Formation and prevention of postoperative abdominal adhesions

Injectable Double Crosslinked Hydrogel-Polypropylene Composite Mesh for Repairing Full-Thickness Abdominal Wall Defects

Abdominal wall defects are common clinical diseases, and mesh repair is the standard treatment method. The most commonly used polypropylene (PP) mesh in clinical practice has the advantages of good mechanical properties, stable performance, and effective tissue integration effect. However, direct contact between abdominal viscera and PP mesh can lead to severe abdominal adhesions. To prevent this, the development of a hydrogel-PP composite mesh with anti-adhesive properties may be an effective measure. Herein, biofunctional hydrogel loaded with rosmarinic acid is developed by modifying chitosan and Pluronic F127, which possesses suitable physical and chemical properties and commendable in vitro biocompatibility. In the repair of full-thickness abdominal wall defects in rats, hydrogels are injected onto the surface of PP mesh and applied to intraperitoneal repair. The results indicate that the use of hydrogel-PP composite mesh can alleviate abdominal adhesions resulting from traditional PP mesh implantation by decreasing local inflammatory response, reducing oxidative stress, and regulating the fibrinolytic system. Combined with the tissue integration ability of PP mesh, hydrogel-PP composite mesh has great potential for repairing full-thickness abdominal wall defects.

Prevalence and Risk Associated With Bladder Injuries During Caesarean Section in a Secondary Care Hospital

Introduction Bladder injury during caesarean section (CS) is not uncommon. Various factors increase the risk of bladder injury during CS, including prolonged labor with bladder distension, pregnancy with a scarred uterus, suspected intra-abdominal adhesions, distorted local anatomy, cesarean hysterectomy, and an increasing number of previous CS. Vigilant preoperative assessment and surgical precision are essential to mitigate these risks and ensure optimal outcomes for mother and child. Objectives To find out the prevalence and risk factors associated with bladder injuries during caesarean section. Methodology Hospital-based retrospective record review of 3600 pregnant women who had undergone cesarean section during the period January 2015 to December 2023 were included in the study. Data was analyzed using SPSS software, version 22 (trial version) (IBM Corp., Armonk, NY). The Chi-square test and Fisher's exact test were used. Ethical clearance was obtained from the Institutional Ethics Committee at Tata Main Hospital Noamundi (approval number NI/CMO/26/24). Result Bladder injury prevalence was reported to be 1.1%. Bladder injuries were significantly (p<0.0001) more among the CS cases with underlined complications as compared to CS cases without any underlined complications. Repeat CSs were found to have a significantly (p<0.001) higher proportion of bladder injuries compared to primary CS.  Conclusion Bladder injuries during cesarean section are a significant concern. The risk factors identified, such as the number of previous cesarean sections and complications during pregnancy, highlight the importance of careful preoperative assessment and surgical precision to prevent such injuries.

Advanced postoperative tissue antiadhesive membranes enabled with electrospun nanofibers

Tissue adhesion is one of the most common postoperative complications, which is frequently accompanied by inflammation, pain, and even dyskinesia, significantly reducing the quality of life of patients. Thus, to prevent the formation of tissue adhesions, various strategies have been explored. Among these methods, placing anti-adhesion membranes over the injured site to separate the wound from surrounding tissues is a simple and prominently favored method. Recently, electrospun nanofibers have been the most frequently investigated antiadhesive membranes due to their tunable porous structure and high porosities. They not only can act as an essential barrier and functional carrier system but also allow for high permeability and nutrient transport, showing great potential for preventing tissue adhesion. Herein, we provide a short review of the most recent applications of electrospun nanofibrous antiadhesive membranes in tendons, the abdominal cavity, dural sac, pericardium, and meninges. Firstly, each section highlights the most representative examples and they are sorted based on the latest progress of related research. Moreover, the design principles, preparation strategies, overall performances, and existing problems are highlighted and evaluated. Finally, the current challenges and several future ways to develop electrospun nanofibrous antiadhesive membranes are proposed. The systematic discussion and proposed directions can shed light on ideas and guide the reasonable design of electrospun nanofibrous membranes, contributing to the development of exceptional tissue anti-adhesive materials in the foreseeable future.

Investigation of anti-adhesion ability of 8-arm PEGNHS-modified porcine pericardium

In post-adhesion surgery, there is a clinical need for anti-adhesion membranes specifically designed for the liver, given the limited efficacy of current commercial products. To address this demand, we present a membrane suitable for liver surgery applications, fabricated through the modification of decellularized porcine pericardium with 20 KDa hexaglycerol octa (succinimidyloxyglutaryl) polyoxyethylene (8-arm PEGNHS). We also developed an optimized modification procedure to produce a high-performance anti-adhesion barrier. The modified membrane significantly inhibited fibroblast cell adherence while maintaining minimal levels of inflammation. By optimizing the modification ratio, we successfully controlled post-adhesion formation. Notably, the 8-arm PEG-modified pericardium with a molar ratio of 5 exhibited the ability to effectively prevent post-adhesion formation on the liver compared to both the control and Seprafilm®, with a low adhesion score of 0.5 out of 3.0. Histological analysis further confirmed its potential for easy separation. Furthermore, the membrane demonstrated regenerative capabilities, as evidenced by the proliferation of mesothelial cells on its surface, endowing anti-adhesion properties between the abdominal wall and liver. These findings highlight the membrane's potential as a reliable barrier for repeated liver resection procedures that require the removal of the membrane multiple times.

Effect of multi arm-PEG-NHS (polyethylene glycol n-hydroxysuccinimide) branching on cell adhesion to modified decellularized bovine and porcine pericardium

Implanting physical barrier materials to separate wounds from their surroundings is a promising strategy for preventing postoperative adhesions. Herein, we develop a material that switches from an anti-adhesive surface to an adhesive surface, preventing adhesion in the early stage of transplantation and then promoting recellularization. In this study, 2-arm, 4-arm, and 8-arm poly(ethylene glycol) succinimidyl glutarate (2-, 4-, 8-arm PEG-NHS) were used to modify the surface of decellularized porcine and bovine pericardium. The number of free amines on the surface of each material significantly decreased following modification regardless of the reaction molar ratio of NH2 and NHS, the number of PEG molecule branches, and the animal species of the decellularized tissue. The structure and mechanical properties of the pericardium were maintained after modification with PEG molecules. The time taken for the PEG molecules to detach through hydrolysis of the ester bonds differed between the samples, which resulted in different cell repulsion periods. By adjusting the reaction molar ratio, the number of PEG molecule branches, and the animal species of the decellularized pericardium, the duration of cell repulsion can be controlled and is expected to provide an anti-adhesion material for a variety of surgical procedures.

Effects of composition and pH on the degradation of hyaluronate and carboxymethyl cellulose gels and release of nanocrystalline silver

Adhesions are fibrous tissue connections which are a common complication of surgical procedures and may be prevented by protecting tissue surfaces and reducing inflammation. The combination of biodegradable polymers and nanocrystalline silver can be used to create an anti-inflammatory gel to be applied during surgery. In this study, sodium hyaluronate and sodium carboxymethyl cellulose were added in concentrations from 0.25% to 1% w/v to aqueous nanocrystalline silver solutions to create viscous gels. Gels were loaded into dialysis cassettes and placed in PBS for 3 days. pH was adjusted using potassium phosphate monobasic and sodium hydroxide. Release of silver into the PBS was measured at several time points. Polymer degradation was compared by measuring the viscosity of the gels before and after the experiment. Gels lost up to 84% of initial viscosity over 3 days and released between 24% and 41% of the added silver. Gels with higher initial viscosity did not have a greater degree of degradation, as measured by percent viscosity reduction, but still resulted in a higher final viscosity. Silver release was not significantly impacted by pH or composition, but still varied between experimental groups.

A Zwitterionic Hydrogel with Anti-Oxidative and Anti-Inflammatory Properties for the Prevention of Peritoneal Adhesion by Inhibiting Mesothelial-Mesenchymal Transition

Postoperative peritoneal adhesion is a serious clinical complication. Various hydrogel barriers have been developed to prevent peritoneal adhesion. However, it remains a challenge to design a hydrogel with desirable physicochemical properties and bioactivities. In this study, a zwitterionic polysaccharide-based multifunctional hydrogel is developed using epigallocatechin-3-gallate (EGCG) to prevent postoperative abdominal adhesion. This hydrogel is simple to use and has desirable properties, such as excellent injectability, self-healing, and non-swelling properties. The hydrogel also has ultralow fouling capabilities, such as superior bactericidal performance, cell and protein adhesion, and low immunogenicity resistance. Moreover, the hydrogel exhibits good antioxidant activity, which is attributed to the integration of EGCG. Furthermore, the detailed mechanism from in vivo and in vitro experimental studies illustrates that hydrogel compositions can synergistically prevent adhesion formation through multiple pathways, including anti-inflammatory and antioxidant capabilities and inhibition effects on the mesothelial-mesenchymal transition (MMT) process induced by transforming growth factor (TGF-β). In summary, this zwitterionic multifunctional hydrogel has great potential to prevent postoperative adhesion formation in the clinical setting.

An anti-inflammatory chondroitin sulfate-poly(lactic-co-glycolic acid) composite electrospinning membrane for postoperative abdominal adhesion prevention

Postoperative abdominal adhesion is a very common and serious complication, resulting in pain, intestinal obstruction and heavy economic burden. Post-injury inflammation that could activate the coagulation cascade and deposition of fibrin is a major cause of adhesion. Many physical barrier membranes are used to prevent abdominal adhesion, but their efficiency is limited due to the lack of anti-inflammatory activity. Here, an electrospinning membrane composed of poly(lactic-co-glycolic acid) (PLGA) providing support and mechanical strength and chondroitin sulfate (CS) conferring anti-inflammation activity is fabricated for preventing abdominal adhesion after injury. The PLGA/CS membrane shows a highly dense fiber network structure with improved hydrophilicity and good cytocompatibility. Importantly, the PLGA/CS membrane with a mass ratio of CS at 20% provides superior anti-adhesion efficiency over a native PLGA membrane and commercial poly(D, L-lactide) (PDLLA) film in abdominal adhesion trauma rat models. The mechanism is that the PLGA/CS membrane could alleviate the local inflammatory response as indicated by the promoted percentage of anti-inflammatory M2-type macrophages and decreased expression of pro-inflammatory factors, such as IL-1β, TNF-α and IL-6, resulting in the suppression of the coagulation system and the activation of the fibrinolytic system. Furthermore, the deposition of fibrin at the abdominal wall was inhibited, and the damaged abdominal tissue was repaired with the treatment of the PLGA/CS membrane. Collectively, the PLGA/CS electrospinning membrane is a promising drug-/cytokine-free anti-inflammatory barrier for post-surgery abdominal adhesion prevention and a bioactive composite for tissue regeneration.

Update on antiadhesion barriers and therapeutics in gynecological surgery

PURPOSE OF REVIEW

Postoperative adhesions remain a clinical challenge to both patients and providers, as they are associated with significant complications and a high economic burden. This article provides a clinical review of currently available antiadhesive agents and promising new therapies that have advanced past animal studies.

RECENT FINDINGS

Several agents have been investigated on their ability to reduce adhesion formation; however, there is no widely acceptable option. The few available interventions are barrier agents and while low-quality evidence suggests that they may be more effective than no treatment, there is no general agreement on their overall efficacy. There is an abundance of research on new solutions; however, their clinical efficacy is yet to be determined.

SUMMARY

Although a wide range of therapeutics have been investigated, majority are halted in animal models with only a select few being studied in humans and ultimately available in the market. Many agents have shown effectiveness in reducing adhesion formation, however, that has not been translated to improvement in clinically relevant outcomes; hence the need for high-quality large randomized trials.

Prevention strategies of postoperative adhesion in soft tissues by applying biomaterials: Based on the mechanisms of occurrence and development of adhesions

Postoperative adhesion (POA) widely occurs in soft tissues and usually leads to chronic pain, dysfunction of adjacent organs and some acute complications, seriously reducing patients' quality of life and even being life-threatening. Except for adhesiolysis, there are few effective methods to release existing adhesion. However, it requires a second operation and inpatient care and usually triggers recurrent adhesion in a great incidence. Hence, preventing POA formation has been regarded as the most effective clinical strategy. Biomaterials have attracted great attention in preventing POA because they can act as both barriers and drug carriers. Nevertheless, even though much reported research has been demonstrated their efficacy on POA inhibition to a certain extent, thoroughly preventing POA formation is still challenging. Meanwhile, most biomaterials for POA prevention were designed based on limited experiences, not a solid theoretical basis, showing blindness. Hence, we aimed to provide guidance for designing anti-adhesion materials applied in different soft tissues based on the mechanisms of POA occurrence and development. We first classified the postoperative adhesions into four categories according to the different components of diverse adhesion tissues, and named them as "membranous adhesion", "vascular adhesion", "adhesive adhesion" and "scarred adhesion", respectively. Then, the process of the occurrence and development of POA were analyzed, and the main influencing factors in different stages were clarified. Further, we proposed seven strategies for POA prevention by using biomaterials according to these influencing factors. Meanwhile, the relevant practices were summarized according to the corresponding strategies and the future perspectives were analyzed.

Peritoneal lavage with Glycyrrhiza glabra is effective in preventing peritoneal adhesion in a rat model

BACKGROUND

Intraperitoneal adhesion formation is a significant problem following surgeries, resulting in substantial clinical and economic consequences. Glycyrrhiza glabra has several pharmacological properties consisting of anti-inflammatory, anti-microbial, anti-oxidant, anti-cancer, and immunomodulatory activities.

AIM

Therefore, we aimed to investigate the impacts of G. glabra on the development of post-operative abdominal adhesion in a rat model.

METHODS

Male Wistar rats weighing 200-250 g were divided into six groups (n = 8): Group 1: normal group (non-surgical), and the surgical groups including Group 2: control group received the vehicle, Group 3: G. glabra 0.5% w/v, Group 4: G. glabra 1% w/v, Group 5: G. glabra 2% w/v, and Group 6: dexamethasone, 0.4% w/v. The intra-abdominal adhesion was performed utilizing soft sterilized sandpaper on one side of the cecum, and the peritoneum was slightly washed with 2 ml of the extract or vehicle. In addition, macroscopic examination of adhesion scoring and the levels of inflammatory mediators [interferon (IFN)-γ, prostaglandin E₂ (PGE₂)], fibrosis markers [interleukin (IL)-4, transforming growth factor (TGF)-ꞵ], and oxidative factors [malondialdehyde (MDA), nitric oxide metabolites (NO), and reduced glutathione (GSH)] were evaluated. In vitro toxicities were also done on mouse fibroblast L929 and NIH/3T3 cell lines.

RESULTS

We found higher levels of adhesion (P < 0.001), IFN-γ(P < 0.001), PGE₂(P < 0.001), IL-4(P < 0.001), TGF-β(P < 0.001), MDA(P < 0.001), and NO(P < 0.001), and lower levels of GSH(P < 0.001) in the control group. In contrast, G. glabra concentration dependent and dexamethasone alleviated the levels of adhesion (P < 0.05), inflammatory mediators (P < 0.001-0.05), fibrosis (P < 0.001-0.05), and oxidative (P < 0.001-0.05) factors, while propagating the anti-oxidant marker (P < 0.001-0.05) in comparison to the control group. Results also showed that the extract did not significantly reduce cell viability up to 300 µg/ml (P > 0.05).

CONCLUSION

G. glabra could concentration-dependently mitigate peritoneal adhesion formation through its anti-inflammatory, anti-fibrosis, and anti-oxidant properties. However, further clinical investigations are required to approve that G. glabra may be a promising candidate against post-surgical adhesive complications.

A comprehensive review of emodin in fibrosis treatment

Emodin is the main pharmacodynamic components of rhubarb, with significant pharmacological effects and clinical efficacy.Emodin has a variety of therapy effects, such as anti-cancer, anti-fibrosis effects, and is widely used to treat encephalitis, diabetic cataract and organ fibrosis. Several studies have shown that emodin has a good treatment effect on organ fibrosis, but the mechanism is complex. Moreover, the evidence of some studies is conflicting and confusing. This paper reviewed the mechanism, pharmacokinetics and toxicology of emodin in fibrosis treatment, and briefly discussed relevant cutting-edge new formulations to improve the efficacy, the result can provide some reference for future study.

Hybrid argon plasma coagulation (HybridAPC) versus sharp excision for the treatment of endometriosis: a prospective randomized clinical trial

PURPOSE

Endometriosis is a benign, but potentially serious gynaecological condition in terms of abdominal pain and impaired fertility. Laparoscopic excision techniques are considered the therapeutic standard. HybridAPC is presented as a novel technique for the non-contact thermal ablation of peritoneal endometriosis with simultaneous protection of the underlying thermosensitive structures by creating a needle-free elevated fluid cushion which enables a safer exposure and distance, as well as potentially improved peritoneal conditioning prior to APC.

METHODS

In this prospective randomized clinical trial, 39 patients with 132 superficial endometriotic lesions in total were treated with HybridAPC or sharp excision in an initial laparoscopic procedure according to randomization. In a second-look laparoscopy, adhesion formation was rated macroscopically. Histologic samples were taken from previously treated areas for evaluation of eradication rate.

RESULTS

The eradication rate was not significantly different between HybridAPC treatment and sharp excision (65 vs. 81%, p = .55). Adhesions formed in 5% of HybridAPC-treated lesions and in 10% after sharp excision (p = .49). HybridAPC treatment was significantly faster than sharp excision (69 vs. 106 s, p < .05). No intra- and postoperative complications were registered.

CONCLUSION

This clinical trial demonstrates the feasibility of this novel surgical technique with a promising impact on adhesion prevention. Compared to sharp excision, HybridAPC is likely to be a safe, tissue-preserving, and fast method for the treatment of peritoneal endometriosis.

NFK prevent postoperative abdominal adhesion through downregulating the TGF-β1 signaling pathway

BACKGROUND

Postoperative abdominal adhesions (PAAs) represent a frequent condition occurring in more than 90% of patients undergoing abdomen and pelvic surgeries, which can cause chronic abdominal pain, female infertility, and repeated bowel obstruction, requiring repetitive surgical interventions causing morbidity and mortality, as well as high costs. It is therefore of paramount clinical importance and significance to develop practical and reliable strategies for preventing the occurrence of PAAs.

METHODS AND RESULTS

In this study, we demonstrated that Nianfukang (NFK, composed of polyethylene glycol 1450 and diclofenac sodium) is highly effective in preventing PAAs, likely by reducing leukocytes and inflammatory factors in the abdominal cavity, and inhibiting intestinal fibrosis in a rat model of PAAs induced by postoperative cecum scraping. We further uncovered that NFK downregulates the expression of TGF-β1, a key factor for adhesion formation, to suppress the TGF-β1/TGF-βRIII/Smad2 signaling pathway, thereby inhibiting the proliferation and migration of fibroblasts and provided evidences for the involvement of the TGF-β1/TGF-βRIII/Smad2 axis in the prevention of PAAs in normal human colon fibroblast CCD-18Co.

CONCLUSIONS

Our findings support NFK as a potential anti-adhesive product that has the advantages of significant effectiveness, safety profile, and low cost, as well as clear mechanism of action.

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.

Balance of antiperitoneal adhesion, hemostasis, and operability of compressed bilayer ultrapure alginate sponges

In surgery, both antiperitoneal adhesion barriers and hemostats with high efficiency and excellent handling are necessary. However, antiadhesion and hemostasis have been examined separately. In this study, six different ultrapure alginate bilayer sponges with thicknesses of 10, 50, 100, 200, 300, and 500 μm were fabricated via lyophilization and subsequent mechanical compression. Compression significantly enhanced mechanical strength and improved handling. Furthermore, it had a complex effect on dissolution time and contact angle. Therefore, the 100 μm compressed sponge showed the highest hemostatic activity in the liver bleeding model in mice, whereas the 200 μm sponge demonstrated the highest antiadhesion efficacy among the compressed sponges in a Pean crush hepatectomy-induced adhesion model in rats. For the first time, we systematically evaluated the effect of sponge compression on foldability, fluid absorption, mechanical strength, hemostatic effect, and antiadhesion properties. The optimum thickness of an alginate bilayer sponge by compression balances antiperitoneal adhesion and hemostasis simultaneously.

Effects of Oral Zafirlukast, Sildenafil, or Pirfenidone on the Formation of Postsurgical Intra-abdominal Adhesions in an Experimental Rat Model

INTRODUCTION

Intra-abdominal adhesions' main etiology is surgical procedures that commonly require reintervention. Oral treatments with Sildenafil, Zafirlukast, and Pirfenidone have yielded decreased severity of fibrotic phenomena secondary to the introduction of foreign material. This study aimed to evaluate the efficacy of oral Zafirlukast, Sildenafil or Pirfenidone treatment on reducing or preventing intra-abdominal adhesions in an experimental rat model.

METHODS

Four groups, each of 10 male Wistar rats weighing 250-300 g, were used. A midline laparotomy was used to excise an area of 1.5´1.5cm and reconstructed with polypropylene mesh fixed to the abdominal wall. After 12 h, oral doses of Zafirlukast (1.25 mg/kg, group B), Sildenafil (15 mg/kg, group C), or Pirfenidone (500 mg/kg, group D) were given every day for eight days. The control group, A, received no treatment. At day nine, animals were reoperated. The implant was resected after ethically approved euthanasia and specimens were fixed in 10% formaldehyde for histopathology.

RESULTS

Control group A yielded adhesions with greater fibrovascular density and neighboring organ involvement than the other groups (P = 0.001), as well as intense inflammatory infiltrates and numerous granulomas (P = 0.04). Adhesions in group C had less fibrovascular density (P = 0.03) with decreased serosal injuries (P = 0.001) and less organ involvement. Group D had reduced adhesions without organ involvement (P < 0.01), and less inflammatory infiltrates, collagen fibers, and foreign body granulomas than groups B or C (P < 0.01).

CONCLUSIONS

Oral administration of these agents did not prevent adhesions but ameliorated them. Oral Pirfenidone offered the best performance and could be recommended for human use.

Anti-adhesive effect of chondrocyte-derived extracellular matrix surface-modified with poly-L-lysine (PLL)

After an injury, soft tissue structures in the body undergo a natural healing process through specific phases of healing. Adhesions occur as abnormal attachments between tissues and organs through the formation of blood vessels and/or fibrinous adhesions during the regenerative repair process. In this study, we developed an adhesion-preventing membrane with an improved physical protection function by modifying the surface of chondrocyte-derived extracellular matrices (CECM) with anti-adhesion function. We attempted to change the negative charge of the CECM surface to neutral using poly-L-lysine (PLL) and investigated whether it blocked fibroblast adhesion to it and showed an improved anti-adhesion effect in animal models of tissue adhesion. The surface of the membrane was modified with PLL coating (PLL 10), which neutralized the surface charge. We confirmed that the surface characteristics except for the potential difference were maintained after the modification and tested cell attachment in vitro. Adhesion inhibition was identified in a peritoneal adhesion animal model at 1 week and in a subcutaneous adhesion model for 4 weeks. N-CECM suppressed fibroblast and endothelial cell adhesion in vitro and inhibited abdominal adhesions in vivo. The CECM appeared to actively inhibit the infiltration of endothelial cells into the injured site, thereby suppressing adhesion formation, which differed from conventional adhesion barriers in the mode of action. Furthermore, the N-CECM remained intact without degradation for more than four weeks in vivo and exerted anti-adhesion effects for a long time. This study demonstrated that PLL10 surface modification rendered a neutral charge to the polymer on the extracellular matrix surface, thereby inhibiting cell and tissue adhesion. Furthermore, this study suggests a means to modify extracellular matrix surfaces to meet the specific requirements of the target tissue in preventing post-surgical adhesions. This article is protected by copyright. All rights reserved.

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-surgical adhesion bands by local administration of frankincense n-hexane extract

Background

and purpose: The formation of postoperative intra-abdominal adhesion band formation may lead to severe complications. This study aimed to evaluate the preventive effect of local administration of frankincense n-hexane extract (FHE) on the formation of postsurgical adhesion bands.

Materials and methods

FHE was extracted from the resin of a Boswellia sacra tree and its components were identified by gas chromatography-mass spectrometry (GC-MS). In an animal model, the expression levels of TNF-α and TGF-β1 cytokines after application of FHE were assessed to check the inflammatory and fibrotic cues, respectively.

Results

Following FHE compound analysis, in vivo experiments demonstrated that intraoperative local administration of FHE resulted in the prevention of adhesion band formation. The adhesion grades in the FHE-treated group were significantly lower than those in the negative control (NC) and the positive control (Interceed). The infiltration of inflammatory cells observed by histopathology revealed a significant anti-inflammatory potential of FHE. Furthermore, the gene expression results proved that significant suppression of TNF-α and TGF-β1 was responsible for its antiadhesion properties.

Conclusions

The study reported the potential of FHE as an ointment for the prevention of adhesion bands.

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Recognition of compounds with anti-inflammatory, antifibrotic activities in FHE using gas chromatography-mass spectrometry.

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The avoidance of adhesion bands formation, in vivo following intraoperative local administration of FHE.

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A notable anti-inflammatory potential of FHE detected by histopathology results.

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Approving the regulation of TNF-α and TGF-β1 involved in the intra-abdomen adhesion preventive properties of FHE.

Postoperative morbidity and quality of life between totally laparoscopic total gastrectomy and laparoscopy-assisted total gastrectomy: a propensity-score matched analysis

BACKGROUND

This study aimed to evaluate the surgical outcome and quality of life (QoL) of totally laparoscopic total gastrectomy (TLTG) compared with laparoscopy-assisted total gastrectomy (LATG) in patients with clinical stage I gastric cancer.

METHODS

From 2012 to 2018, EGC patients who underwent TLTG (n = 223), including the first case with intracorporeal hemi-double stapling, were matched to those who underwent LATG (n = 114) with extracorporeal circular stapling, using 2:1 propensity score matching (PSM). Prospectively collected morbidity was compared between the TLTG and LATG groups in conjunction with the learning curve. The European Organization for Research and Treatment of Cancer (EORTC) QoL questionnaires QLQ-C30, STO22, and OG25 were prospectively surveyed during postoperative 1 year for patient subgroups.

RESULTS

After PSM, grade I pulmonary complication rate was lower in the TLTG group (n = 213) than in the LATG group (n = 111) (0.5% vs. 5.4%, P = 0.007). Other complications were not different between the groups. The learning curve of TLTG was overcome at the 26th case in terms of the comprehensive complication index. The TLTG group after learning curve showed lower grade I pulmonary complication rate than the matched LATG group (0.5% vs. 4.7%, P = 0.024). Regarding postoperative QoL, the TLTG group (n = 63) revealed less dysphagia (P = 0.028), pain (P = 0.028), eating restriction (P = 0.006), eating (P = 0.004), odynophagia (P = 0.023) than the LATG group (n = 21). Multivariate analyses for each QoL item demonstrated that TLTG was the only common independent factor for better QoL.

CONCLUSIONS

TLTG reduced grade I pulmonary complications and provided better QoL in dysphagia, pain, eating, odynophagia than LATG for patients with clinical stage I gastric cancer.

Physically Cross-Linked Hyaluronan-Based Ultrasoft Cryogel Prepared by Freeze-Thaw Technique as a Barrier for Prevention of Postoperative Adhesions

Postsurgical peritoneal adhesions are a common and serious postoperative complication after various peritoneal surgeries, such as pelvic and abdominal surgery. Various studies have shown that peritoneal adhesions can be minimized or prevented by physical anti-adhesion barriers, including membranes, knits, and hydrogels. Hydrogels have attracted great attention in preventing peritoneal adhesions because the dimensional architecture of hydrogels is similar to that of the native extracellular matrix. However, chemical cross-linkers had to be used in the preparation of chemical hydrogels, which may have problems in cytotoxicity or unwanted side effects. This fact prompts us to create alternative cross-linking methods for the development of biocompatible hydrogels as physical barriers. Herein, we report a physically cross-linked flexible hyaluronan (HA) cryogel prepared via a freeze-thaw technique as a novel anti-adhesion biomaterial for completely preventing postsurgical peritoneal adhesions. In vitro studies demonstrated that this physically cross-linked HA cryogel exhibited excellent biocompatibility, the inherently desirable biocompatibility and functionality of HA being integrally retained as much as possible. Intriguingly, the rheological properties and appropriate biodegradability of the cryogels were readily tailored and tunable by way of the gelation process. In vivo assessments suggested that the cryogel, as a physical barrier, satisfactorily prevented fibroblast penetration and attachment between the injured tissues and nearby normal organs. Furthermore, the molecular mechanism studies revealed that the HA cryogel could prevent peritoneal adhesion by inhibiting inflammatory response and modulation of the fibrinolytic system. Our results show that HA ultrasoft cryogel is a promising clinical candidate for prolonged adhesion prevention.

Post-Operative Adhesions: A Comprehensive Review of Mechanisms

Post-surgical adhesions are common in almost all surgical areas and are associated with significant rates of morbidity, mortality, and increased healthcare costs, especially when a patient requires repeat operative interventions. Many groups have studied the mechanisms driving post-surgical adhesion formation. Despite continued advancements, we are yet to identify a prevailing mechanism. It is highly likely that post-operative adhesions have a multifactorial etiology. This complex pathophysiology, coupled with our incomplete understanding of the underlying pathways, has resulted in therapeutic options that have failed to demonstrate safety and efficacy on a consistent basis. The translation of findings from basic and preclinical research into robust clinical trials has also remained elusive. Herein, we present and contextualize the latest findings surrounding mechanisms that have been implicated in post-surgical adhesion formation.

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.

Injectable Self-Healing Hydrogel via Biological Environment-Adaptive Supramolecular Assembly for Gastric Perforation Healing

Developing effective internal wound dressing materials is important for postoperative tissue regeneration while remains a challenge due to the poor biological environment-adaptability of conventional materials. Here, we report an example of injectable self-healing hydrogel based on gastric environment-adaptive supramolecular assembly, and have explored its application for gastric perforation healing. By leveraging the gastric environment-modulated supramolecular interactions, the self-assembled hydrogel network is orchestrated with sensitive thermo-responsibility, injectability, printability and rapid self-healing capability. The hydrogel dressing can effectively inhibit the attachment of microorganisms and demonstrates outstanding antibiofouling property. In vivo rat model further demonstrates the as-prepared hydrogel dressing simplifies the surgical procedures, reduces postoperative complications as well as enhances the healing process of gastric perforation compared with the conventional treatment. This work provides useful insights into the development of biological environment-adaptive functional materials for various biomedical applications.

A nano chitosan membrane barrier prepared via Nanospider technology with non-toxic solvent for peritoneal adhesions' prevention

Peritoneal adhesion is one of the most common postsurgical complications and can cause bowel obstruction, pelvic pain, and infertility. Setting up a physical barrier directly between the injured site and surrounding tissues is an effective solution for preventing this adverse situation. This study investigated a chitosan electrospun membrane (CSEM) as a potent anti-adhesion barrier, which was prepared by a needleless technology called Nanospider. Scanning electron microscopy revealed that CSEM is a laminated nanofiber with good mechanical properties. The fiber is uniform with the diameter distributing in the range of 100-120 nm. The tensile strength can reach 27.45 ± 6.30 MPa with a maximum elongation at break of 18.50 ± 1.44%, which makes it stick easily to damaged parts but not to be easily damaged by tissue friction. The growth of S. aureus on CSEM was 59.18% lower than the control at 10 h, which indicates its better antibacterial property. In addition, CSEM has good coagulant and biocompatibility characteristics. It can perform hemostatic function within 10 min and the L929 mouse fibroblast viability on it was 92.18% ± 1.08% on the seventh day. In vivo experiments indicated that CSEM significantly prevented peritoneal adhesions within four weeks after surgery with wound surface coverage. These results indicate that CSEM is a promising anti-adhesion barrier material.

Antibacterial, hemostasis, adhesive, self-healing polysaccharides-based composite hydrogel wound dressing for the prevention and treatment of postoperative adhesion

Herein, we fabricated novel self-healing, in situ injectable, biodegradable, and non-toxic hydrogels anti-adhesion barrier materials composed of N, O-carboxymethyl chitosan (N,O-CS) and oxidized dextran (ODA) without requiring any chemical cross-linking agent or external stimuli triggers for the prevention and treatment of post-operative peritoneal adhesions. The N,O-CS/ODA hydrogels have a good suitable gelation time, good cytocompatibility and hemocompatibility, good antibacterial activity, excellent biodegradable and biocompatible, and can effectively inhibit the adhesion of fibroblasts to the wound, thereby suggesting that N,O-CS/ODA hydrogels are suitable for preventing post-operative adhesion. Meanwhile, a rat injury sidewall-cecum abrasion model is developed to investigate the efficacy of these hydrogels in achieving post-operative anti-adhesion. A significant reduction of peritoneal adhesions (10% rat with lower score adhesion) is observed in the N,O-CS/ODA-hydrogel-treated group compared with the commercial hydrogel and control groups. These results demonstrated that N,O-CS/ODA hydrogel could effectively prevent post-operative peritoneal adhesion without side effects. Therefore, the N,O-CS/ODA hydrogels with multi-functional properties exhibit great potential for the prevention and treatment of postoperative adhesion.

An Ultrasoft Self-Fused Supramolecular Polymer Hydrogel for Completely Preventing Postoperative Tissue Adhesion

The intermolecular H-bonding density heavily influences the gelation and rheological behavior of hydrogen-bonded supramolecular polymer hydrogels, thus offering a delicate pathway to tailor their physicochemical properties for meeting a specific biomedical application. Herein, one methylene spacer between two amides in the side chain of N-acryloyl glycinamide (NAGA) is introduced to generate a variant monomer, N-acryloyl alaninamide (NAAA). Polymerization of NAAA in aqueous solution affords an unprecedented ultrasoft and highly swollen supramolecular polymer hydrogel due to weakened H-bonds caused by an extra methylene spacer, which is verified by variable-temperature Fourier transform infrared (FTIR) spectroscopy and simulation calculation. Intriguingly, poly(N-acryloyl alaninamide) (PNAAA) hydrogel can be tuned to form a transient network with a self-fused and excellent antifouling capability that results from the weakened dual amide H-bonding interactions and enhanced water-amide H-bonding interactions. This self-fused PNAAA hydrogel can completely inhibit postoperative abdominal adhesion and recurrent adhesion after adhesiolysis in vivo. This transient hydrogel network allows for its disintegration and excretion from the body. The molecular mechanism studies reveal the signal pathway of PNAAA hydrogel in inhibiting inflammatory response and regulating fibrinolytic system balance. This self-fused, antifouling ultrasoft supramolecular hydrogel is promising as a barrier biomaterial for completely preventing postoperative tissue adhesion.

Biodegradable Zwitterionic Cream Gel for Effective Prevention of Postoperative Adhesion

Postoperative peritoneal adhesions were frequent complications for almost any types of abdominal and pelvic surgery. This led to numerous medical problems and huge financial burden to the patients. Current anti-adhesion strategies focused mostly on physical barriers including films and hydrogels. However, they can only alleviate or reduce adhesions to certain level and their applying processes were far from ideal. This work reported the development of a biodegradable zwitterionic cream gel presenting a series of characters for an idea anti-adhesion material, including unique injectable yet malleable and self-supporting properties, which enabled an instant topical application, no curing, waiting or suturing, no hemostasis requirement, protein/cell resistance and biodegradability. The cream gel showed a major advancement in anti-adhesion efficacy by completely and reliably preventing a primary and a more severe recurrent adhesion in rat models.

Advancement of Biomaterial-Based Postoperative Adhesion Barriers

Postoperative peritoneal adhesion (PPA) is a prevalent incidence that generally happens during the healing process of traumatized tissues. It causes multiple severe complications such as intestinal obstruction, chronic abdominal pain, and female infertility. To prevent PPA, several antiadhesion materials and drug delivery systems composed of biomaterials are used clinically, and clinical antiadhesive is one of the important applications nowadays. In addition to several commercially available materials, like film, spray, injectable hydrogel, powder, or solution type have been energetically studied based on natural and synthetic biomaterials such as alginate, hyaluronan, cellulose, starch, chondroitin sulfate, polyethylene glycol, polylactic acid, etc. Moreover, many kinds of animal adhesion models, such as cecum abrasion models and unitary horn models, are developed to evaluate new materials' efficacy. A new animal adhesion model based on hepatectomy and conventional animal adhesion models is recently developed and a new adhesion barrier by this new model is also developed. In summary, many kinds of materials and animal models are studied; thus, it is quite important to overview this field's current progress. Here, PPA is reviewed in terms of the species of biomaterials and animal models and several problems to be solved to develop better antiadhesion materials in the future are discussed.

Fouling-resistant zwitterionic polymers for complete prevention of postoperative adhesion

Postoperative adhesions are most common issues for almost any types of abdominal and pelvic surgery, leading to adverse consequences. Pharmacological treatments and physical barrier devices are two main approaches to address postoperative adhesions but can only alleviate or reduce adhesions to some extent. There is an urgent need for a reliable approach to completely prevent postoperative adhesions and to significantly improve the clinical outcomes, which, however, is unmet with current technologies. Here we report that by applying a viscous, cream-like yet injectable zwitterionic polymer solution to the traumatized surface, postoperative adhesion was completely and reliably prevented in three clinically relevant but increasingly challenging models in rats. The success rate of full prevention is over 93% among 42 animals tested, which is a major leap in antiadhesion performance. Clinically used Interceed film can hardly prevent the adhesion in any of these models. Unlike current antiadhesion materials serving solely as physical barriers, the "nonfouling" zwitterionic polymer functioned as a protective layer for antiadhesion applications with the inherent benefit of resisting protein/cell adhesions. The nonfouling nature of the polymer prevented the absorption of fibronectins and fibroblasts, which contribute to the initial and late-stage development of the adhesion, respectively. This is the key working mechanism that differentiated our "complete prevention" approach from current underperforming antiadhesion materials. This work implies a safe, effective, and convenient way to fully prevent postoperative adhesions suffered by current surgical patients.

The usefulness of re-attachability of anti-adhesive cross-linked gelatin film and the required physical and biological properties

BACKGROUND

To overcome the unfavorable issues associated with conventional anti-adhesive HA/CMC film, we developed an anti-adhesive thermally cross-linked gelatin film.

OBJECTIVE

We tried to clarify the re-attachability of the film and the required properties concerning the film thickness, stiffness and anti-adhesion effect.

METHODS

To determine the optimal thickness, 5 kinds of the thickness of gelatin film and the conventional film were analyzed by the tensile test, shearing test, buckling test and tissue injury test. Finally, using the optimal film thickness, we tried to clarify the anti-adhesion effect of the reattached film.

RESULTS

The tensile and shearing test showed gelatin films ≥30 μm thick had greater tensile strength and a smaller number of film fractures, than the conventional film. The buckling and tissue injury test showed gelatin films ≥60 μm thick had higher buckling strength and worse injury scores than the conventional film. The anti-adhesive effect of re-attached gelatin film using optimal thickness (30-40 μm) found the anti-adhesion score was significantly better than that of the control.

CONCLUSIONS

Provided it has an optimal thickness, gelatin film can be reattached with enough physical strength not to tear, safety stiffness not to induce tissue injury, and a sufficient anti-adhesion effect.

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.

Postoperative peritoneal adhesion: an update on physiopathology and novel traditional herbal and modern medical therapeutics

Postoperative peritoneal adhesion (PPA) is a serious clinical condition that affects the high percentage of patients after abdominal surgery. In this review, we have tried to focus on pathophysiology and different underlying signal pathways of adhesion formation based on recent progress in the molecular and cellular mechanisms. Also, the strategies, developed based on traditional herbal and modern medicines, to prevent and treat the PPA via regulation of the molecular mechanisms were investigated. The search engines such as Google Scholar, PubMed, Scopus, and Science Direct have been used to evaluate the current literature related to the pathogenesis of adhesion formation and novel products. Recently, different mechanisms have been defined for adhesion formation, mainly categorized in fibrin formation and adhesion fibroblast function, inflammation, and angiogenesis. Therefore, the suppression of these mechanisms via traditional and modern medicine has been suggested in several studies. While different strategies with encouraging findings have been developed, most of the studies showed contradictory results and were performed on animals. The herbal products have been introduced as safe and effective agent which can be considered in future preclinical and clinical studies. Although a wide range of therapeutics based on traditional and modern medicines have been suggested, there is no agreement in the efficacy of these methods to prevent or treat adhesion formation after surgeries. Further basic and clinical researches are still needed to propose the efficiency of recommended strategies for prevention and treatment of PPA.

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.

Zwitterionic amino acid-based Poly(ester urea)s suppress adhesion formation in a rat intra-abdominal cecal abrasion model

Hernia repair outcomes have improved with more robust material options for surgeons and optimized surgical techniques. However, ventral hernia repairs remain challenging with an inherent risk of post-surgical adhesions in the peritoneal space which can occur regardless of interventional material or its surgical placement. Herein, amino acid-based poly(ester urea)s (PEUs) with varied amount of an allyl ether side chains were modified post polymerization modification with the zwitterionic sulfnate group (3-((3-((3-mercaptopropanoyl)oxy)propyl) dimethylammonio)propane-1-sulfonate) to promote anti-adhesive properties. These alloc-PEUs were processed using roll-to-roll fabrication methods to afford films that were amenable to surface functionalization via a zwitterion-thiol. Functional group availability on the surface was confirmed via fluorescence microscopy, x-ray photoelectron spectroscopy (XPS), and quartz crystal microbalance (QCM) measurements. Zwitterionic treated PEUs exhibited reduced fibrinogen adsorption in vitro when compared to unfunctionalized control polymer. A rat intrabdominal cecal abrasion adhesion model was used to assess the extent and tenacity of adhesion formation in the presence of the PEUs. The 10% alloc-PEU zwitterion functionalized material was found to reduce the extent and tenacity of adhesions when compared to adhesion controls and the unfunctionalized PEU controls.

Comparison of Honey versus Polylactide Anti-Adhesion Barrier on Peritoneal Adhesion and Healing of Colon Anastomosis in Rabbits

BACKGROUND:

Postoperative adhesion is still a consequence of intra-abdominal surgeries, which results in bowel obstruction and abdominopelvic pain. Bowel anastomosis as a common abdominal surgery has the incidence of leakage in up to 30% of patients that increase morbidity and mortality. Due to similar pathways of adhesion formation and wound healing, it is important to find a way to reduce adhesions and anastomosis leakage.

AIM:

This study was designed to compare antiadhesive as well as anastomosis healing improvement effect of honey and polylactide anti-adhesive barrier film.

METHODS:

Forty-five rabbits divided into three groups of honey, adhesion barrier film, and control group in an animal study. Under a similar condition, rabbits underwent resection and anastomosis of cecum under general anaesthesia. In the first group, honey was used at the anastomosis site, in the second one polylactide adhesion barrier film utilised, and the third one was the control group. Adhesion, as well as anastomosis leakage, was assessed after 21 days. Data were analysed using the Statistical Package for Social Scientists (SPSS) for Windows version 25.

RESULTS:

Three groups of 15 rabbits were studied. The results showed that mean peritoneal adhesion score (PAS) was lower in the honey group (1.67) in comparison to the adhesion barrier film group (3.40) and the control group (6.33).

CONCLUSION:

Bio-absorbable polylactide barrier has an anti-adhesion effect but is not suitable for intestinal anastomosis in rabbits. Further studies needed to evaluate these effects on human beings.

Chinese Trauma Surgeon Association for management guidelines of vacuum sealing drainage application in abdominal surgeries-Update and systematic review

Vacuum sealing drainage (VSD) is frequently used in abdominal surgeries. However, relevant guidelines are rare. Chinese Trauma Surgeon Association organized a committee composed of 28 experts across China in July 2017, aiming to provide an evidence-based recommendation for the application of VSD in abdominal surgeries. Eleven questions regarding the use of VSD in abdominal surgeries were addressed: (1) which type of materials should be respectively chosen for the intraperitoneal cavity, retroperitoneal cavity and superficial incisions? (2) Can VSD be preventively used for a high-risk abdominal incision with primary suture? (3) Can VSD be used in severely contaminated/infected abdominal surgical sites? (4) Can VSD be used for temporary abdominal cavity closure under some special conditions such as severe abdominal trauma, infection, liver transplantation and intra-abdominal volume increment in abdominal compartment syndrome? (5) Can VSD be used in abdominal organ inflammation, injury, or postoperative drainage? (6) Can VSD be used in the treatment of intestinal fistula and pancreatic fistula? (7) Can VSD be used in the treatment of intra-abdominal and extra-peritoneal abscess? (8) Can VSD be used in the treatment of abdominal wall wounds, wound cavity, and defects? (9) Does VSD increase the risk of bleeding? (10) Does VSD increase the risk of intestinal wall injury? (11) Does VSD increase the risk of peritoneal adhesion? Focusing on these questions, evidence-based recommendations were given accordingly. VSD was strongly recommended regarding the questions 2-4. Weak recommendations were made regarding questions 1 and 5-11. Proper use of VSD in abdominal surgeries can lower the risk of infection in abdominal incisions with primary suture, treat severely contaminated/infected surgical sites and facilitate temporary abdominal cavity closure.

PLGA/PLCA casting and PLGA/PDPA electrospinning bilayer film for prevention of postoperative adhesion

Postoperative adhesion is a common complication and preventing adhesions during or immediately after operation is particularly important. The application of solid barrier materials represents the most successful clinical strategy to prevent postoperative adhesion. However, a simple physical barrier effect might be insufficient in preventing adhesion satisfactorily. Multilayered structures can be designed with an outer layer as the barrier and an inner layer to respond to relative drug release. In this article, bilayer film composed of a PLGA/PLCA casting layer as barrier and PLGA/PDPA electrospinning layer to respond to the release of anti-fibrosis drug l-Phe was designed and synthesized. The adhesion prevention effect of the above PLGA/PLCA/PDPA bilayer film was examined and compared with single PLGA/PLCA casting film and single PLGA/PDPA electrospinning film by applying rabbit sidewall defect-cecum abrasion model. As demonstrated by histological observation and immunohistochemical analysis, the bilayer film was the most effective of the three films in postoperative adhesion prevention in terms of both physical barrier effect and anti-fibrosis effect of the PDPA macromolecular prodrug. Besides anti-fibrosis effect, PDPA could also suppress excess proliferation of vascular endothelial cells and microvessel caused by long-term stimulation of implantation materials to the surrounding tissues. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2030-2039, 2019.

Cross-linked electrospun cartilage acellular matrix/poly(caprolactone-co-lactide-co-glycolide) nanofiber as an antiadhesive barrier

In this work, we chose cartilage acellular matrix (CAM) as a promising antiadhesive material because CAM effectively inhibits the formation of blood vessels, and we used electrospinning to prepare antiadhesive barriers. Additionally, we synthesized N-hydroxysuccinimide (NHS)-poly(caprolactone-co-lactide-co-glycolide)-NHS (MP) copolymers (to tune degradation) as a cross-linking agent for CAM. This is the first report on the development of electrospun cross-linked (Cx) CAM/MP (CA/P) nanofiber (NF) (Cx-CA/P-NF) with a tunable degradation period as an antiadhesive barrier. Compared with the CA/P-NF before cross-linking, the electrospun Cx-CA/P-NF after cross-linking showed different biodegradation. Cx-CA/P-NF significantly inhibited the in vitro attachment and proliferation of human umbilical vein endothelial cells (HUVECs), as confirmed by an MTT assay and scanning electron microscopy images. Cx-CA/P-NFs implanted between a surgically damaged peritoneal wall and cecum gradually degraded in 7 days; this process was monitored by NIR imaging. The in vivo evaluation of the anti-tissue adhesive effect of Cx-CA/P-NFs revealed little adhesion, few blood vessels, and negligible inflammation at 7 days determined by hematoxylin and eosin staining. ED1 staining of Cx-CA/P-NFs showed infiltration of few macrophages because of the inflammatory response to the Cx-CA/P-NF as compared with an untreated injury model. Additionally, Cx-CA/P-NFs significantly suppressed the formation of blood vessels between the peritoneal wall and cecum, according to CD31 staining. Overall, Cx-CA/P-NFs yielded little adhesion, infiltration by macrophages, or formation of blood vessels in a postoperative antiadhesion assay. Thus, it is reasonable to conclude that the Cx-CA/P-NF designed herein successfully works as an antiadhesive barrier with a tunable degradation period.

STATEMENT OF SIGNIFICANCE

The cartilage acellular matrix (CAM) can inhibit the formation of fibrous tissue bridges and blood vessels between the tissue at an injured site and the surrounding healthy tissues. However, CAM has not been rigorously investigated as an antiadhesive barrier. In this manuscript, the cross-linked CAM nanofiber (Cx-CA/P-NF) designed herein successfully works as an antiadhesive barrier. Cx-CA/P-NFs yielded little adhesion, infiltration by macrophages, or formation of blood vessels in a postoperative antiadhesion assay. Moreover, we demonstrated the suitable properties of Cx-CA/P-NF such as easy cross-linking by maintaining the antiadhesive properties, controllable biodegradation, and in vivo antiadhesive effect of Cx-CA/P-NF.

The in vivo anti-fibrotic function of calcium sensitive receptor (CaSR) modulating poly(p-dioxanone-co-l-phenylalanine) prodrug

In present study, the apoptosis induction and proliferation suppression effects of l-phenylalanine (l-Phe) on fibroblasts were confirmed. The action sites of l-Phe on fibroblasts suppression were deduced to be calcium sensitive receptor (CaSR) which could cause the release of endoplasmic reticulum (ER) Ca²⁺ stores; disruption of intracellular Ca²⁺ homeostasis triggers cell apoptosis via the ER or mitochondrial pathways. The down-regulation of CaSR were observed after the application of l-Phe, and the results those l-Phe triggered the increasing of intracellular Ca²⁺ concentration and calcineurin expression, and then the apoptosis and increasing G1 fraction of fibroblasts have verified our deduction. Hence, l-Phe could be seen as a kind of anti-fibrotic drugs for the crucial participation of fibroblast in the occurrence of fibrosis. And then, poly(p-dioxanone-co-l-phenylalanine) (PDPA) which could prolong the in-vivo anti-fibrotic effect of l-Phe for the sustained release of l-Phe during its degradation could be treated as anti-fibrotic polymer prodrugs. Based on the above, the in vivo anti-fibrotic function of PDPA was evaluated in rabbit ear scarring, rat peritoneum lipopolysaccharide, and rat sidewall defect/cecum abrasion models. PDPA reduced skin scarring and suppressed peritoneal fibrosis and post operation adhesion as well as secretion of transforming growth factor-β1 in injured tissue. These results indicate that PDPA is an effective agent for preventing fibrosis following tissue injury.

STATEMENT OF SIGNIFICANCE

We have previously demonstrated that poly(p-dioxanone-co-l-phenylalanine) (PDPA) could induce apoptosis to fibroblast and deduced that the inhibitory effect comes from l-phenylalanine. In present study, the inhibition mechanism of l-phenylalanine on fibroblast proliferation was demonstrated. The calcium sensitive receptor (CaSR) was found to be the action site. The CaSR was downregulated after the application of l-phenylalanine, and then the ER Ca²⁺ stores were released. The released Ca²⁺ can simultaneously activate Ca²⁺/calcineurin and then trigger apoptosis and G1 arrest of fibroblast. Hence, l-phenylalanine could be seen as anti-fibrosis drug and PDPA which conjugate l-phenylalanine by hydrolytic covalent bonds could be seen as l-phenylalanine polymer prodrug. Based above, the in vivo anti-fibrotic function of PDPA were verified in three different animal models.