Human peritoneal adhesions are highly cellular, innervated, and vascularized

Endogenously produced hyaluronan contributes to the regulation of peritoneal adhesion development

Peritoneal adhesions are postsurgical fibrotic complications connected to peritoneal inflammation. The exact mechanism of development is unknown; however, an important role is attributed to activated mesothelial cells (MCs) overproducing macromolecules of extracellular matrix (ECM), including hyaluronic acid (HA). It was suggested that endogenously-produced HA contributes to the regulation of different fibrosis-related pathologies. However, little is known about the role of altered HA production in peritoneal fibrosis. We focused on the consequences of the increased turnover of HA in the murine model of peritoneal adhesions. Changes of HA metabolism were observed in early phases of peritoneal adhesion development in vivo. To study the mechanism, human MCs MeT-5A and murine MCs isolated from the peritoneum of healthy mice were pro-fibrotically activated by transforming growth factor β (TGFβ), and the production of HA was attenuated by two modulators of carbohydrate metabolism, 4-methylumbelliferone (4-MU) and 2-deoxyglucose (2-DG). The attenuation of HA production was mediated by upregulation of HAS2 and downregulation of HYAL2 and connected to the lower expression of pro-fibrotic markers, including fibronectin and α-smooth muscle actin (αSMA). Moreover, the inclination of MCs to form fibrotic clusters was also downregulated, particularly in 2-DG-treated cells. The effects of 2-DG, but not 4-MU, were connected to changes in cellular metabolism. Importantly, the inhibition of AKT phosphorylation was observed after the use of both HA production inhibitors. In summary, we identified endogenous HA as an important regulator of peritoneal fibrosis, not just a passive player during this pathological process.

HPLC/MS characterization of Syzygium aromaticum L. and evaluation of its effects on peritoneal adhesion: Investigating the role of inflammatory cytokines, oxidative factors, and fibrosis and angiogenesis biomarkers

The dried flower bud of Syzygium aromaticum L. (S. aromaticum) (Myrtaceae), cloves, have been used for their analgesic and anti-inflammatory activities. Peritoneal adhesion (PA) is the most common complication of abdominal and pelvic surgeries, which causes significant adverse effects and severe economic burden. The present study aimed to evaluate the preventive effect of S. extract (SAE) on PA formation in a rat model. Male Wistar 8-week-old rats were randomly divided into sham, control (received vehicle), and treatment (0.25%, 0.5%, and 1% w/v of SAE) groups. The adhesion and related factors were examined using the Nair scoring system and immunological and biochemical kits for the levels of inflammatory cytokines [interleukin (IL)-6 and tumor necrosis factor (TNF)-α], growth factors [transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF)], oxidative [nitric oxide (NO) and malondialdehyde (MDA)], and anti-oxidative [glutathione (GSH)] factors. Our results figured out that the adhesion score and IL-6, TNF-α, TGF-β1, VEGF, NO, and MDA levels were significantly increased, but the GSH level was decreased in the control group compared to the sham group (p < 0.001-0.05). On the other hand, the 0.25% SAE group had a lower adhesion score, and IL-6, TNF-α, TGF-β1, VEGF, NO, and MDA levels were significantly decreased compared with the vehicle group, and the level of GSH was increased (p < 0.001-0.05). SAE could efficiently reduce adhesion score and regulate inflammatory cytokines, oxidative and anti-oxidative factors, and biomarkers of fibrosis and angiogenesis. Therefore, clove extract can be considered a potential candidate for PA management.

Analgesia in patients with adhesion-related chronic abdominal and pelvic pain after surgery: a systematic review

BACKGROUND AND OBJECTIVE

Adhesions are the most common cause of chronic abdominal pain after surgery. Surgical adhesiolysis can relieve symptoms in selected patients, but many require other treatments. The aim of this study is to evaluate analgesic treatments other than abdominal surgery in chronic pain related to adhesions.

DATABASE AND DATA TREATMENT

A search was conducted in PubMed, Embase, and Central. Studies with patients suffering from chronic postoperative pain related to adhesions and undergoing all types' analgesic treatment were included. The primary outcome was the number of patients who improved in pain at long-term follow-up (at least 1 year). Secondary outcomes included improvement in pain at 3 months follow-up, quality of life, and physical functioning.

RESULTS

Searches identified 3022 citations. Four studies were included, one trial, one cohort study, and two case reports. The primary outcome was not reported. In a small trial (n = 18) pregabalin tended to have a benefit over placebo improving pain at 3 months. In the cohort study, 17 patients with chronic pelvic pain underwent a trial of sacral nerve stimulation. Eight patients who responded positively received an implanted device for continuous modulation, reporting sustainable improvement during follow-up (range: 6-36 months). One case report described improved pain at 6 months with trans-abdominis plane stimulation. The second report described improvement of physical function with manual therapy at long-term follow-up.

CONCLUSIONS

Low level of evidence is available regarding analgesic treatments of chronic abdominal and pelvic pain related to adhesions. The benefit of pregabalin is doubtful; nerve modulation is promising in a selected group.HighlightsAdhesions are a frequent cause of chronic abdominal and pelvic pain after surgery.Many patients are not good candidates for surgery (Adhesiolysis) or have relapses of pain.There is an important knowledge gap regarding non-surgical analgesic treatment.Analgesia in adhesion-related chronic abdominal pain after surgery.

What is the precaecocolic fascia?

The precaecocolic fascia, previously known as Jackson's membrane, is a variable vascular peritoneal fold between the ascending colon and the right posterolateral abdominal wall. First described in 1913, it was originally thought to be of developmental or inflammatory origin and associated with abdominal pain. This investigation aimed to review its frequency, form and structure and look for evidence of association with malformation of the bowel, or previous inflammation. 26 dissecting room cadavers were studied to identify the precaecocolic fascia, any malrotation of the colon or signs of previous inflammation: adhesions, surgical scars, or absence of the appendix. Its structure was examined histologically and latex injections were used to trace the arteries. Membranes comparable with previous descriptions of the precaecocolic fascia occurred in 12 of 26 abdomens. They varied in form and size from long and translucent to short, thick, and opaque. In structure, the fascia resembled a fold of peritoneum containing a thickened fibrous lamina. Large thin-walled arteries in the fascia crossed the arteries in the wall of the colon at the point of attachment. No significant association with colonic malrotation or markers of previous inflammation were found. Attention should be paid to the definition of the precaecocolic fascia and "membrane" seems a more appropriate term than "fascia". It is one of a recognized group of peritoneal folds/bands, doubtful in origin but unlikely to be post-inflammatory. It may modify colonic mobility or complicate colonic operations.

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.

Sterile Injury Repair and Adhesion Formation at Serosal Surfaces

Most multicellular organisms have a major body cavity containing vital organs. This cavity is lined by a mucosa-like serosal surface and filled with serous fluid which suspends many immune cells. Injuries affecting the major body cavity are potentially life-threatening. Here we summarize evidence that unique damage detection and repair mechanisms have evolved to ensure immediate and swift repair of injuries at serosal surfaces. Furthermore, thousands of patients undergo surgery within the abdominal and thoracic cavities each day. While these surgeries are potentially lifesaving, some patients will suffer complications due to inappropriate scar formation when wound healing at serosal surfaces defects. These scars called adhesions cause profound challenges for health care systems and patients. Therefore, reviewing the mechanisms of wound repair at serosal surfaces is of clinical importance. Serosal surfaces will be introduced with a short embryological and microanatomical perspective followed by a discussion of the mechanisms of damage recognition and initiation of sterile inflammation at serosal surfaces. Distinct immune cells populations are free floating within the coelomic (peritoneal) cavity and contribute towards damage recognition and initiation of wound repair. We will highlight the emerging role of resident cavity GATA6+ macrophages in repairing serosal injuries and compare serosal (mesothelial) injuries with injuries to the blood vessel walls. This allows to draw some parallels such as the critical role of the mesothelium in regulating fibrin deposition and how peritoneal macrophages can aggregate in a platelet-like fashion in response to sterile injury. Then, we discuss how serosal wound healing can go wrong, causing adhesions. The current pathogenetic understanding of and potential future therapeutic avenues against adhesions are discussed.

Post-Surgical Peritoneal Scarring and Key Molecular Mechanisms

Post-surgical adhesions are internal scar tissue and a major health and economic burden. Adhesions affect and involve the peritoneal lining of the abdominal cavity, which consists of a continuous mesothelial covering of the cavity wall and majority of internal organs. Our understanding of the full pathophysiology of adhesion formation is limited by the fact that the mechanisms regulating normal serosal repair and regeneration of the mesothelial layer are still being elucidated. Emerging evidence suggests that mesothelial cells do not simply form a passive barrier but perform a wide range of important regulatory functions including maintaining a healthy peritoneal homeostasis as well as orchestrating events leading to normal repair or pathological outcomes following injury. Here, we summarise recent advances in our understanding of serosal repair and adhesion formation with an emphasis on molecular mechanisms and novel gene expression signatures associated with these processes. We discuss changes in mesothelial biomolecular marker expression during peritoneal development, which may help, in part, to explain findings in adults from lineage tracing studies using experimental adhesion models. Lastly, we highlight examples of where local tissue specialisation may determine a particular response of peritoneal cells to injury.

Spectrum of CT Findings Related to Bowel Adhesions Without Bowel Obstruction: A Comprehensive Imaging Review

Post-operative adhesions can occur following abdominal or pelvic surgery and are a significant cause of morbidity and mortality. Adhesions are an important cause of abdominal complaints, especially chronic abdominal pain, infertility, and bowel obstruction; responsible for an estimated $2.3 billion annual burden in the United States alone. There is a paucity of literature describing CT findings indicative of the presence of adhesions, however, findings suggestive of this entity may be discovered by a discerning eye. Early recognition and diagnosis may be beneficial for reducing consumption of health-care resources related to abdominal complaints. In addition, these findings may impact surgical planning and facilitate recognition of adhesion-related complications, said to be responsible for a significant number of malpractice claims. The following review discusses various CT findings which may indicate the presence of adhesions. These findings may initially be overlooked, but remain valuable as the clinical presentation evolves to become consistent with adhesive disease. Detection of bowel and peritoneal adhesions can be recognized on imaging modalities based on distortion of bowel loops. This pictorial review illustrates the spectrum of findings related to bowel adhesions encountered on computed tomography imaging.

Mesothelial Cells Participate in Endometriosis Fibrogenesis Through Platelet-Induced Mesothelial-Mesenchymal Transition

CONTEXT

While fibrosis in endometriosis has recently loomed prominently, the sources of myofibroblasts, the principal effector cell in fibrotic diseases, remain largely obscure. Mesothelial cells (MCs) can be converted into myofibroblasts through mesothelial-mesenchymal transition (MMT) in many fibrotic diseases and adhesion.

OBJECTIVE

To evaluate whether MCs contribute to the progression and fibrogenesis in endometriosis through MMT.

SETTING, DESIGN, PATIENTS, INTERVENTION, AND MAIN OUTCOME MEASURES

Dual immunofluorescence staining and immunohistochemistry using antibodies against calretinin, Wilms' tumor-1 (WT-1), and α-smooth muscle actin (α-SMA) were performed on lesion samples from 30 patients each with ovarian endometrioma (OE) and deep endometriosis (DE), and 30 normal endometrial (NE) tissue samples. Human pleural and peritoneal MCs were co-cultured with activated platelets or control medium with and without neutralization of transforming growth factor β1 (TGF-β1) and/or platelet-derived growth factor receptor (PDGFR) and their morphology, proliferation, and expression levels of genes and proteins known to be involved in MMT were evaluated, along with their migratory and invasive propensity, contractility, and collagen production.

RESULTS

The number of calretinin/WT-1 and α-SMA dual-positive fibroblasts in OE/DE lesions was significantly higher than NE samples. The extent of lesional fibrosis correlated positively with the lesional α-SMA staining levels. Human MCs co-cultured with activated platelets acquire a morphology suggestive of MMT, concomitant with increased proliferation, loss of calretinin expression, and marked increase in expression of mesenchymal markers. These changes coincided with functional differentiation as reflected by increased migratory and invasive capacity, contractility, and collagen production. Neutralization of TGF-β1 and PDGFR signaling abolished platelet-induced MMT in MCs.

CONCLUSIONS

MCs contribute to lesional progression and fibrosis through platelet-induced MMT.

Development of novel biocompatible thermosensitive anti-adhesive agents using human-derived acellular dermal matrix

Postoperative adhesion is a natural phenomenon that occurs in damaged tissue cells. Several anti-adhesion agents are currently used, but there is no leading-edge product with excellent adhesion-preventive effects. The purpose of this study was to develop ideal anti-adhesive agents using human-derived acellular dermal matrix (ADM). We developed 5 new biocompatible thermosensitive anti-adhesion barriers (AABs) using micronized human-derived ADM, hyaluronic acid, and temperature-sensitive and biocompatible synthesized polymers. The biocompatibility, anti-adhesion effect, and biodegradability of these AABs were compared with those of commercial thermosensitive anti-adhesion agents. No cytotoxic effects were observed in vitro and in vivo. Animal testing of adhesion resistance confirmed that the adhesion area, strength, and grade of AAB03 were statistically superior to those of the control group. Factors related to adhesion formation, such as lymphocytes, macrophages, microvessels, and collagen fiber density, were observed using specific staining methods; the results confirmed that AAB03 group exhibited significantly lower macrophage counts, microvessel density, and collagen fiber density than the control groups. Furthermore, AAB03 was completely absorbed by 6 weeks. Thus, AAB03 has the potential to be used as a high-performance anti-adhesion agent.

Prospective, Randomized, Double Blind, Multicenter Study for an Autocrosslinked Polysaccharide Gel to Evaluate Antiadhesive Effect and Safety Compared to Poloxamer/Sodium Alginate After Thyroidectomy

The aim of the study was to compare the efficacy and safety between an autocrosslinked polysaccharide (ACP) gel (Hyalobarrier) and a poloxamer/sodium alginate (P/SA: Guardix-SG) in preventing adhesions after thyroidectomy and demonstrate the noninferiority of ACP gel to P/SA. To identify differences of antiadhesive efficacy and safety between the ACP gel and P/SA, we investigated various variables such as the proportion of normal esophageal motility as assessed using marshmallow esophagography, swallowing impairment, adhesion severity and so on. This prospective, randomized, double-blinded, multicenter, phase III study investigated the antiadhesive efficacy and safety of ACP gel compared with those of P/SA for 12 weeks. Subjects were randomly assigned to receive either ACP gel (n = 97) or P/SA (n = 96). The primary endpoint was the proportion of normal esophageal motility as assessed using marshmallow esophagography, while the secondary endpoints included swallowing impairment, adhesion severity, laryngoscopic assessment of the vocal cords, and voice range profile. Safety endpoints included adverse events. There was no significant difference between the ACP gel and P/SA groups in the proportion of normal esophageal motility as the primary endpoint (P = 0.7428). In addition, there were no differences in the secondary or safety endpoints between the 2 groups. It was demonstrated that ACP gel was not inferior to P/SA. ACP gel appears both effective and safe for use in preventing adhesions after thyroidectomy.

The occurrence and severity of intra-abdominal adhesions in cases of pregnancies complicated by placenta accreta: A case control study

OBJECTIVE

To examine the occurrence of intra-abdominal adhesions (IAA) among women with placenta accreta (PA).

STUDY DESIGN

Case control study conducted at a single teaching hospital on data from January 2004 to December 2016. The cases included women who underwent a cesarean hysterectomy due to PA and had a pathological confirmation of accretion. The controls were matched for delivery date and number of cesarean deliveries (CDs) at a ratio of 1:4. IAA were categorized as "none", "filmy", or "dense". The outcome measures were rate of IAA. In order to detect a 25% difference in overall IAA between the groups, with alpha of 0.05 and 80% power, a sample size of 165 women was needed.

RESULTS

Overall, 165 women (33 and 132 in the case and control groups, respectively) were included. Except for maternal age, there were no statistically significant differences between the groups in demographic and obstetric variables. Overall IAA rate was 30.3% and 47.7% in the case and control groups, respectively (RR: 0.64; 95% CI: 0.37-1.10, p = 0.04). Rate of dense adhesions was 15.2% and 32.6% in the case and control groups, respectively (RR: 0.47, 95% CI: 0.20-1.08; p = 0.03). After adjustment for maternal age, there was a significantly lower rate of overall IAA (RR = 0.39; 95% CI: 0.17-0.93; p = 0.02) and dense adhesions (RR = 0.30; 95% CI: 0.11-0.87; p = 0.02) among the cases.

CONCLUSION

The incidence and severity of IAA following CDs are low, among women who develop PA.

State of the Art on Autologous Mesothelial Transplant in Animals and Humans

Sixteen years ago rabbit and human mesothelial cells were successsfully cultured and autoimplanted. The aim of the study was merely to demostrate that mesothelial implant was possible and interesting not only in peritoneal dialysis, but also in the vaster field of medicine and surgery concerning all the mesothelial districts of the body.

The aim of this paper is to recollect the steps which have led to autolougous mesothelial transplantation and verify if the tecnique has been validated and adopted by others.

Review of the literature published in the last 15 years shows that intraperitoneal transplantation of mesothelial cells has been effective in reducing the formation of peritoneal adhesions, and in remodeling the area of mesothelial denudation. New studies on the mesothelial cell opened the way to costruction of transplantable tissue-engineered artificial peritoneum, to the utilization of mesothelial progenitor cells and to find simple metods to collect autologous mesothelial cells.

Finally mesothelial trasnsplantation may represent a new neovascular therapy in the prevention and treatment of ischemic coronaric heart disease.

Stem Cells for Mesothelial Repair: An Understudied Modality

Adhesions are bands of fibrous tissue that form between opposing organs and the peritoneum, restricting vital intrapleural and abdominal movement. They remain a major problem in abdominal surgery, occurring in more than three fourths of patients following laparotomy. Adhesions result when injury to the mesothelium is not repaired by mesothelial cells and can be viewed as scar tissue formation. The mechanism of mesothelial healing suggested the involvement of stem cells in the process. It has long been known that peritoneal wounds heal in the same amount of time regardless of size. Therefore, the mesothelium could not regenerate solely by proliferation and centripetal migration of cells at the wound edge as occurs in the healing of skin epithelium. Several studies suggest the presence of i) mesothelial stem cells that can differentiate into mesothelial cells and a few other phenotypes and/or ii) that mesothelial cells are themselves stem cells. Other studies have suggested that adult stem cells in the muscle underlying the peritoneum can differentiate into mesothelial cells and contribute to healing. Prevention of abdominal adhesions have been accomplished by delivery of autologous mesothelial cells and multipotent adult stem cells isolated from skeletal muscle. Adult stem cells from sources other than the serosal tissue offer an alternative treatment modality to prevent the formation of abdominal adhesions.

The Potential of Mesothelial Cells in Tissue Engineering and Regenerative Medicine Applications

Injury to the serosa through injurious agents such as radiation, surgery, infection and disease results in the loss of the protective surface mesothelium and often leads to fibrous adhesion formation. Mechanisms that increase the rate of mesothialisation are therefore actively being investigated in order to reduce the formation of adhesions. These include intraperitoneal delivery of cultured mesothelial cells as well as administration of factors that are known to increase mesothelial proliferation and migration. An exciting alternative that has only recently received attention, is the possible role of mesothelial progenitor cells in the repair and regeneration of denuded serosal areas. Accumulating evidence suggests that such a population exists and under certain conditions is able to form a number of defined cell types indicating a degree of plasticity. Such properties may explain the extensive use of mesothelial cells in various tissue engineering applications including the development of vascular conduits and peripheral nerve replacements. It is likely that with the rapid explosion in the fields of tissue engineering and regenerative medicine, a greater understanding of the potential of mesothelial progenitor cells to repair, replace and possibly regenerate damaged or defective tissue will be uncovered.

Efficacy of simvastatin in reducing postoperative adhesions after thyroidectomy: an experimental study

BACKGROUND

We aimed to investigate whether simvastatin had any impact on the prevention of adhesion formation after thyroidectomy in a rat model.

METHODS

This study was performed in 66 Wistar albino rats randomized into three experimental groups. A right hemithyroidectomy was carried out in all the rats. Simvastatin was administered locally at a dose of 0.5 mg/kg and 0.8 mg/kg. Control rats received a saline solution only. Changes during the 1st week, 1st month and 3rd month were evaluated. Efficacy of the treatment was assessed by using a scoring system.

RESULTS

The severity of adhesions in low-dose simvastatin group was significantly less than the control and high-dose groups during the 1st and 3rd month (p < .05). In addition, adhesions were less in the high dose group during the 3rd month, when compared to the control group (p < .05). Moreover, fibrosis and fibroblast scores, which represent adhesions, were significantly lower in low-dose and high-dose groups at 3rd month, compared to controls (p < .05).

CONCLUSIONS

We investigated the influence of simvastatin application on post-thyroidectomy adhesion formation in rats. Whether adhesions, causing technical difficulties during neck redo surgery, can be reduced by the use of simvastatin in human, needs to be studied.

Creation of Abdominal Adhesions in Mice

Abdominal adhesions consist of fibrotic tissue that forms in the peritoneal space in response to an inflammatory insult, typically surgery or intraabdominal infection. The precise mechanisms underlying adhesion formation are poorly understood. Many compounds and physical barriers have been tested for their ability to prevent adhesions after surgery with varying levels of success. The mouse and rat are important models for the study of abdominal adhesions. Several different techniques for the creation of adhesions in the mouse and rat exist in the literature. Here we describe a protocol utilizing abrasion of the cecum with sandpaper and sutures placed in the right abdominal sidewall. The mouse is anesthetized and the abdomen is prepped. A midline laparotomy is created and the cecum is identified. Sandpaper is used to gently abrade the surface of the cecum. Next, several figure-of-eight sutures are placed into the peritoneum of the right abdominal sidewall. The abdominal cavity is irrigated, a small amount of starch is applied, and the incision is closed. We have found that this technique produces the most consistent adhesions with the lowest mortality rate.

Role of the peritoneal cavity in the prevention of postoperative adhesions, pain, and fatigue

A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO₂ pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N₂O to the CO₂ pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.

Characterisation of Cultured Mesothelial Cells Derived from the Murine Adult Omentum

The human omentum has been long regarded as a healing patch, used by surgeons for its ability to immunomodulate, repair and vascularise injured tissues. A major component of the omentum are mesothelial cells, which display some of the characteristics of mesenchymal stem/stromal cells. For instance, lineage tracing studies have shown that mesothelial cells give rise to adipocytes and vascular smooth muscle cells, and human and rat mesothelial cells have been shown to differentiate into osteoblast- and adipocyte-like cells in vitro, indicating that they have considerable plasticity. However, so far, long-term cultures of mesothelial cells have not been successfully established due to early senescence. Here, we demonstrate that mesothelial cells isolated from the mouse omentum could be cultured for more than 30 passages. While epithelial markers were downregulated over passages in the mesothelial cells, their mesenchymal profile remained unchanged. Early passage mesothelial cells displayed clonogenicitiy, expressed several stem cell markers, and up to passage 5 and 13, respectively, could differentiate along the adipogenic and osteogenic lineages, demonstrating stem/progenitor characteristics and differentiation potential.

Nerve fibers and endometriotic lesions: partners in crime in inflicting pains in women with endometriosis

One of major objectives in treating endometriosis is to alleviate pain since dysmenorrhea and other types of pain top the list of complaints from women with endometriosis who seek medical attention. Indeed, endometriosis-associated pain (EAP) is the most debilitating of the disease that negatively impacts on the quality of life in affected women, contributing significantly to the burden of disease and adding to the substantial personal and societal costs. Unfortunately, the mechanisms underlying the EAP are still poorly understood. In the last two decades, one active research field in endometriosis is the investigation on the distribution and genesis of nerve fibers in eutopic and ectopic endometrium, and the attempt to use endometrial nerve fiber density for diagnostic purpose. Since EAP presumably starts with the terminal sensory nerves, in or around endometriotic lesions, that transduce noxious mediators to the central nervous system (CNS) which ultimately perceives pain, this field of research holds the promise to elucidate the molecular mechanisms underlying the EAP, thus opening new avenues for novel diagnostics and therapeutics. In this review, we shall first briefly provide some basic facts on nerve fibers, and then provide an overview of some major findings in this filed while also note some conflicting results and expose areas in need of further research. We point out that since recently accumulated evidence suggests that endometriotic lesions are wounds undergoing repeated tissue injury and repair, the relationship between endometriotic lesions and nerve fibers is not simply unidirectional, i.e. lesions promote hyperinnervations. Rather, it is bidirectional, i.e. endometriotic lesions and nerve fibers engage active cross-talks, resulting in the development of endometriosis and pain. That is, nerve fibers and endometriotic lesions are actually partners in crime in inflicting pains in women with endometriosis, aided and abetted possibly by other culprits, some yet to be identified. We provide a list of possible perpetrators likely to be involved in this crime. Finally, we discuss possible implications when viewing the relationship from this vista.

Adhesions and Healing of Intestinal Anastomoses

Background. Postoperative adhesions are the result of aberrant peritoneal healing. As they are the leading cause of postoperative bowel obstruction, anti-adherence barriers are advocated for their prevention. This study looks into the effect of these biomaterials on the healing of intestinal anastomoses. Materials and Methods. Thirty-three New Zealand White rabbits underwent laparotomy, transection of the terminal ileum, and creation of an end-to-end anastomosis. Animals were randomized into 3 groups: the Control group (n = 11); the Icodextrin group, receiving icodextrin 4% intraperitonealy (n = 11); and the HA/CMC group, having the anastomosis wrapped with a hyaluronic acid/carboxymethylcellulose film (n = 11). All animals were sacrificed on the seventh postoperative day. Macroscopic adhesions were graded and anastomotic strength was tested by the burst pressure. Histological healing was assessed in a semiquantitative way for the presence of ulceration, reepithelization, granulation tissue, inflammation, eosinophilic infiltration, serosal inflammation, and microscopic adhesions. Univariate and multivariate analysis was used. Results are given as medians with interquartile range. Results. The median adhesion scores were the following: Control 1 (0-3), Icodextrin 0 (0-1), HA/CMC 0 (0-0), P = .017. The burst pressure did not differ between the groups; however, all except one bowel segments tested burst away from the anastomosis. The macroscopic and histological anastomotic healing was comparable in all 3 groups. A poor histological anastomotic healing score was associated with a higher adhesion grade (odds ratio = 1.92; 95% confidence interval = 1.06-3.47; P = .032). Conclusion. Adhesion formation was inhibited by the materials tested without direct detrimental effects on anastomotic healing. Poor anastomotic healing provokes adhesions even in the presence of anti-adhesion barriers.

The comparison of the effects of ellagic acid and diclofenac sodium on intra-abdominal adhesion: an in vivo study in the rat model. Int Surg. 2014;99:543-550. [PMID: 25216418 DOI: 10.9738/intsurg-d-14-00065.1]

Peritoneal adhesions are seen frequently after abdominal surgery and can cause serious complications. We aimed to evaluate the effects of the oral use of diclofenac sodium and ellagic acid on formation of postoperative adhesions in rats Studies have shown that agents with anti-inflammatory properties and antioxidant substances can prevent adhesion by decreasing oxidative stress. We compared and evaluated the effects of ellagic acid that has strong antioxidant and anti-inflammatory properties and the nonsteroidal anti-inflammatory diclofenac sodium on peritoneal adhesion development in our experimental study. Laparotomy was performed with a midline incision under general anesthesia and an adhesion model was created on the antimesenteric side of the cecum in Groups I, II, and III. Group I received 85 mg/kg ellagic acid and Group II, 50 mg/kg diclofenac sodium through the nasogastric catheter while Group III received no medication. Only laparotomy was performed in Group IV. The rats were sacrificed at the end of the 14th day. Following macroscopic scoring, tissue samples were removed and subjected to biochemical and histopathologic evaluation. The degree of adhesion and the malondialdehyde level were decreased (P < 0.05), and glutathione level increased (P < 0.05) in Group I compared to Group II and Group III. The effects of ellagic acid on the prevention of peritoneal adhesion were found to be stronger than diclofenac sodium. This can be explained by the fact that ellagic acid is a strong antioxidant and decreases oxidative stress with anti-inflammatory and anti-angiogenic effects.

Adhesions are the major cause of complications in operative gynecology

Adhesion formation has been found to be highly prevalent in patients with a history of operations or inflammatory peritoneal processes. These patients are at a high risk of serious intraoperative complications during a subsequent operation if adhesiolysis is performed. These complications include bowel perforation, ureteral or bladder injury, and vascular injury. In order to minimize the risk of these complications, adhesiolysis should only be performed by experienced surgeons, and intraoperative strategies must be adopted. The reduction of the overall incidence of adhesions is essential for subsequent surgical treatments. Anti-adhesion strategies must be adopted for preventing the reoccurrence of adhesions after abdominopelvic operations. The strategies employed to reduce the risk and the overall incidence of adhesions have been elucidated in this article.

Pycnogenol prevents peritoneal adhesions

PURPOSE

This study tested the ability of pycnogenol, an extract from the bark of the French maritime pine (Pinus pinaster), to prevent intra-abdominal adhesions.

METHODS

Thirty female Wistar albino rats were separated randomly into three equal groups: Group (1) the control group, which underwent surgery, but was given no drug; Group (2) given 10 mg/kg of pycnogenol dissolved in normal saline intraperitoneally for 10 days after surgery; and Group (3) given 0.1 mL of normal saline for 10 days intraperitoneally after surgery. On post-operative day 10, all of the animals were killed and any adhesions were evaluated macroscopically and histopathologically.

RESULTS

The macroscopic adhesion scores (mean ± SD) for Groups 1, 2, and 3 were 2.5 ± 0.53, 0.60 ± 0.70, and 2.0 ± 0.82, respectively. The macroscopic adhesion score was significantly lower in Group 2 than in Groups 1 and 3 (p < 0.001). All three components of the histopathological evaluation (inflammation, fibrosis, and neovascularization) were significantly lower in Group 2 than in Groups 1 or 3 (p < 0.001, p < 0.001, and p = 0.004, respectively).

CONCLUSIONS

Pycnogenol was found to be effective at preventing surgery-related adhesions in an animal model.

Computed tomography and magnetic resonance imaging in the evaluation of pelvic peritoneal adhesions: What radiologists need to know?

Pelvic peritoneal adhesions constitute an important cause of concern which affects the life of millions of people worldwide due to complications like abdominal pain, bowel obstruction and infertility along with challenges in surgical exploration. Precise pre-operative diagnosis of the presence and extent of peritoneal adhesions is of great clinical and surgical importance. Diagnostic laparoscopy to detect peritoneal adhesions may itself lead to formation of adhesions. Routine CT and MRI studies are therefore useful non-invasive modalities to achieve this objective. This review article provides a brief background about the causation and patho-physiology of peritoneal adhesions. The article also addresses the range of clinical presentations in these patients, mainly from the gynecologic perspective. This article provides an illustrative review of CT and MRI findings with laparoscopic correlation. A new ‘imaging-based grading system’ for pre-operative quantification of the burden of peritoneal adhesions is also proposed. Despite practical challenges in accurate pre-operative diagnosis of peritoneal adhesions on imaging, detection of peritoneal adhesions is certainly feasible on routine CT and MRI scans and should be an integral part of image interpretation.

Efficacy of glycerol and flax seed oil as anti-adhesive barriers after thyroidectomy

Background

We evaluated the effects of local flax seed oil and glycerol application for reducing adhesion formation after thyroidectomy.

Material/Method

We randomly assigned 18 female Wistar albino rats (median weight: 275 g, median age: 4.5 mth) to 3 groups: 0.1 ml 0.9% NaCl, glycerol, and flax seed oil were sprayed in a perithyroidal area after thyroidectomy operation on all animals as anti-adhesive barriers. Rats were sacrificed on the postoperative 14^th day and adhesions were evaluated macroscopically and microscopically.

Results

The median macroscopic adhesion score was 3.0±0.0 in the 0.9% NaCl group, 1.33±0.52 in the glycerol group, and 1.67±0.53 in the flax seed oil group. The median histopathological fibrosis scores were 2.33±0.82, 0.67±0.52, and 0.83±0.75, respectively. Both glycerol and flaxseed oil group macroscopic and microscopic scores were significantly lower than the 0.9% NaCl group (p<0.05). There was no significant difference among the groups (p>0.05).

Conclusions

Glycerol and flax seed oil both decrease the incidence of post-thyroidectomy adhesion in rats, but glycerol is more effective.

Autotaxin signaling governs phenotypic heterogeneity in visceral and parietal mesothelia

Mesothelia, which cover all coelomic organs and body cavities in vertebrates, perform diverse functions in embryonic and adult life. Yet, mesothelia are traditionally viewed as simple, uniform epithelia. Here we demonstrate distinct differences between visceral and parietal mesothelia, the most basic subdivision of this tissue type, in terms of gene expression, adhesion, migration, and invasion. Gene profiling determined that autotaxin, a secreted lysophospholipase D originally discovered as a tumor cell-motility-stimulating factor, was expressed exclusively in the more motile and invasive visceral mesothelia and at abnormally high levels in mesotheliomas. Gain and loss of function studies demonstrate that autotaxin signaling is indeed a critical factor responsible for phenotypic differences within mesothelia. Furthermore, we demonstrate that known and novel small molecule inhibitors of the autotaxin signaling pathway dramatically blunt migratory and invasive behaviors of aggressive mesotheliomas. Taken together, this study reveals distinct phenotypes within the mesothelial cell lineage, demonstrates that differential autotaxin expression is the molecular underpinning for these differences, and provides a novel target and lead compounds to intervene in invasive mesotheliomas.

Adhesions after abdominal surgery: a systematic review of the incidence, distribution and severity. Surg Today. 2014;44:405-420. [PMID: 23657643 DOI: 10.1007/s00595-013-0591-8]

Abdominal adhesions are associated with increased postoperative complications, cost and workload. We performed a systematic review with statistical pooling to estimate the formation rate, distribution and severity of postoperative adhesions in patients undergoing abdominal surgery. A literature search was carried out for all articles reporting on the incidence, distribution and severity of adhesions between January 1990 and July 2011. Twenty-five articles fulfilled the inclusion criteria. The weighted mean formation rate of adhesions after abdominal surgery was 54 % (95 % confidence interval [CI] 40-68 %), and was 66 % (95 % CI 38-94 %) after gastrointestinal surgery, 51 % (95 % CI 40-63 %) after obstetric and gynaecological surgery and 22 % (95 % CI 7-38 %) after urological surgery. The mean overall severity score was 1.11 ± 0.98 according to the Operative Laparoscopy Study Group classification. Laparoscopic surgery reduced the adhesion formation rate by 25 % and decreased the adhesion severity score (laparoscopic; 0.36 ± 0.69 vs. open; 2.14 ± 0.84) for gastrointestinal surgery. Our results demonstrate that the incidence and severity of abdominal adhesions varies between surgical specialties and procedures. An increased awareness of adhesions can help in identifying the underlying mechanisms of adhesion formation and novel therapeutic approaches, while also improving the surgical consent process.

Manual Physical Therapy for Non-Surgical Treatment of Adhesion-Related Small Bowel Obstructions: Two Case Reports. J Clin Med. 2013;2:1-12. [PMID: 26237678 PMCID: PMC4470113 DOI: 10.3390/jcm2010001]

Background: Adhesion formation is a widely acknowledged risk following abdominal or pelvic surgery. Adhesions in the abdomen or pelvis can cause or contribute to partial or total small bowel obstruction (SBO). These adhesions deter or prevent the passage of nutrients through the digestive tract, and may bind the bowel to the peritoneum, or other organs. Small bowel obstructions can quickly become life-threatening, requiring immediate surgery to resect the bowel, or lyse any adhesions the surgeon can safely access. Bowel repair is an invasive surgery, with risks including bowel rupture, infection, and peritonitis. An additional risk includes the formation of new adhesions during the healing process, creating the potential for subsequent adhesiolysis or SBO surgeries. Objective: Report the use of manual soft tissue physical therapy for the reversal of adhesion-related partial SBOs, and create an initial inquiry into the possibility of nonsurgical lysis of adhesions. Case Reports: Two patients presenting with SBO symptoms due to abdominal adhesions secondary to abdominal and pelvic surgery were treated with manual soft tissue physical therapy focused on decreasing adhesions. Conclusions: Successful treatment with resolution of symptom presentation of partial SBO and sustained results were observed in both patients treated.

Thymosin β4 mobilizes mesothelial cells for blood vessel repair

Mesothelium is the simple squamous epithelium covering all abdominal organs and the coeloms in which those organs reside. While the structural characteristics of this cell type were documented a century ago, its potential in development, disease, and wound healing is only now becoming apparent. In the embryo, mesothelia provide vasculogenic cells for the developing heart, lungs, and gut. Furthermore, adult mesothelial cells can be reactivated using thymosin β4 and mobilized to aid in tissue repair. Despite their positive role in development and repair, mesothelia are also susceptible to adhesion and tumor formation. With knowledge that the mesothelium is an important mediator of tissue repair as well as disease, it will be important to identify other factors like thymosin β4 that have the ability to potentiate these cells. Future use of chemical and genetic agents in conjunction with mesothelial cells will lead to enhanced therapeutic potential and mitigation of deleterious outcomes.

Is Patient Education About Adhesions a Requirement in Abdominopelvic Surgery?

Background: Over the past decades, our knowledge and understanding of adhesions and adhesion-related complications has increasingly grown and it has become evident that adhesions have significant implications for patients, physicians and the healthcare system. The question arises whether this has resulted in greater awareness of adhesion-related problems among practicing physicians and appropriate patient education on this topic in daily practice. The following article provides a brief overview of the important subject of adhesions, discusses current awareness of adhesions among patients and doctors and addresses the consequences of failure to provide patient education and consent from a medical perspective. Methods: Selective literature searches were conducted in PubMed and the Cochrane Library. A patient information and consent form was developed based on several years' experience and expertise in the field of adhesions. Results: Adhesions are the most common type of complication in abdominopelvic surgery today, with devastating consequences for some patients. Surveys investigating the awareness of adhesions among physicians and patients clearly showed that even well-informed physicians fail to educate their patients adequately. Such failure could potentially lead to successful medical malpractice lawsuits against doctors. Conclusion: Considering their clear clinical impact, adhesions and related consequences should always be discussed with patients preoperatively. A newly developed consent form that specifically addresses adhesion formation may serve to thoroughly educate patients preoperatively and to adequately document the process of doing so.

Intra-abdominal adhesions: cellular mechanisms and strategies for prevention

Postoperative intra-abdominal adhesions represent a serious clinical problem. In this review, we have focused on recent progress in the cellular and humoral mechanisms underpinning adhesion formation, and have reviewed strategies that interfere with these pathways as a means to prevent their occurrence. Current and previous English-language literature on the pathogenesis of adhesion formation was identified. As the burden of surgical disease in the world population increases, and the frequency of reoperation increases, prevention of adhesion formation has become a pressing goal in surgical research.

Visceral mobilization can lyse and prevent peritoneal adhesions in a rat model

OBJECTIVE

Peritoneal adhesions are almost ubiquitous following surgery. Peritoneal adhesions can lead to bowel obstruction, digestive problems, infertility, and pain, resulting in many hospital readmissions. Many approaches have been used to prevent or treat adhesions, but none offer reliable results. A method that consistently prevented or treated adhesions would benefit many patients. We hypothesized that an anatomically-based visceral mobilization, designed to promote normal mobility of the abdominal contents, could manually lyse and prevent surgically-induced adhesions.

MATERIAL AND METHODS

Cecal and abdominal wall abrasion was used to induce adhesions in 3 groups of 10 rats (Control, Lysis, and Preventive). All rats were evaluated 7 days following surgery. On postoperative day 7, unsedated rats in the Lysis group were treated using visceral mobilization, consisting of digital palpation, efforts to manually lyse restrictions, and mobilization of their abdominal walls and viscera. This was followed by immediate post-mortem adhesion evaluation. The rats in the Preventive group were treated daily in a similar fashion, starting the day after surgery. Adhesions in the Control rats were evaluated 7 days after surgery without any visceral mobilization.

RESULTS

The therapist could palpate adhesions between the cecum and other viscera or the abdominal wall. Adhesion severity and number of adhesions were significantly lower in the Preventive group compared to other groups. In the Lysis and Preventive groups there were clear signs of disrupted adhesions.

CONCLUSIONS

These initial observations support visceral mobilization may have a role in the prevention and treatment of post-operative adhesions.

Feasibility and safety of adhesiolysis using transgastric NOTES approach: a pilot survival study in a porcine model

OBJECTIVES

Although adhesions can be removed by adhesiolysis using laparotomy or laparoscopy, they typically recur sometimes with equal severity. It is suggested that minimizing the invasiveness of the operative technique by using natural orifice translumenal endoscopic surgery (NOTES) may reduce adhesion re-formation. The aim of the study was to evaluate the feasibility and safety of adhesiolysis by using a novel transgastric NOTES approach and collect pilot data on adhesion recurrence after transgastric NOTES adhesiolysis.

METHODS

One nonsurvival and 5 survival female pigs were used in this experimental survival study. Interventions included (a) induction of adhesions by laparotomy, (b) 2 weeks survival, (c) transgastric NOTES adhesiolysis with endoscopic evaluation and scoring of adhesions before and immediately after adhesiolysis, (d) 2 weeks survival, and (e) necropsy with endoscopic and necroscopic evaluation and scoring of recurrent adhesions. Main outcome measures were (a) survival and complication rates and (b) assessment of adhesion formation and re-formation using the Hopkins Adhesion Formation Score.

RESULTS

No mortality and no complications were observed. A total of 11 adhesions formed before the adhesiolysis in 5 survival study animals. All were successfully divided. The frequency of adhesions and median adhesion formation score decreased significantly immediately after adhesiolysis compared with that prior to the procedure (frequency, 11 vs 0, P = .011; the median score = 2.0 [range 1-3] vs 0.0 [range 0-0], P = .004). The treatment gains maintained at 2 weeks after the adhesiolysis.

LIMITATIONS

The limitations of this study were the low number of study animals and short-term follow-up data.

CONCLUSIONS

Adhesiolysis using NOTES transgastric approach is feasible, safe, and effective with minimal adhesion re-formation.

Peritoneal damage: the inflammatory response and clinical implications of the neuro-immuno-humoral axis. World J Surg. 2010;34:704-720. [PMID: 20049432 DOI: 10.1007/s00268-009-0382-y]

BACKGROUND

The peritoneum is a bilayer serous membrane that lines the abdominal cavity. We present a review of peritoneal structure and physiology, with a focus on the peritoneal inflammatory response to surgical injury and its clinical implications.

METHODS

We conducted a nonsystematic clinical review. A search of the Ovid MEDLINE database from 1950 through January 2009 was performed using the following search terms: peritoneum, adhesions, cytokine, inflammation, and surgery.

RESULTS

The peritoneum is a metabolically active organ, responding to insult through a complex array of immunologic and inflammatory cascades. This response increases with the duration and extent of injury and is central to the concept of surgical stress, manifesting via a combination of systemic effects, and local neural pathways via the neuro-immuno-humoral axis. There may be a decreased systemic inflammatory response after minimally invasive surgery; however, it is unclear whether this is due to a reduced local peritoneal reaction.

CONCLUSIONS

Interventions that dampen the peritoneal response and/or block the neuro-immuno-humoral pathway should be further investigated as possible avenues of enhancing recovery after surgery, and reducing postoperative complications.

Intra-abdominal administration of bevacizumab diminishes intra-peritoneal adhesions

AIM

To determine the effect of a single dose of bevacizumab on adhesion formation in the rat cecum abrasion model.

METHODS

The cecum and parietal peritoneum of 38 male Wistar rats were abraded to promote adhesion formation. The rats were randomized into 2 groups: group 1 received bevacizumab (2.5 mg/kg) intraperitoneally, and group 2 received saline. On day 30 animals were killed, adhesions scored, and histopathological samples taken.

RESULTS

There was no wound dehiscence; there were 2 incision hernias (5.3%), 1 per group. Thirty-seven animals developed adhesions (97.4%). Adhesion grade and severity scores were significantly different between groups 1 and 2 at 2.7:1.6 (P = .018) and 3.8:2.7 (P = .007), respectively. There was no difference in adhesion square area (27.7:25.0%; P = .16), location (P = 1.00), or number (2.1:1.3; P = .06). Histopathology confirmed the statistical difference between groups (P = .049), and a highly significant correlation between results was shown (r = .758; P = .0001).

CONCLUSION

A single dose of intraperitoneal bevacizumab significantly reduces grade and severity of abdominal adhesions in the cecum abrasion rat model.

Partial small bowel obstruction: clinical issues and recent technical advances

Mechanical small bowel obstruction (SBO) remains a common clinical problem despite ever-increasing medical and surgical advances. The predominant etiology continues to be postoperative adhesions, accounting for approximately two-thirds of all obstructive events. As opposed to high-grade or complete small bowel obstruction where the clinical and radiographic findings are typically more diagnostic and the treatment plan more defined, partial SBO represents a subgroup, where the evaluation is more arduous, the diagnosis more elusive, and the management less defined. Operative and nonoperative approaches to treatment are successful and are based on the etiology and clinical status of the patient. A paradox remains, however, treating a predominantly surgically induced condition with repeated operations. Several advances in the treatment and prevention of SBO have become practice in past decade. This article reviews the clinical issues and technical advances of this challenging condition.