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

A novel strategy for addressing post-surgical abdominal adhesions: Janus hydrogel

Abdominal adhesions are a frequent complication after abdominal surgery, which can cause significant pain and burden to patients. Despite various treatment options, including surgical intervention and pharmacotherapy, these often fail to consistently and effectively prevent postoperative abdominal adhesions. Janus hydrogel is famous for its asymmetric characteristics, which shows great prospects in the prevention and treatment of abdominal adhesion. This review outlines the preparation methods, mechanisms of action, and key applications of Janus hydrogel in the prevention of postoperative abdominal adhesions. Furthermore, we examine the current limitations of the Janus hydrogel anti-adhesion barrier and explore potential future directions for its development.

A self-fixing xanthan gum hydrogel membrane with ROS scavenging capability for the prevention of postoperative abdominal adhesion

Postoperative abdominal adhesions are a common complication of surgery and are caused by inflammation, tissue damage, and hypoxia. To address this issue, we prepared a SC-Xg hydrogel membrane by crosslinking xanthan gum (Xg) and sodium citrate (SC) through a dehydration condensation reaction with a crosslinking density of 39.4 %. Moreover, the mechanical performance of the SC-Xg hydrogel membrane could be enhanced by adjusting the concentration of SC. The 1.2-SC-Xg hydrogel membrane exhibited the highest stress resistance. The SC-Xg hydrogel membrane retains the excellent self-fixing ability, biocompatibility, and biodegradability of Xg while incorporating the antioxidant properties of SC. In vitro and in vivo experiments confirmed that the SC-Xg hydrogel membrane can completely cover irregular surgical sites and act as the most effective barrier against adhesions, fully exerting both physical and biological effects. Furthermore, molecular mechanism studies revealed that the hydrogel membrane primarily activated the Nrf2 signaling pathway in a concentration-dependent manner, enabling the SC-Xg hydrogel membrane to suppress postoperative oxidative stress reactions (ROS), reduce inflammation levels of IL-6 and TNF-α, reduce fibrosis, and effectively prevent the formation of abdominal adhesions. In conclusion, the SC-Xg hydrogel membrane represents a promising strategy for preventing postoperative abdominal adhesions.

Herbal HuoXueTongFu Formula with anti-inflammatory and fibrinolytic activity regulation for the prevention of postoperative peritoneal adhesions

Background

The HuoXueTongFu Formula (HXTF) originates from the classic prescription "DaHuangMuDan Decoction" from the "Synopsis of the golden chamber". Our previous study revealed that HXTF has a positive effect on postoperative peritoneal adhesion (PPA). However, the specific mechanism of HXTF on PPA formation within the time-to-treatment window has not been fully elucidated. This study aimed to determine the critical roles of HXTF as a result of its specific anti-inflammatory and antifibrinolytic activities for PPA treatment.

Methods

The eight main bioactive components of HXTF were subjected to high-performance liquid chromatography-mass spectrometry. The core targets, critical biological processes, and underlying pathways of HXTF and PPA were identified via a series of network pharmacological methods. The specific anti-inflammatory function in the initial step of PPA formation was validated in peritoneal macrophages (PMs) isolated from PPA mice on Day 3 postsurgery. The potential anti-fibrinolytic activity in the next stage of PPA formation was subsequently explored in PPA mice on Day 7 postsurgery.

Results

Network pharmacology revealed 160 common targets between HXTF and PPA. Several core targets, i.e., matrix metalloproteinase 9 (MMP9), tissue-type plasminogen activator (tPA), and plasminogen activator inhibitor 1 (PAI-1), were annotated as important biological processes (extracellular matrix disassembly and the collagen catabolic process). Validation experiments revealed that HXTF could induce macrophage polarization-mediated anti-inflammatory reactions by increasing the phagocytic capacity of PMs and promoting the release of anti-inflammatory cytokines (IL-4 and IL-10). In addition, HXTF promoted fibrinogenolysis and improved fibrinolytic activity, thereby inhibiting collagen deposition and reducing adhesion development.

Conclusion

The ameliorative effects of herbal HXTF on PPA formation are attributable to the induction of macrophage polarization-mediated anti-inflammatory reactions in the early stage of PPA formation and the promotion of fibrinogenolysis and fibrinolytic activity in the middle stage of PPA formation. HXTF may be a promising alternative agent for the prevention and treatment of PPA.

Crafting nature's wonders: nanoarchitectonics developments in bioinspired nanocellulose-based stimuli-responsive supramolecular matrices

Stimuli-responsive supramolecular assemblies have recently gained extensive attention in the biomedical field. Research focusing mainly on bioinspired functional supramolecular materials has shown great promise for potential drug delivery applications. Such materials can be engineered into 'smart' materials by utilizing various external stimuli such as pH, heat, light, and magnetic fields. Combining stimuli-responsive properties with bioinspired and biodegradable nanocellulose as a supramolecular matrix can offer a synergistic strategy for targeted and on-demand delivery of therapeutic drugs. The limitations of traditional drug delivery techniques may be greatly mitigated using this combination. In this review, we aim to provide a comprehensive overview of the recent advances in the development of stimuli-responsive nanocellulose-based drug delivery systems. Finally, we have highlighted the current challenges and future perspectives in the field, emphasizing the need for further research to overcome existing barriers and fully realize the potential of stimuli-responsive nanocellulose in drug-releasing applications. Reviewing the state-of-the-art developments and identifying critical areas for future exploration will provide valuable insights for researchers and practitioners working in nanomedicine and drug delivery, fostering the advancement of innovative and effective drug-releasing technologies.

Ligustrazine nanoparticles inhibits epithelial-mesenchymal transition and alleviates postoperative abdominal adhesion

Following abdominal surgery, the occurrence of postoperative abdominal adhesion (PAA) is highly prevalent and stands out as one of the most frequently encountered complications. The effect and molecular mechanisms of Ligustrazine nanoparticles (LN) underlying epithelial-mesenchymal transition (EMT) in PAA still remain elusive. Adhesions were induced in Male Sprague-Dawley rats by injuring the cecum (cecal abrasion model), followed by administration of LN and hyaluronate acid (HA). The mechanism was further verified by enzyme-linked immunosorbent assay, wound healing assay, si-RNA and Western blot. Animal experiments revealed that LN effectively ameliorated adhesions, notably decreased tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-8, and fibrosis, and reduced the expression of TGF-β1 and EMT related markers (Fibronectin and E-cadherin). Furthermore, in vitro experiments demonstrated that LN might inhibit the TGF-β1 FOXC2 pathway through suppressing the expression of Fibronectin, P120, and E-cadherin and ameliorating peritoneal adhesion. Collectively, our findings indicate that LN inhibits PAA formation by reducing inflammation, decreasing EMT and promoting peritoneal mesothelial cell repair. Therefore, LN might be considered a potential candidate for the treatment of PPA. However, further clinical studies are required to approve the effectiveness of LN.

Intra-peritoneal lavage of Zingiber officinale rhizome and its active constituent gingerol impede inflammation, angiogenesis, and fibrosis following post-operative peritoneal adhesion in male rats

Post-operative peritoneal adhesions (PA) are a common and important clinical problem. In this study, we focused on the ameliorative efficacy of ginger and gingerol compounds on surgical-induced peritoneal adhesion, and their strategies that disrupted the PA formation pathways to suppress their incidence. First, liquid chromatography-mass spectrometry (LC-MS) was established to separate and identify several chemical groups of ginger rhizome extract. In the next steps, male Wistar albino rats were randomly selected and divided into various groups, namely sham, control, ginger extract (0.6, 1.8, 5 %w/v), and gingerol (0.05, 0.1, 0.3, and 1 %w/v). Finally, we investigated the macroscopic parameters such as wound healing, body weight as well as spleen height and weight. In addition, visual peritoneal adhesion assessment was performed via Nair et al and Adhesion Scoring Scheme. Moreover, the microscopic parameters and biological assessment was performed via and immunoassays. The present findings revealed significant improvement in wound healing and reduction of the adhesion range, as Nair et al. and Adhesion Scoring Scheme scoring, in both the ginger and gingerol groups compared to the PA group (P < 0.05). Whereas, gingerol (0.3 % w/v) was able to increase the body weight in rats (P < 0.0001) at end stage of experiment. Also, inflammation, angiogenesis, and fibrosis were significantly decreased due to the downregulation of interleukin (IL)-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), respectively, in the ginger and gingerol groups compared to the PA group (P < 0.05). In contrast, the levels of IL-10 were increased in the ginger and gingerol groups compared to the control group (P < 0.01). Our results proved that ginger rhizome and gingerol, as novel therapeutic compounds, could be used to prevent PA for their beneficial anti-inflammatory as well as anti-fibrosis properties in clinical trials. However, further clinical studies are required to approve the effectiveness of ginger and gingerol.

Comparison of the effect of Everolimus, Prednisolone, and a combination of both on experimentally induced peritoneal adhesions in rats

Postoperative intra-abdominal adhesions represent a significant post-surgical problem. Its complications can cause a considerable clinical and cost burden. Herein, our study aimed to investigate the effect of Everolimus on peritoneal adhesion formation after inducing adhesions in rats. In this experimental study, adhesion bands were induced by intraperitoneal injection of 3 ml of 10% sterile talc solution in 64 male albino rats. The first group served as the control group. The second one received oral Prednisolone (1 mg/kg/day), the third received Everolimus (0.1 mg/kg/day), and group four received both drugs with similar dosages for four consecutive weeks. The formation of adhesion bands was qualitatively graded according to the Nair classification. The rats in the control group had extensive adhesions between the abdominal wall and the organs. Regarding substantial adhesion formation, 50% (8/16) of animals in the control group had substantial adhesions, while this rate in the groups receiving Prednisolone, Everolimus, and combination treatment was 31%, 31%, and 31%, respectively. Also, 68.75% (5/11) of the Prednisolone recipients had insubstantial adhesions, the same as Everolimus recipients, while in the combination group, 66.66% (10/15) rats had insubstantial adhesions. Everolimus demonstrated satisfactory results in reducing the rates of induced peritoneal adhesion in an experimental model, similar to Prednisolone and superior to a combination regime.

Hemoadhican-Based Bioabsorbable Hydrogel for Preventing Postoperative Adhesions

Postoperative peritoneal adhesions are a prevalent clinical issue following abdominal and pelvic surgery, frequently resulting in heightened personal and societal health burdens. Traditional biomedical barriers offer limited benefits because of practical challenges for doctors and their incompatibility with laparoscopic surgery. Hydrogel materials, represented by hyaluronic acid gels, are receiving increasing attention. However, existing antiadhesive gels still have limited effectiveness or carry the risk of complications in clinical applications. Herein, we developed a novel hydrogel using polysaccharide hemoadhican (HD) as the base material and polyethylene glycol diglycidyl ether (PEGDE) as the cross-linking agent. The HD hydrogels exhibit appropriate mechanical properties, injectability, and excellent cytocompatibility. We demonstrate resistance to protein adsorption and L929 fibroblast cell adhesion to the HD hydrogel. The biodegradability and efficacy against peritoneal adhesion are further evaluated in C57BL/6 mice. Our results suggest a potential strategy for anti-postoperative tissue adhesion barrier biomaterials.

Injectable Multifunctional Composite Hydrogel as a Combination Therapy for Preventing Postsurgical Adhesion

Postsurgical adhesion (PA) is a common and serious postoperative complication that affects millions of patients worldwide. However, current commercial barrier materials are insufficient to inhibit diverse pathological factors during PA formation, and thus, highly bioactive materials are needed. Here, this work designs an injectable multifunctional composite hydrogel that can serve as a combination therapy for preventing PA. In brief, this work reveals that multiple pathological events, such as chronic inflammatory and fibrotic processes, contribute to adhesion formation in vivo, and such processes can not be attenuated by barrier material (e.g., hydrogel) alone treatments. To solve this limitation, this work designs a composite hydrogel made of the cationic self-assembling peptide KLD2R and TGF-β receptor inhibitor (TGF-βRi)-loaded mesenchymal stem cell-derived nanovesicles (MSC-NVs). The resulting composite hydrogel displays multiple functions, including physical separation of the injured tissue areas, antibacterial effects, and local delivery and sustained release of anti-inflammatory MSC-NVs and antifibrotic TGF-βRi. As a result, this composite hydrogel effectively inhibited local inflammation, fibrosis and adhesion formation in vivo. Moreover, the hydrogel also exhibits good biocompatibility and biodegradability in vivo. Together, the results highlight that this "all-in-one" composite hydrogel strategy may provide insights into designing advanced therapies for many types of tissue injury.

Degradable carrier-free spray hydrogel based on self-assembly of natural small molecule for prevention of postoperative adhesion

Postoperative peritoneal adhesion (PPA) is frequent and extremely dangerous complication after surgery. Different tactics have been developed to reduce it. However, creating a postoperative adhesion method that is multifunctional, biodegradable, biocompatible, low-toxic but highly effective, and therapeutically applicable is still a challenge. Herein, we have prepared a degradable spray glycyrrhetinic acid hydrogel (GAG) based on natural glycyrrhetinic acid (GA) by straightforward heating and cooling without the use of any additional chemical cross-linking agents to prevent postoperative adhesion. The resultant hydrogel was demonstrated to possess various superior anti-inflammatory activity, and multiple functions, such as excellent degradability and biocompatibility. Specifically, spraying characteristic and excellent antibacterial activities essentially eliminated secondary infections during the administration of drugs in surgical wounds. In the rat models, the carrier-free spray GAG could not only slow-release GA to inhibit inflammatory response, but also serve as physical anti-adhesion barrier to reduce collagen deposition and fibrosis. The sprayed GAG would shed a new light on the prevention of postoperative adhesion and broaden the application of the hydrogels based on natural products in biomedical fields.

Carbon monoxide (CO) derived from the CO-releasing molecule CORM-2 reduces peritoneal adhesion formation in a rat model

BACKGROUND

Although low-dose carbon monoxide (CO) administration has been shown to have an anti-fibrotic effect in various fibrotic diseases, its effects on peritoneal adhesion (PA), one of the postoperative complications, are not elucidated. In this study, the effect of CO-releasing tricarbonyldichlororuthenium (II) dimer (CORM-2) administration on the formation of PA and the underlying factors of its potential effect were investigated.

METHODS AND RESULTS

After the induction of PA, rats were divided into four groups with 8 rats in each group. The rats received either (i) dimethyl sulfoxide:saline solution (1:10) as a vehicle, (ii) 2.5 mg/kg CORM-2, (iii) 5 mg/kg CORM-2, or (iv) inactive (i) CORM (iCORM) intragastrically every day for a duration of 7 days. PA was not induced in rats (n = 8) designated as sham controls. Gross, histological, immunohistochemical and quantitative real-time polymerase chain reaction analyses were performed to evaluate the effectiveness of CORM-2 administration. Gross analysis showed that CORM-2 administration reduced PA formation compared to rats treated with vehicle. Histological and immunohistochemical examinations showed that increased collagen deposition, myofibroblast accumulation, microvessel density, and M1 macrophage count in the peritoneal fibrosis area of vehicle-treated rats decreased following CORM-2 treatments. PCR analyses showed that CORM-2 treatments decreased hypoxia-induced Hif1a, profibrotic Tgfb1, ECM components Col1a1 and Col3a1, collagen degradation suppressor Timp1, fibrinolysis inhibitor Serpine1, and pro-inflammatory Tnf mRNA expressions, while increasing the M2 macrophage marker Arg1 mRNA expression.

CONCLUSIONS

These results suggested that CORM-2 administration reduces PA formation by affecting adhesiogenic processes such as pro-inflammatory response, fibrinolytic system, angiogenesis and fibrogenesis.

Outcome of early versus late ileostomy closure in patients with rectal cancers undergoing low anterior resection: A prospective cohort study

BACKGROUND

Protective loop ileostomy is performed following low anterior resection (LAR) in patients with rectal cancer to reduce the complications of primary anastomosis. The optimal timing for ileostomy closure remains controversial. The aim of the current study was to compare the effects of early (<2 weeks) versus late (≥2 months) closure of the stoma in patients with rectal cancer undergoing LAR on surgical outcome and complications rates.

METHODS

This prospective cohort study was conducted in two referral centers in Shiraz, Iran, during a 2-year period. We have consecutively and prospectively included adult patients with rectal adenocarcinoma who underwent LAR followed by protective loop ileostomy in our center during the study period. The baseline, tumor characteristics and complication as well as outcome was recorded in a 1-year follow-up and was compared between early and late ileostomy closure.

RESULTS

Overall, 69 patients (32 in early and 37 in late group) were included. The mean age of the patients was 59.40 ± 9.30 years and there were 46 (66.7%) men and 23 (33.3%) women. Patients undergoing early closure of the ileostomy had significantly shorter operation duration (p<0.001) and lower intraoperative bleeding (p<0.001) compared to late ileostomy closure. There was no significant difference between two study groups regarding the complications. Early closure was also not found to be a predictive factor of post-ileostomy closure complications.

CONCLUSION

Early closure (<2 weeks) of ileostomy after LAR in patients with rectal adenocarcinoma is a safe and feasible technique which is associated with favorable outcome.

Analysis of abdominal adhesion using the ileostomy model

Abdominal adhesion occurs commonly in clinical practice, causing unfavorable symptoms and readmission. The ileostomy operation is a common surgical procedure and we utilized this model to evaluate abdominal adhesion. Adhesion grade score was calculated in 35 patients (Cohort 1) and subjected to correlation and receiver operating characteristic analysis. Then 98 consecutive patients (Cohort 2) who underwent ileostomy and ileostomy closure were included into a retrospective study. Logistic regression analysis was performed, and the risk of small bowel obstruction was also assessed. The time of ileostomy closure correlated with adhesion grade score in Cohort 1, justifying its use as an indicator of abdominal adhesion. All patients in Cohort 2 were then divided into the high- and low-adhesion group. A multi-variable logistic regression analysis indicated that type of surgery and peritoneum suture during ileostomy were significant factors affecting the risk of abdominal adhesion. Abdominal adhesion had the trend to prolong the length of stay postoperatively without increasing the risk of bowel obstruction. Nine patients suffered bowel obstruction, and age older than 65 significantly increased the risk. We proposed the ileostomy procedure to be a model of abdominal adhesion, and the operative time of ileostomy closure could be used as an alternative of adhesion score. Type of surgery and peritoneum suture may be risk factors of abdominal adhesion. Older age increased the risk of small bowel obstruction after ileostomy surgery.

Oral Administration Evaluation of the Hydro-Ethanolic Extract of Ginger (Rhizome of Zingiber officinale) against Postoperative-Induced Peritoneal Adhesion: Investigating the Role of Anti-Inflammatory and Antioxidative Effects

Peritoneal adhesions (PAs) occur and develop after abdominal surgery. Abdominal adhesions are common and often develop after abdominal surgery. Currently, there are no effective targeted pharmacotherapies for treating adhesive disease. In this regard, ginger is wildly used in traditional medicine because of its anti-inflammatory and antioxidant effects and has been investigated for peritoneal adhesion treatment. This study analyzed ginger ethanolic extraction via HPLC to have a 6-gingerol concentration. Four groups induced peritoneal adhesion to evaluate ginger's effects on peritoneal adhesion. Then, ginger extract (50, 150, and 450 mg/kg) was administered by gavage in various groups of male Wistar rats (220 ± 20 g, 6-8 weeks). After scarifying the animals for biological assessment, macroscopic and microscopic parameters were determined via scoring systems and immunoassays in the peritoneal lavage fluid. Next, the adhesion scores and interleukin IL-6, IL-10, tumor necrosis factor-(TNF-) α, transforming growth factor-(TGF-) β1, vascular endothelial growth factor (VEGF), and malondialdehyde (MDA) were elevated in the control group. The results showed that ginger extract (450 mg/kg) notably decreased inflammatory (IL-6 and TNF-α), fibrosis (TGF-β1), anti-inflammatory cytokine (IL-10), angiogenesis (VEGF), and oxidative (MDA) factors, while increased antioxidant factor glutathione (GSH), compared to the control group. These findings suggest that a hydro-alcoholic extract of ginger is a potentially novel therapeutic strategy for inhibiting adhesion formation. Also, it might be considered a beneficial anti-inflammatory or antifibrosis herbal medicine in clinical trials. However, further clinical studies are required to approve the effectiveness of ginger.

The preventive effect of omega-3 fish oil on the formation of peritoneal adhesions

<br><b>Introduction:</b> Postoperative peritoneal adhesions that form after abdominal surgery still continue to exist as an unresolved health problem.</br> <br><b>Aim:</b> The aim of the study is to examine whether omega-3 fish oil has a preventive effect on postoperative peritoneal adhesions.</br> <br><b>Material and methods:</b> Twenty-one female Wistar albino rats were separated into 3 groups (sham, control and experimental), each consisting of 7 rats. In the sham group, only laparotomy was performed. In both the control and experimental group rats, the right parietal peritoneum and cecum were traumatised to form petechiae. Following this procedure, the abdomen was irrigated with omega-3 fish oil in the experimental group. The rats were re-explored on the 14^th postoperative day and any adhesions were scored. Tissue samples and blood samples were taken for histopathological and biochemical analysis.</br> <br><b>Results:</b> None of the rats that were administered omega-3 fish oil developed macroscopic postoperative peritoneal adhesions (P = 0.005). The omega-3 fish oil formed an anti-adhesive lipid barrier on the injured tissue surfaces. Microscopic evaluation revealed diffuse inflammation with excessive connective tissue and fibroblastic activity in the control group rats, while foreign body reactions were common in the omega-3 rats. The mean amount of hydroxyproline in samples from injured tissues was significantly lower in the omega-3 rats than in the control rats (P = 0.004).</br> <br><b>Conclusion:</b> Intraperitoneal application of omega-3 fish oil prevents postoperative peritoneal adhesions by forming an anti-adhesive lipid barrier on injured tissue surfaces. However, further studies are needed to determine whether this adipose layer is permanent or will be resorbed over time.</br>.

Exploring new therapeutic potentials of curcumin against post-surgical adhesion bands

BACKGROUND

Adhesion band formation is a common cause of morbidity for patients undergoing surgeries. Anti-inflammatory and anti-fibrotic properties of curcumin, a pharmacologically active component of Curcuma longa, have been investigated in several studies. The aim of this study is to explore the therapeutic potential of curcumin in attenuating post-operative adhesion band (PSAB) formation in both peritoneal and peritendinous surgeries in animal models.

METHODS

Bio-mechanical, histological and quantitative evaluation of inflammation, and total fibrosis scores were graded and measured in the presence and absence of phytosomal curcumin.

RESULTS

Results showed that phytosomal curcumin significantly decreased severity, length, density and tolerance of mobility of peritendinous adhesions as well as incidence and severity of abdominal fibrotic bands post-surgery. Curcumin may decrease inflammation by attenuating recruitment of inflammatory cells and regulating oxidant/anti-oxidant balance in post-operative tissue samples. Moreover, markedly lower fibrosis scores were obtained in the adhesive tissues of phytosomal curcumin-treated groups which correlated with a significant decrease in quantity, quality and grading of fibers, and collagen deposition in animal models.

CONCLUSION

These results suggest that protective effects of phytosomal curcumin against PSAB formation is partially mediated by decreasing inflammation and fibrosis at site of surgery. Further studies are needed to investigate the therapeutic potential of this molecule in preventing PSAB.

Punica granatum seed oil detracts peritoneal adhesion: Perusing antioxidant, anti-inflammatory, antifibrotic, and antiangiogenic impacts

Peritoneal adhesion is a significant problem following gastrointestinal surgeries, accompanied by a significant economic burden and morbidity for patients. Punica granatum seed oil (PSO) possesses antioxidative, anti-inflammatory, and anticancer effects. Thus, we aimed to evaluate the antiperitoneal adhesive properties of PSO in rats. Forty-eight Wistar rats (200-250 g) were randomly and equally divided into six groups: sham group, control group; peritoneal adhesion without any treatment, vehicle group; peritoneal adhesion with saline + Tween-80.5% treatment, and experimental groups; peritoneal adhesion with 0.5%, 1.5%, and 4.5% v/v PSO treatment. In addition, peritoneal adhesion was examined macroscopically along with evaluating the oxidative stress (malondialdehyde [MDA], nitric oxide [NO], and glutathione [GSH]) inflammatory (interleukin [IL]-6, IL-1β, and tumor necrosis factor-α [TNF-α]), fibrotic (transforming growth factor-β [TGF-β]), and angiogenic (vascular endothelial growth factor [VEGF]) factors. Our results revealed that the levels of adhesion scores, MDA, NO, IL-6, TNF-α, IL-1β, TGF-β, and VEGF, were propagated in the vehicle group while the GSH level was alleviated (p < 0.001). In contrast, premedication with PSO, especially at the lowest concentration, notably lessened the levels of adhesion scores, MDA, NO, IL-6, TNF-α, IL-1β, TGF-β, and VEGF as well as GSH in comparison to the vehicle group following the peritoneal adhesion induction (p < 0.001-0.05). As a result, PSO may prevent peritoneal adhesion through its antioxidant, anti-inflammatory, antifibrotic, and antiangiogenic properties. Therefore, PSO could be considered a beneficial candidate for the treatment of postoperative peritoneal adhesion.

Bottlebrush inspired injectable hydrogel for rapid prevention of postoperative and recurrent adhesion

Postsurgical adhesion is a common clinic disease induced by surgical trauma, accompanying serious subsequent complications. Current non-surgical approaches of drugs treatment and biomaterial barrier administration only show limited prevention effects and couldn't effectively promote peritoneum repair. Herein, inspired by bottlebrush, a novel self-fused, antifouling, and injectable hydrogel is fabricated by the free-radical polymerization in aqueous solution between the methacrylate hyaluronic acid (HA-GMA) and N-(2-hydroxypropyl) methacrylamide (HPMA) monomer without any chemical crosslinkers, termed as H-HPMA hydrogel. The H-HPMA hydrogel can be tuned to perform excellent self-fused properties and suitable abdominal metabolism time. Intriguingly, the introduction of the ultra-hydrophilic HPMA chains to the H-HPMA hydrogel affords an unprecedented antifouling capability. The HPMA chains establish a dense hydrated layer that rapidly prevents the postsurgical adhesions and recurrent adhesions after adhesiolysis in vivo. The H-HPMA hydrogel can repair the peritoneal wound of the rat model within 5 days. Furthermore, an underlying mechanism study reveals that the H-HPMA hydrogel significantly regulated the mesothelial-to-mesenchymal transition (MMT) process dominated by the TGF-β-Smad2/3 signal pathway. Thus, we developed a simple, effective, and available approach to rapidly promote peritoneum regeneration and prevent peritoneal adhesion and adhesion recurrence after adhesiolysis, offering novel design ideas for developing biomaterials to prevent peritoneal adhesion.

Activating SIRT3 in peritoneal mesothelial cells alleviates postsurgical peritoneal adhesion formation by decreasing oxidative stress and inhibiting the NLRP3 inflammasome

Peritoneal adhesions (PAs) are a serious complication of abdominal surgery and negatively affect the quality of life of millions of people worldwide. However, a clear molecular mechanism and a standard therapeutic strategy for PAs have not been established. Here, we developed a standardized method to mimic the pathological changes in PAs and found that sirtuin 3 (SIRT3) expression was severely decreased in adhesion tissues, which was consistent with our bioinformatics analysis and patient adhesion tissue analysis. Thus, we hypothesized that activating SIRT3 could alleviate postsurgical PAs. Sirt3-deficient (Sirt3^−/−) mice exhibited many more PAs after standardized abdominal surgery. Furthermore, compared with wild-type (Sirt3^+/+) mice, Sirt3-deficient (Sirt3^−/−) mice showed more prominent reactive oxygen species (ROS) accumulation, increased levels of inflammatory factors, and exacerbated mitochondrial damage and fragmentation. In addition, we observed NLRP3 inflammasome activation in the adhesion tissues of Sirt3^−/− but, not Sirt3^+/+ mice. Furthermore, mesothelial cells sorted from Sirt3^−/− mice exhibited impaired mitochondrial bioenergetics and redox homeostasis. Honokiol (HKL), a natural compound found in several species of the genus Magnolia, could activate SIRT3 in vitro. Then, we demonstrated that treatment with HKL could reduce oxidative stress and the levels of inflammatory factors and suppress NLRP3 activation in vivo, reducing the occurrence of postsurgical PAs. In vitro treatment with HKL also restored mitochondrial bioenergetics and promoted mesothelial cell viability under oxidative stress conditions. Taken together, our findings show that the rescue of SIRT3 by HKL may be a new therapeutic strategy to alleviate and block postsurgical PA formation.

Treatment with honokiol, a compound found in magnolia tree bark, significantly reduces formation of internal scar tissue after abdominal surgery in mice. Healing of incisions in the peritoneum, the connective tissue lining the abdomen, can result in scar tissue bonds known as peritoneal adhesions (PA), causing complications such as infertility or bowel obstructions. The mechanism of PA formation is unknown, and no therapies are available. Xuqi Li at The First Affiliated Hospital of Xi’an Jiaotong University, China, and co-workers found that PA tissues in both mice and human patients had decreased levels of SIRT3, a stress-response protein. Mice lacking SIRT3 showed increased inflammation and PA formation. When mice were treated with honokiol the day after surgery in order to boost SIRT3 levels, PA formation was significantly decreased. These results suggest a possible preventative treatment for post-surgical PAs.

Regenerative Medicine Therapies for Prevention of Abdominal Adhesions: A Scoping Review

INTRODUCTION

Globally, abdominal adhesions constitute a significant burden of morbidity and mortality. They represent the commonest complication of abdominal operations with a lifelong risk of multiple pathologies, including adhesive small bowel obstruction, female infertility, and chronic pain. Adhesions represent a problem of the entire abdomen, forming at the time of injury and progressing through multiple complex pathways. Clinically available preventative strategies are limited to barrier technologies. Significant knowledge gaps persist in the characterization and mitigation of the involved molecular pathways underlying adhesion formation. Thus, the objectives of this scoping review are to describe the known molecular pathophysiology implicated in abdominal adhesion formation and summarize novel preclinical regenerative medicine preventative strategies for potential future clinical investigation.

METHODS

A literature review was performed in accordance with the Preferred Reporting Items for Systematic Reviews Extension for Scoping Reviews. Included peer-reviewed publications were published within the last 5 y and contained in vivo preclinical experimental studies of postoperative adhesions with the assessment of underlying mechanisms of adhesion formation and successful therapy for adhesion prevention. Studies not involving regenerative medicine strategies were excluded. Data were qualitatively synthesized.

RESULTS

A total of 1762 articles were identified. Of these, 1001 records were excluded by the described screening criteria. Sixty-eight full-text articles were evaluated for eligibility, and 11 studies were included for review.

CONCLUSIONS

Novel and reliable preventative strategies are urgently needed. Recent experimental data propose novel regenerative medicine targets for adhesion prevention.

Prevention of postoperative adhesion with a colloidal gel based on decyl group-modified Alaska pollock gelatin microparticles

Postoperative adhesion, bonding of the abdominal wall to damaged organs, causes severe complications after abdominal surgery. Despite the availability of physical barriers (i.e., solutions, films, and hydrogels), adhesion prevention materials that are a single-substance system with stability in wet tissue and ease of use have not been reported. Here, we report a microparticle based, sprayable adhesion prevention material comprising decyl group modified Alaska pollock gelatin (C10-ApGltn). C10-ApGltn microparticles (C10-MPs) were prepared by a coacervation method, freeze drying, and thermal crosslinking. The C10-MPs adhered to and formed a colloidal gel layer on intestinal serosal tissue by hydration without any crosslinking agents. After hydration of the C10-MPs, the resulting colloidal gel layer did not adhere to other tissues. Additionally, the C10-MP colloidal gel layer formed on the stomach serosal tissue showed stability when submersed in saline for 2 days. The colloidal gel layer also showed tissue followability. An in vivo rat adhesion model revealed that C10-MP colloidal gel layer on the cecum and abdominal wall defects effectively reduced postoperative adhesion and induced tissue remodeling, including re-mesothelialization. Therefore, C10-MPs are a potential anti-adhesion material for preventing postoperative adhesion. STATEMENT OF SIGNIFICANCE: We evaluated the postoperative adhesion prevention ability of a colloidal gel based on decyl group modified Alaska pollock gelatin (ApGltn) microparticles (C10-MPs). These microparticles are sprayable and form a colloidal gel with only hydration on the gastrointestinal tissue. We revealed that the modification of the decyl group into ApGltn improved the stability of C10-MP colloidal gel on the tissue by hydrophobic interaction in the in-vitro experiments. The gel prevented postoperative adhesion by being a physical barrier in the in-vivo rat adhesion model.

Comparison of Oral Sirolimus, Prednisolone, and Combination of Both in Experimentally Induced Peritoneal Adhesion

INTRODUCTION

Peritoneal adhesion formation is a challenging postoperative complication. We aim to evaluate the effect of orally administered sirolimus, prednisolone, and their combination to prevent this entity.

METHODS

Eighty female albino underwent intraperitoneal injection of 3 mL of 10% sterile talc solution to induce peritoneal adhesion, and were subsequently and randomly divided into four groups (each n = 20); including a control group; 1 mg/kg oral prednisolone daily in the morning; 0.1 mg/kg oral sirolimus daily; and a combination group which received both drugs, with the same dosage. On the 29th day, abdominal cavities were explored, and classification was done based on Nair classification.

RESULTS

All rats were healthy on the 29th day, in which exploration was performed. The rats in the control group had extensive intra-abdominal adhesions, while 17 (85%) rats in the control group had substantial adhesion; however, the prednisolone, sirolimus, and combination group had lesser adhesion formation. Also, 14 (70%) rats of prednisolone group, 13 (65%) of sirolimus group, and 16 (80%) of combination group had insubstantial adhesion. The decrease in the grade of peritoneal adhesion bands was highly significant in the combination group (P > 0.001).

CONCLUSIONS

The combination of sirolimus and prednisolone was effective for preventing peritoneal adhesions in rats.

Nanoengineered Shear-Thinning Hydrogel Barrier for Preventing Postoperative Abdominal Adhesions

More than 90% of surgical patients develop postoperative adhesions, and the incidence of hospital re-admissions can be as high as 20%. Current adhesion barriers present limited efficacy due to difficulties in application and incompatibility with minimally invasive interventions. To solve this clinical limitation, we developed an injectable and sprayable shear-thinning hydrogel barrier (STHB) composed of silicate nanoplatelets and poly(ethylene oxide). We optimized this technology to recover mechanical integrity after stress, enabling its delivery though injectable and sprayable methods. We also demonstrated limited cell adhesion and cytotoxicity to STHB compositions in vitro. The STHB was then tested in a rodent model of peritoneal injury to determine its efficacy preventing the formation of postoperative adhesions. After two weeks, the peritoneal adhesion index was used as a scoring method to determine the formation of postoperative adhesions, and STHB formulations presented superior efficacy compared to a commercially available adhesion barrier. Histological and immunohistochemical examination showed reduced adhesion formation and minimal immune infiltration in STHB formulations. Our technology demonstrated increased efficacy, ease of use in complex anatomies, and compatibility with different delivery methods, providing a robust universal platform to prevent postoperative adhesions in a wide range of surgical interventions.

Anti-Adhesion Effect of Composite Film Materials Based on Glycoluril-Modified Sodium Carboxymethyl Cellulose

The aim of the study was to develop composite film materials derived from modified sodium carboxymethyl cellulose and to evaluate their anti-adhesive effects.