated. Prepared membranes were evaluated in terms of surface morphology (SEM, AFM), surface wettability, CUR release profiles, structural properties (FTIR, XRD, DSC), and mechanical behaviors. To further analyze the anti-adhesion effectiveness, a cecal abrasion model was performed on rats. SEM and AFM images showed a smoother surface in SPC-containing films. Concerning NFs, uniform bead-free fibers were observed and SPC containing NFs showed higher conductivity and lower viscosity and therefore, smaller fibers. All formulations exhibited sustained drug release over 4 weeks. In vivo findings revealed the superior performance of films compared to NFs and phospholipid-enriched formulations over non-enriched ones. Among all film formulations and in comparison to the positive control (Seprafilm®), CUR-SPC-PCL films significantly reduced peritoneal adhesions, as evidenced by gross examination, histological evaluation and immunohistochemical (IHC) analysis. The remarkable in vivo anti-adhesion activity together with suitable in vitro properties have made CUR-SPC-PCL films a promising system for postoperative anti-adhesion purposes in the clinic.

Prevention of abdominal adhesion by a polycaprolactone/phospholipid hybrid film containing quercetin and silver nanoparticles

Aim: To develop quercetin-loaded poly(caprolactone) (PCL)/soybean phosphatidylcholine (PC) films coated with silver (Ag) to prevent the formation of postoperative adhesions (POA). Materials & methods: Films were prepared using the solvent casting method, coated with Ag, and underwent in vitro tests. In vivo studies were conducted employing an animal model of sidewall defect and cecum abrasion. Results: Films showed sustained release behavior of quercetin and Ag. Coating films with Ag improved their antimicrobial activity. In vivo studies confirmed superior antiadhesion properties of films compared with the control groups evaluated by gross observation, histochemical staining and immunohistochemistry analyses. Conclusion: Ag-Q-PCL-PC films are a potential candidate to prevent POA by acting as a sustained release delivery system and physical barrier.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

The potential association between metabolic syndrome and risk of post-surgical adhesion

Metabolic syndrome (MetS) is defined by the clustering of several associated with a group of disorders that include: obesity, dyslipidemia, hypertension, and insulin resistance. The incidence of MetS is increasing globally around the world. Indeed the rates of different types of surgery in older or younger patients with Mets are increasing and they are exposed to a wide range of operations including abdominal, pelvic, urologic, or any invasive procedures. Post-surgical adhesion is a common problem and is a challenge for the surgeon. Despite many studies on its pathogenesis, there remain many un-answered questions about it, for example why certain tissues and patients are more at higher risk of post-surgical adhesions. Many studies have suggested that MetS is associated with up-regulating molecular mechanisms leading to chronic inflammation and hypercoagulability. In this review, we discuss some of the molecular mechanisms by MetS may enhance post-surgical adhesion, and particularly regarding those involved in coagulation and inflammation.

Effect of statins on experimental postoperative adhesion: a systematic review and meta-analysis

Adhesion is a significant concern after surgery. Many researchers studied the anti-adhesive effect of statin, of which results were inconsistent. Thus, we purposed to perform a systematic review and meta-analysis to evaluate the effect of statins on postoperative adhesion in an experimental study. A comprehensive search was conducted using MEDLINE, EMBASE, and Google Scholar to identify animal studies that investigated the postoperative anti-adhesive effect of statins applied at the surgical area. Primary outcome measure was gross adhesion score. Secondary outcomes included microscopic adhesion score and tissue plasminogen activator (t-PA) activity. Totally, 298 rats from 9 animal studies (172 rats received statin therapy and 126 rats received placebo or no treatment) were included in the final analysis. The combined results showed that gross and microscopic adhesion scores were significantly lower in the statin group in comparison to the control group (standardized mean difference [SMD] = 1.65, 95% confidence interval [CI]: 1.02 to 2.28, P_chi² < 0.001, I² = 77.9%; SMD = 1.90, 95% CI: 1.10 to 2.79, P_chi² < 0.001, I² = 84.5%, respectively). However, there was no evidence of a difference in t-PA activity (SMD = -3.43, 95% CI: -7.95 to 1.09, P_chi² < 0.001, I² = 95.5%). In conclusion, statins were effective in preventing postoperative adhesion, as assessed based on gross and microscopic adhesion scores in rats.

Prospective mixed-methods study of patients undergoing relaparotomy (ReLap study; DRKS00013001)

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Patients undergoing relaparotomies are underrepresented in clinical trials.

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The study has three steps: health care research, translational research, and RCT.

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The clinical course will be followed prospectively.

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Main outcomes are postoperative complications, incisional hernias and adhesions.

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The ReLap study will gain evidence for best care in relaparotomies.

Background

Patients undergoing relaparotomies are underrepresented in clinical trials. Standard of care, relative outcomes compared to primary laparotomy, and the ideal fascial closure technique are unknown.

Objective

The ReLap study has three objectives: First, to determine standard of care and gain evidence of intra-/postoperative outcomes for patients undergoing relaparotomy compared to patients undergoing primary laparotomy. Second, to gain evidence of an association between biomarkers and adhesion grade in a clinical-translational approach in patients undergoing relaparotomy or primary laparotomy. Third, to gain evidence of the feasibility and comparative effectiveness of fascial closure after relaparotomy using the small stitches technique with Monomax 2–0 versus the large stitches technique with PDS 1 loop.

Methods

The ReLap study is a monocentric, prospective, mixed-methods, exploratory study with three steps: health care research, translational research, and randomized controlled trial. All patients scheduled for elective laparotomies or relaparotomies at the University of Heidelberg will be screened for eligibility. There will be five study visits during the hospital stay and one study visit one year after surgery. The clinical course will be followed and outcomes necessary to answer the study objectives will be captured prospectively. Relaparotomy patients eligible for closure with the small and large stitches technique will be randomized intraoperatively to one technique.

Discussion

The ReLap study will bridge a significant knowledge gap regarding patients undergoing relaparotomy. Differences in the standard of care between relaparotomies and primary laparotomies will be determined. The relation between biomarkers and manifestation of adhesions will be explored and evidence for the comparative effectiveness of fascial closure after relaparotomy will be gained.

Intraperitoneal administration of rosuvastatin prevents postoperative peritoneal adhesions by decreasing the release of tumor necrosis factor

Objectives

The purpose of this experimental study was to demonstrate the reduction of peritoneal adhesions formation in rats after intraperitoneal administration of rosuvastatin, due to its anti-inflammatory effect.

Method

Peritoneal adhesions were induced in 120 Wistar-Bratislava rats divided into 4 groups (n=30), using a parietal and visceral (cecal) abrasion model. Group I was designated as control group; in group II, a saline solution was administered intraperitoneally; in groups III and IV, a single dose of rosuvastatin solution, 10 mg/kg and 5 mg/kg respectively, was injected intraperitoneally. The serum values of tumor necrosis factor (TNF-α) and interleukin-1 (IL-1α) were determined on day 1 and day 7 postoperatively (ELISA). Macroscopic assessment of the peritoneal adhesions was conducted on day 14.

Results

Rosuvastatin therapy induced a significant decrease of tumor necrosis factor serum levels in groups III and IV, on day 1 and day 7 (p<0.01). Intraperitoneal administration of rosuvastatin correlated with a decrease of mean interleukin-1α levels on postoperative day 1 in groups III (p=0.0013) and IV (p=0.00011), but not on day 7, where the differences were no longer statistically significant (p=0.8) The reduction of postoperative peritoneal adhesions in the experimental rat model is supported by the anti-inflammatory effect of rosuvastatin, mediated mainly by the tumor necrosis factor.

Conclusions

Rosuvastatin prevents the formation of postoperative peritoneal adhesions in rats. This effect may be linked to the inhibition of proinflammatory cytokines release in the early stages of adhesions formation. The present study suggests that rosuvastatin may be an efficient pharmacological agent in the prevention of postoperative peritoneal adhesions development, and requires further studies as it has a promising application value.

Therapeutic Roles of Statins in Gynecology and Obstetrics: The Current Evidence

INTRODUCTION

Statins are a class of drugs, which act by inhibiting the rate-limiting enzyme of cholesterol biosynthesis (3-hydroxy-3-methyl-glutaryl-CoA reductase). The inhibition of mevalonate synthesis leads to subsequent inhibition of downstream products of this pathway, which explains the pleiotropic effects of these agents in addition to their well-known lipid-lowering effects. Accumulating evidence suggests that statins might be beneficial in various obstetric and gynecologic conditions.

METHODS

Literature searches were performed in PubMed and EMBASE for articles with content related to statins in obstetrics and gynecology. The findings are hereby reviewed and discussed.

RESULTS

Inhibition of mevalonate pathway leads to subsequent inhibition of downstream products such as geranyl pyrophosphate, farnesyl pyrophosphate, and geranylgeranyl pyrophosphate. These products are required for proper intracellular localization of several proteins, which play important roles in signaling pathways by regulating membrane trafficking, motility, proliferation, differentiation, and cytoskeletal organization. The pleiotropic effects of statins can be summarized in 4 categories: antiproliferative, anti-invasive, anti-inflammatory, and antiangiogenic. The growing body of evidence is promising for these agents to be beneficial in endometriosis, polycystic ovary syndrome, adhesion prevention, ovarian cancer, preeclampsia, and antiphospholipid syndrome. Although in vivo studies showed varying degrees of benefit on fibroids and preterm birth, appropriately designed clinical trials are needed to make definitive conclusions.

CONCLUSION

Statins might play a role in the treatment of endometriosis, polycystic ovary syndrome, adhesion prevention, ovarian cancer, preeclampsia, and antiphospholipid syndrome.

A Time Course of Bevacizumab (Anti-VEGF) Effect on Rat Peritoneum: Relations Between Antiadhesive Action and Fibrin Regulation Enzymes

BACKGROUND

To investigate the early and late antiadhesive effect and any changes of fibrin matrix regulation enzymes on rat peritoneum, after local administration of bevacizumab.

METHODS

Rats were subjected to cecal abrasion. Bevacizumab (5 mg/kg) against placebo was given intraperitoneally. On the 2nd, 14th, and 28th postoperative days adhesions were scored, and tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), matrix metalloproteinase-9 (MMP-9), degree of fibrosis, and angiogenesis were measured in abrased cecum and in intact parietal peritoneum.

RESULTS

Bevacizumab significantly reduced adhesions up to 15% on the 2nd, 52.5% on the 14th, and 55% on the 28th postoperative day, and significantly increased tPA concentrations in peritoneum. PAI-1 was decreased, and a significantly higher tPA/PAI-1 ratio along with an increase of MMP-9 was measured at all time points. Fibrosis and angiogenesis were significantly lower on the 14th and 28th postoperative days.

CONCLUSIONS

Local bevacizumab administration has a strong early and late antiadhesive action on rat peritoneum, mediated by changes in the tPA/PAI-1 and MMP balance in favor of fibrinolysis up to 28 days after operations.

Evaluation of the Effectiveness of Peritoneal Adhesion Prevention Devices in a Rat Model

BACKGROUND

Abdominal operations are followed by adhesions, a prevalent cause of abdominal pain, and the most frequent cause for bowel obstruction and secondary female infertility. This rat study addresses adhesion prevention capability of Adept(®), Interceed(®), Seprafilm(®), and a novel device, 4DryField(®) PH which is provided as powder and generates its effect as gel.

METHODS

Sixty-eight male Lewis rats had cecal abrasion and creation of an equally sized abdominal wall defect, and were grouped randomly: A control group without treatment (n=10); two groups treated with 4DryField(®) PH using premixed gel (n=15) or in-situ gel technique (n=16); one group each was treated with Seprafilm(®) (n=8), Interceed(®) (n=9), or Adept(®) (n=10). Sacrifice was on day 7 to evaluate incidence, quality, and quantity of adhesions, as expressed via adhesion reduction rate (AR). Histologic specimens were evaluated. Statistical analyses used ANOVA and unpaired t-tests.

RESULTS

4DryField(®) PH significantly reduced incidence and severity of adhesions both as premixed gel (AR: 85.2%) and as in-situ made gel (AR: 100%), a comparison between these two application techniques showed no differences in efficacy. Seprafilm(®) did not reduce incidence but severity of adhesions significantly (AR: 53.5%). With Interceed(®) (AR: 3.7%) and Adept(®) (AR: 16.1%) no significant adhesion-reduction was achieved. Except for inflammatory response with Interceed(®), histopathology showed good tissue compatibility of all other devices.

CONCLUSION

4DryField(®) PH and Seprafilm(®) showed significant adhesion prevention capabilities. 4DryField(®) PH achieved the highest adhesion prevention effectiveness without restrictions concerning mode of application and compatibility and, thus, is a promising strategy to prevent abdominal adhesions.

Evaluation of 4DryField® PH as Adhesion Prevention Barrier Tested in an Optimized Adhesion Model in Rats

BACKGROUND

Adhesions due to pelvic/abdominal surgery are a common serious pathology possibly entailing severe complications. This study investigates the adhesion prevention capability of the novel starch-based agent 4DryField® PH, which together with saline solution forms a barrier gel. Herein, an optimized adhesion model (OPAM) inducing severe adhesions/agglutinations with high reproducibility was used.

METHODS

In 19 Lewis rats, a 1 × 2 cm abdominal wall defect was created, the peritoneum of the neighboring cecum was abraded, and both injured areas were approximated by suture. Rats were randomized to control (n = 10) or 4DryField PH treatment (n = 9) groups. Another 8 rats had sham surgery for safety assessment of 4DryField PH. At day 7, the quantity and quality of adhesions were assessed macro-/microscopically and evaluated statistically.

RESULTS

4DryField PH treatment significantly reduced the incidence and severity of adhesions as verified by significantly improved adhesion scorings (0.4 vs. 4.5; 1.1 vs. 9). Histology revealed reconstitution of the cecum and abdominal wall including regeneration of the visceral/parietal peritoneum. In sham-operated rats, 4DryField PH did not induce adhesion formation.

CONCLUSIONS

4DryField PH gel was highly effective in preventing adhesions. Histologically, the injured cecum and abdominal wall regenerated well in the presence of 4DryField PH. Considering the severity of OPAM trauma, the potential of 4DryField PH to prevent adhesions can be rated excellent.

Does long intestinal tube splinting aggravate intestinal adhesions?

OBJECTIVE

Long intestinal tube splinting (LITS) is useful for clinically reducing the recurrence of adhesive small bowel obstruction (ASBO). However, a controversy exists whether LITS aggravates intestinal adhesions. This study evaluated the postoperative effects of LITS relative to simple enterolysis on intestinal adhesions in an experimental porcine model.

METHODS

A porcine model (n = 24) of dense intestinal adhesion was established by abrading the ileal wall with sterile P240 sandpaper. Enterolysis was performed on postoperative day 14. Animals were randomly divided into a group that underwent enterolysis only (control; n = 12) and those who underwent LITS as well as enterolysis (LITS; n = 12). The long intestinal tube was removed on post-LITS day 14, after abdominal radiography. All animals were euthanized on postenterolysis day 28 for assessment of intestinal adhesions using a semiquantitative macroscopic grading scale, hematoxylin-eosin histology, and hydroxyproline assay.

RESULTS

Prior to enterolysis, the experimentally induced intestinal adhesions of the two groups were similar in extent and severity. On postenterolysis day 28 the LITS and control groups were comparable with regard to adhesion loop length (p = .440), macroscopic adhesion severity (p = .820), serosal fibrosis grading (p = .450), and hydroxyproline content of the adhesion ileal segment (p = .630).

CONCLUSION

Placement of the long intestinal tube did not aggravate intestinal adhesions over that of simple enterolysis in this intestinal adhesion porcine model.

Antiadhesive effect and safety of sodium hyaluronate-carboxymethyl cellulose membrane in thyroid surgery

Purpose

A number of researchers have suggested the use of sodium hyaluronate carboxymethyl cellulose (HA-CMC) membrane for preventing postoperative adhesion. This study evaluated the antiadhesive effect and safety of HA-CMC membrane in thyroidectomy for papillary thyroid cancer.

Methods

One hundred sixty-two patients who underwent thyroidectomy were prospectively randomized. In the study group of 80 patients, the 7.5 cm × 13 cm HA-CMC membrane was applied to the operative field after thyroidectomy. The subjects were asked about complications including adhesive symptoms using an 8-item questionnaire at 2 weeks, 3 months, and 6 months after surgery. In addition, items on the appearance of neck wrinkles and scars were evaluated by a physician who had no information about the patient's allocation.

Results

There were no significant differences in complications such as swallowing difficulty, and wrinkles between study and control groups. Both groups presented significantly decreased scores over time in swallowing difficulty, and wrinkles. There were no complications regarding the HA-CMC membrane.

Conclusion

The antiadhesive effect of HA-CMC membrane in thyroid surgery is still uncertain, although it is biologically safe. Further investigation is needed to confirm the antiadhesive effect of HA-CMC membrane in thyroid surgery.

Prevention of pleural adhesions by bioactive polypeptides - a pilot study

OBJECTIVE

Postoperative pleural adhesions lead to major problems in repeated thoracic surgery. To date, no antiadhesive product has been proven clinically effective. Previous studies of differently charged polypeptides, poly-L-lysine (PL) and poly-L-glutamate (PG) have shown promising results reducing postoperative abdominal adhesions in experimental settings. This pilot study examined the possible pleural adhesion prevention by using the PL+PG concept after pleural surgery and its possible effect on key parameters; plasmin activator inhibitor-1 (PAI-1) and tissue growth factor beta 1 (TGFb) in the fibrinolytic process.

METHODS

A total of 22 male rats were used in the study, one control group (n=10) and one experimental group (n=12). All animals underwent primary pleural surgery, the controls receiving saline in the pleural cavity and the experimental group the PL+PG solution administered by spray. The animals were evaluated on day 7. Macroscopic appearance of adhesions was evaluated by a scoring system. Histology slides of the adhesions and pleural biopsies for evaluation of PAI-1 and TGFb1 were taken on day 7.

RESULTS

A significant reduction of adhesions in the PL+PG group (p<0.05) was noted at day 7 both regarding the length and severity of adhesions. There were no significant differences in the concentration of PAI-1 and TGFb1 when comparing the two groups.

CONCLUSIONS

PL+PG may be used to prevent pleural adhesions. The process of fibrinolysis, and fibrosis was though not affected after PLPG administration.

Animal models of intestinal fibrosis: new tools for the understanding of pathogenesis and therapy of human disease

Fibrosis is a serious condition complicating chronic inflammatory processes affecting the intestinal tract. Advances in this field that rely on human studies have been slow and seriously restricted by practical and logistic reasons. As a consequence, well-characterized animal models of intestinal fibrosis have emerged as logical and essential systems to better define and understand the pathophysiology of fibrosis. In point of fact, animal models allow the execution of mechanistic studies as well as the implementation of clinical trials with novel, pathophysiology-based therapeutic approaches. This review provides an overview of the currently available animal models of intestinal fibrosis, taking into consideration the methods of induction, key characteristics of each model, and underlying mechanisms. Currently available models will be classified into seven categories: spontaneous, gene-targeted, chemical-, immune-, bacteria-, and radiation-induced as well as postoperative fibrosis. Each model will be discussed in regard to its potential to create research opportunities to gain insights into the mechanisms of intestinal fibrosis and stricture formation and assist in the development of effective and specific antifibrotic therapies.