Function of peritoneal exudate cells after abdominal surgery

Bioglass/ceria nanoparticle hybrids for the treatment of seroma: a comparative long-term study in rats

Background: Seroma formation is a common postoperative complication. Fibrin-based glues are typically employed in an attempt to seal the cavity. Recently, the first nanoparticle (NP)-based treatment approaches have emerged. Nanoparticle dispersions can be used as tissue glues, capitalizing on a phenomenon known as 'nanobridging'. In this process, macromolecules such as proteins physically adsorb onto the NP surface, leading to macroscopic adhesion. Although significant early seroma reduction has been shown, little is known about long-term efficacy of NPs. The aim of this study was to assess the long-term effects of NPs in reducing seroma formation, and to understand their underlying mechanism. Methods: Seroma was surgically induced bilaterally in 20 Lewis rats. On postoperative day (POD) 7, seromas were aspirated on both sides. In 10 rats, one side was treated with NPs, while the contralateral side received only NP carrier solution. In the other 10 rats, one side was treated with fibrin glue, while the other was left untreated. Seroma fluid, blood and tissue samples were obtained at defined time points. Biochemical, histopathological and immunohistochemical assessments were made. Results: NP-treated sides showed no macroscopically visible seroma formation after application on POD 7, in stark contrast to the fibrin-treated sides, where 60% of the rats had seromas on POD 14, and 50% on POD 21. At the endpoint (POD 42), sides treated with nanoparticles (NPs) exhibited significant macroscopic differences compared to other groups, including the absence of a cavity, and increased fibrous adhesions. Histologically, there were more macrophage groupings and collagen type 1 (COL1) deposits in the superficial capsule on NP-treated sides. Conclusion: NPs not only significantly reduced early manifestations of seroma and demonstrated an anti-inflammatory response, but they also led to increased adhesion formation over the long term, suggesting a decreased risk of seroma recurrence. These findings highlight both the adhesive properties of NPs and their potential for clinical therapy.

The association between visceral adiposity with systemic inflammation, oxidative stress, and risk of post-surgical adhesion

Abdominal and pelvic adhesions are common post-operative complications. Despite new medical technologies, these adhesions are appearing to be unavoidable and little is known about their causation; for example, why certain patients/or tissues are more prone to adhesions. There have been no clinical studies about increasing the risk adhesions in obese patients, but there is some evidence about the molecular mechanisms involving visceral fat (VF) that may lead to profibrotic conditions. VF is an endocrine/inflammatory organ which produces many biologically active molecules such as adipokines and inflammatory cytokines. Inflammatory conditions, oxidative stress, and the expression some fibrotic molecules in the VF may induce pathological conditions in the abdominal cavity that predispose to the formation of fibrotic bands.

Are the skin scar characteristics and closure of the parietal peritoneum associated with pelvic adhesions?

Objective:

To assess whether the abdominal scar characteristics and closure of the peritoneum were associated with pelvic adhesions.

Materials and Methods:

Patients who had undergone cesarean section between December 2015 and February 2016 were assessed prospectively in terms of age, gravida, body mass index, number of living children, number of cesarean sections, time passed since the last cesarean section, closure status of the peritoneum in the last cesarean section, presence of other diseases, smoking status, location of incision in the abdomen (medial, pfannenstiel) scar dimensions (length, width), scar status with respect to skin (hypertrophic, flat, depressive), scar color [color change/no color change (hyperpigmented/hypopigmented)], adhesion of bowel-omentum-uterus, omentum-anterior abdominal wall, uterus-anterior abdominal wall, uterus-bladder, bladder-anterior abdominal wall, fixed uterus, and uterus-omentum-anterior abdominal wall in abdominal exploration.

Results:

One hundred five pregnant women who had undergone previous ceserean section surgery by the same physician, were at least in their 30th gestational week, had surgery notes about their previous operation, and had no chronic diseases were included in the study. Age, gravida, body mass index, number of children, number of cesarean sections, time passed since the previous cesarean section, closure/non-closure of peritoneum in the previous cesarean section, and smoking status had no effect on pelvic adhesions. Intraabdominal adhesion was not found to be associated with scar length [odds ratio (OR): 1.54, 95% confidence interval (CI): 1.1-2.2; p=0.02], depressive scar (OR: 9.3, 95% CI: 3.2-27.2; p<0.001), or hypopigmented scar [OR: 0.01, 95% CI: 0.003-0.11; p<0.001].

Conclusion:

Adhesions following surgical operations are of great importance due to complications for the patient, complications in relaparotomy, and high costs. Depressive and hypopigmented abdominal scars may be associated with pelvic adhesions. We believe that closure or non-closure of the parietal peritoneum is not associated with pelvic adhesions.

What is the evidence for the use of low-pressure pneumoperitoneum? A systematic review

Background

Laparoscopic surgery has several advantages when compared to open surgery, including faster postoperative recovery and lower pain scores. However, for laparoscopy, a pneumoperitoneum is required to create workspace between the abdominal wall and intraabdominal organs. Increased intraabdominal pressure may also have negative implications on cardiovascular, pulmonary, and intraabdominal organ functionings. To overcome these negative consequences, several trials have been performed comparing low- versus standard-pressure pneumoperitoneum.

Methods

A systematic review of all randomized controlled clinical trials and observational studies comparing low- versus standard-pressure pneumoperitoneum.

Results and conclusions

Quality assessment showed that the overall quality of evidence was moderate to low. Postoperative pain scores were reduced by the use of low-pressure pneumoperitoneum. With appropriate perioperative measures, the use of low-pressure pneumoperitoneum does not seem to have clinical advantages as compared to standard pressure on cardiac and pulmonary function. Although there are indications that low-pressure pneumoperitoneum is associated with less liver and kidney injury when compared to standard-pressure pneumoperitoneum, this does not seem to have clinical implications for healthy individuals. The influence of low-pressure pneumoperitoneum on adhesion formation, anastomosis healing, tumor metastasis, intraocular and intracerebral pressure, and thromboembolic complications remains uncertain, as no human clinical trials have been performed. The influence of pressure on surgical conditions and safety has not been established to date. In conclusion, the most important benefit of low-pressure pneumoperitoneum is lower postoperative pain scores, supported by a moderate quality of evidence. However, the quality of surgical conditions and safety of the use of low-pressure pneumoperitoneum need to be established, as are the values and preferences of physicians and patients regarding the potential benefits and risks. Therefore, the recommendation to use low-pressure pneumoperitoneum during laparoscopy is weak, and more studies are required.

Comprehensive analysis of chemokines and cytokines secreted in the peritoneal cavity during laparotomy

We recently found that chemokine-driven peritoneal cell aggregation is the primary mechanism of postoperative adhesion in a mouse model. To investigate this in humans, paired samples of peritoneal lavage fluid were obtained from seven patients immediately after incision (preoperative) and before closure (postoperative), and were assayed for the presence of 27 cytokines and chemokines using multiplex beads assay. As a result, IL-6 and CCL5 showed the most striking increase during operation. Recombinant CCL5 or lavage fluid induced chemotaxis of human peripheral blood mononuclear cells. We propose that CCL5 is possibly involved in the mechanism of postoperative adhesion in humans.

Knockdown of osteopontin reduces the inflammatory response and subsequent size of postsurgical adhesions in a murine model

Adhesions between organs after abdominal surgery remain a significant unresolved clinical problem, causing considerable postoperative morbidity. Osteopontin (OPN) is a cytokine up-regulated after cell injury and tissue repair. Our previous studies have shown that blocking OPN expression at sites of cutaneous wounding resulted in reduced granulation tissue and scarring. We hypothesize that it may be possible to similarly reduce inflammation-associated fibrosis that causes small-bowel adhesions after abdominal surgery. By using a mouse model, we deliver OPN antisense oligodeoxynucleotides via Pluronic gel to the surface of injured, juxtaposed small bowel and show a significant reduction of inflammatory cell influx to the developing adhesion and a dramatic reduction in the resulting adhesion size. A significant reduction in α-smooth muscle actin expression and collagen deposition within the mature adhesion is also demonstrated. We see no impact on mortality, and the healing of serosal injury to intact bowel appeared normal given the reduced inflammatory response. Our studies suggest that dampening OPN levels might be a potentially important target for anti-adhesion therapeutics.

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.

Peritoneal repairing cells: a type of bone marrow derived progenitor cells involved in mesothelial regeneration

The peritoneal mesothelium exhibits a high regenerative ability. Peritoneal regeneration is concomitant with the appearance, in the coelomic cavity, of a free-floating population of cells whose origin and functions are still under discussion. We have isolated and characterized this cell population and we have studied the process of mesothelial regeneration through flow cytometry and confocal microscopy in a murine model lethally irradiated and reconstituted with GFP-expressing bone marrow cells. In unoperated control mice, most free cells positive for mesothelin, a mesothelial marker, are green fluorescent protein (GFP). However, 24 hrs after peritoneal damage, free mesothelin⁺/ GFP⁺ cells appear in peritoneal lavages. Cultured lavage peritoneal cells show colocalization of GFP with mesothelial (mesothelin, cytokeratin) and fibroblastic markers. Immunohistochemical staining of the peritoneal wall also revealed colocalization of GFP with mesothelial markers and with procollagen-1 and smooth muscle α-actin. This was observed in the injured area as well as in the surrounding not-injured peritoneal surfaces. These cells, which we herein call peritoneal repairing cells (PRC), are very abundant 1 week after surgery covering both the damaged peritoneal wall and the surrounding uninjured area. However, they become very scarce 1 month later, when the mesothelium has completely healed. We suggest that PRC constitute a type of monocyte-derived cells, closely related with the tissue-repairing cells known as ‘fibrocytes’ and specifically involved in peritoneal reparation. Thus, our results constitute a synthesis of the different scenarios hitherto proposed about peritoneal regeneration, particularly recruitment of circulating progenitor cells and adhesion of free-floating coelomic cells.

Prevention of intra-peritoneal adhesions in gynaecological surgery: theory and evidence

Post-operative adhesions are a significant complication of all abdominal surgical procedures. The major strategies for adhesion prevention in gynaecological surgery are focused on the optimization of surgical technique and use of anti-adhesive agents, which fall into two main categories: pharmacological agents and barriers. Surgical technique that minimizes peritoneal trauma can reduce, but cannot prevent post-operative adhesion formation. Various local and systemic drugs that can alter the local inflammatory response, inhibit the coagulation cascade and promote fibrinolysis have been evaluated. Limited data support the administration of post-operative corticosteroids in addition to systemic intra-operative corticosteroids for the prevention of adhesions after gynaecological surgery. None of the remaining pharmacological agents have been found effective for the reduction of post-operative adhesions. Barriers are currently considered the most useful adjuncts, which may reduce adhesion formation. They act by separating the traumatized peritoneal surfaces during the healing period. The separation can be achieved by solid barriers or fluids. There is limited evidence from randomized clinical trials that support the beneficial effect of most of these barrier agents in the prevention of intra-peritoneal adhesions after gynaecological surgery. However, the evidence is not adequate for definite conclusions to be drawn and further research in this field is warranted.

A randomised controlled trial on melatonin and rosiglitazone for prevention of adhesion formation in a rat uterine horn model

PURPOSE

To investigate the effectiveness of melatonin and rosiglitazone in reducing postoperative adhesion formation in a rat uterine horn model.

METHODS

Thirty non-pregnant female Wistar albino rats, weighing 180-220 g, were used as a model for postoperative adhesion formation. The rats were randomised into three groups after seven standard lesions were inflicted in a 2-cm segment of each uterine horn and lower abdominal sidewall using bipolar cauterisation. The rats were treated with 10 mg/kg, intraperitoneal melatonin, and 1 mg/kg per day peroral rosiglitazone. No medication was given to the control group. As much as 20 uterine horns of 10 rats were evaluated in each group. Extent, severity, and degree of the adhesions to the uterine horns and, inflammation and fibrosis scores (histopathologically) were evaluated after 2 weeks of the treatment.

RESULTS

There was no mortality in the groups and all of the rats recovered without incident after operation. Rosiglitazone group had lower adhesion scores [median (min-max ranges)] regarding extent, severity, and degree of the adhesions [0 (0-3), 0 (0-3) and 0 (0-3), respectively], which were significantly different (P < 0.001, P < 0.05 and P < 0.01, respectively) from those of the controls [1 (0-3), 2 (0-2) and 2 (0-3), respectively]; however, there were no statistically significant differences between rosiglitazone versus melatonin groups [1 (0-4), 2 (0-3) and 1 (0-3), respectively] and melatonin versus control groups. Moreover, no significant differences were determined between groups regarding histopathologic findings.

CONCLUSION

Rosiglitazone, but not melatonin, is effective in prevention of adhesion formation in a rat uterine horn model.

Peritoneal adhesions: facing the enemy

BACKGROUND

Postsurgical adhesions severely affect the quality of life of millions of people worldwide. Numerous attempts have been made to prevent or reduce the incidence of peritoneal adhesions, but with limited success.

DATA SOURCES

An extensive Medline search, textbooks, scientific reports and scientific journals are the data sources. We also reviewed reference lists in all articles retrieved in the search as well as those of major texts regarding postsurgical intraperitoneal adhesion formation.

CONCLUSIONS

A multifactorial approach including minimizing tissue injury, prophylactic antibiotic usage to reduce infectious morbidity, and biochemical agents with or without biomechanical barriers will reduce the amount and severity of adhesions. However, further research is needed to establish the safety, effectiveness and also the cost/benefit ratio of these substances in human subjects.

Inhibition of CCL1-CCR8 interaction prevents aggregation of macrophages and development of peritoneal adhesions

Peritoneal adhesions are a significant complication of surgery and visceral inflammation; however, the mechanism has not been fully elucidated. The aim of this study was to clarify the mechanism of peritoneal adhesions by focusing on the cell trafficking and immune system in the peritoneal cavity. We investigated the specific recruitment of peritoneal macrophages (PMphi) and their expression of chemokine receptors in murine models of postoperative and postinflammatory peritoneal adhesions. PMphi aggregated at the site of injured peritoneum in these murine models of peritoneal adhesions. The chemokine receptor CCR8 was up-regulated in the aggregating PMphi when compared with naive PMphi. The up-regulation of CCR8 was also observed in PMphi, but not in bone marrow-derived Mphi, treated with inflammatory stimulants including bacterial components and cytokines. Importantly, CCL1, the ligand for CCR8, a product of both PMphi and peritoneal mesothelial cells (PMCs) following inflammatory stimulation, was a potent enhancer of CCR8 expression. Cell aggregation involving PMphi and PMCs was induced in vitro in the presence of CCL1. CCL1 also up-regulated mRNA levels of plasminogen activator inhibitor-1 in both PMphi and PMCs. CCR8 gene-deficient mice or mice treated with anti-CCL1-neutralizing Ab exhibited significantly reduced postoperational peritoneal adhesion. Our study now establishes a unique autocrine activation system in PMphi and the mechanism for recruitment of PMphi together with PMCs via CCL1/CCR8, as immune responses of peritoneal cavity, which triggers peritoneal adhesions.

The influence of reactive oxygen species on the adhesion of pancreatic carcinoma cells to the peritoneum

Postoperative peritoneal carcinomatosis is a significant clinical problem after "curative" resection of pancreatic carcinoma. Preoperative surgical trauma activates a cascade of peritoneal defense mechanisms responsible for postoperative intra-abdominal tumor recurrence. Reactive oxygen species (ROS) play a pivotal role in this postoperative inflammatory reaction. This study explores the influence of ROS on adhesion of human pancreatic carcinoma cells to human mesothelial cells. Furthermore this study explores the influence of ROS on the presentation of adhesion molecules on Panc-1 and mesothelial cells. ROS were produced using the enzymatic reaction of xanthine with xanthine oxidase (X/XO). A reproducible in vitro assay to study adhesion of human Panc-1 carcinoma tumor cells to a mesothelial cell monolayer of primary human mesothelial cells was used. Mesothelial monolayers were incubated with ROS produced prior to adhesion of the tumor cells. Incubation of the mesothelial cells with X/XO resulted in a significant increase (69.5%) in adhesion of Panc-1 in all patients. SOD/catalase, anti-oxidants, could reduce this increase by 56.7%. ROS significantly influenced the expression of the adhesion molecules ICAM-1, VCAM-1 and CD44h on mesothelial cells, but did not influence adhesion molecule expression on Panc-1. The ROS released during the post-operative inflammatory reaction may play an important role in the adhesion of pancreatic tumor cells to the mesothelium-possibly by influencing adhesion molecule expression on mesothelial cells. Therefore ROS can partly be responsible for the enhanced post-operative intra-abdominal tumor recurrence.

The Role of Simvastatin on Postoperative Peritoneal Adhesion Formation in an Animal Model

AIM

The aim of this study is to show the effect of simvastatin on intra-abdominal adhesion formation.

METHOD

Adhesion formation was achieved by scratching the cecum and anterior abdominal wall following median laparotomy. Three different groups of 10 rats each were formed. In group I, 0.57 mg/kg/day simvastatin was injected intraperitoneally right after the operation and for 5 days thereafter. In group II, an equal dose of simvastatin to that used in group I was given via gavage. A physiological saline solution was given to group III for the same period of time. On the 6th and 14th day, blood samples were taken and peritoneal lavage was performed to measure the tissue-type plasminogen activator (t-PA) activity. Adhesions were graded via re-laparotomies on the 14th day after the first operation.

RESULTS

The adhesion scores were 1.40 +/- 0.22, 1.50 +/- 0.26, and 2.90 +/- 0.34 in groups I, II, and III, respectively (p = 0.007), and the score was higher in group III than in the other groups (p = 0.005, p = 0.011).

CONCLUSION

Intraperitoneal simvastatin application decreases adhesion formation by increasing the t-PA level in abdominal surgery.

The effect of rosiglitazone in the prevention of intra-abdominal adhesion formation in a rat uterine horn model

BACKGROUND

Effects of rosiglitazone in the prevention of adhesion formation were evaluated.

METHODS

Eighty Wistar albino rats were randomly grouped into eight equally sized groups. A 2-cm segment of the antimesenteric surface of the right uterine horn was traumatized to form a standardized lesion, using bipolar cautery. A dose-response study was performed with 0.1, 0.3, 1 and 3 mg/kg/day rosiglitazone. Fifteen days later, adhesions were evaluated clinically and histopathologically. A time-response study was performed with 1 mg/kg/day rosiglitazone (the minimum dose found to significantly affect adhesion formation). Rosiglitazone was given for 7 days post-operatively and results were compared with those of control and the 15-day group (time-response). In all these studies, rosiglitazone was orally administered 3 days before the operation and continued post-operatively. In two further experimental groups, rosiglitazone was only administered pre-operatively or post-operatively.

RESULTS

Approximately 1 mg/kg/day rosiglitazone was found to reduce adhesion scores both clinically and histopathologically. Duration of treatment was also found to affect the extent of adhesion formation. However, giving rosiglitazone either just pre-operatively or post-operatively did not significantly reduce adhesion formation.

CONCLUSION

Rosiglitazone with peroxisome proliferator-activated receptor (PPAR)-gamma agonist activity reduced the formation of i.p. adhesion possibly by reducing the initial inflammatory response and the subsequent exudation in this study.

Diphenhydramine and hyaluronic acid derivatives reduce adnexal adhesions and prevent tubal obstructions in rats

OBJECTIVE

The purpose of this study is to investigate the effects of diphenhydramine-HCl and Na-hyaluronate derivatives on the development of postoperative peritoneal adhesion and tubal obstruction.

STUDY DESIGN

Forty female rats of Sprague-Dawley type were used in the study. The rats were divided into four groups, each comprising 10 subjects. After all the rats were anaesthetized with 50mg/kg ketamine HCl, their abdomens were opened with a lower midline incision. Injury was induced on the right pelvic peritoneum and on the peritoneal surface of left uterine tube. No additional procedure was applied to the first group. 10 mg/kg diphenhydramine-HCl was given to the second group intravenously. In the third group, 0.25 mg/kg Orthovisc, a Na-hyaluronate derivative was diluted with 2 ml physiological saline and poured into the abdomen. For the fourth group, Seprafilm, a Na-hyaluronate derivative was covered in a layer of 0.7 cm x 3 cm over the left uterine tube. After 14 days, the rats were anaesthetized with ketamine HCl again, and 5 cm(3) blood sample was taken with cardiac puncture. The abdomen was opened with an incision transverse to the upper end of the midline incision, and the presence of adhesions was investigated. Detected adhesions were staged according to the Mazuji classification. Tubal patencies were inspected by injecting methylene blue from the uterine corpus into the lumen using an injector. A piece of abdominal wall of 4 cm x 4 cm was removed by extending the incision in the reverse U shape. The tensile strength and bursting pressure of the suture line were determined using the Peacock method. One gram of tissue was taken from the incision line, and hydroxyproline levels were determined by the Bergman-Loxley method. Aspartate aminotransferase (AST) levels were measured.

RESULTS

All of the rats completed the study. AST levels, tissue hydroxyproline levels and tensile strength and bursting pressure test results were found to be similar in all groups. While adhesion rates in the groups were 100, 40, 40 and 30%, respectively, adhesion stages were found to be, respectively as 2.1+/-1.7, 0.6+/-0.67, 0.6+/-0.67 and 0.5+/-0.85. Adhesion stages in the study groups were significantly lower (P<0.05). Tubal obstruction rates were found to be 70, 30, 30 and 20%, respectively.

CONCLUSION

Diphenhydramine, Orthovisc and Seprafilm significantly reduce postoperative peritoneal adhesion development, and they allow the uterine tubes to remain open.

CD4+ T cells regulate surgical and postinfectious adhesion formation

The development of adhesions in the peritoneal and pelvic cavities, which commonly form after surgery or infection, cause significant morbidity and mortality. However, the pathogenesis of adhesion formation is still poorly understood. Because T cells are important in orchestrating fibrinogenic tissue disorders, we hypothesized that they play a critical role in the pathogenesis of peritoneal adhesion formation. Using a cecal abrasion surgical model in rodents, T cell depletion and adoptive transfer experiments demonstrated that this host response is dependent on CD4+ alphabeta T cells. These cells were also critical to adhesion formation associated with experimental intraabdominal sepsis. T cell transfer studies with mice deficient in signal transducer and activator of transcription (Stat)4 and Stat6 revealed that adhesion formation was dependent on a T helper 1 response. Activated T cells homed to the peritoneal cavity 6 hours after cecal abrasion surgery and predominated at this site during adhesiogenesis. Increased levels of the T cell-derived proinflammatory cytokine interleukin (IL)-17 and of neutrophil chemoattractant CXC chemokines macrophage inflammatory protein-2/CXCL8 and cytokine-induced neutrophil chemoattractant/CXCL1 were associated with adhesion formation. The production of these chemokines was dependent on T cells. Furthermore, the administration of neutralizing antibodies specific for IL-17 or the receptor that binds these CXC chemokines, CXC chemokine receptor 2, significantly reduced the degree of adhesion formation. These results demonstrate for the first time that the immunopathogenesis of adhesion formation is under the control of T cells and that T cell-derived cytokines and chemokines play important roles in the development of this deleterious host response.

An in vivo evaluation of a chondroitin sulfate solution to prevent postoperative intraperitoneal adhesion formation

PURPOSE

The goal of this study was to determine the efficacy of a single intraperitoneal administration of a chondroitin sulfate solution in preventing postoperative adhesion formation. METHODS. Twenty-five Sprague-Dawley rats had a 1-cm(2) area of cecal serosa abraded. Controls (CON, n = 5) received no treatment, the chondroitin sulfate group (CS, n = 10) received chondroitin sulfate (0.013 g/kg) in 0.9% NaCl intraperitoneally (ip), and vehicle controls (VC, n = 10) received an equal volume of 0.9% NaCl solution ip before the abdomen was closed. All animals were sacrificed on postoperative day 10. The extent of adhesion was quantified according to Mazuji's adhesion grade (0 to 4: 0 = no adhesion and 4 = very dense adhesion) and quantitated after H&E, trichome, and immunohistochemical staining for fibrin and collagen type I and type III using digital image analysis.

RESULTS

The mean Mazuji's adhesion grade in the CON was 4.0 +/- 0.0, in the VC 2.60 +/- 0.37, and in the CS 1.3 +/- 0.42 (P < 0.01 for CS vs CON and P < 0.05 for CS vs VC comparisons). The mean gray-scale intensity (0-255: 0 = dense amount and 255 = none) of adhesion density in the CON was 105. 5 +/- 5.5, in the VC 125 +/- 15.0, and in the CS 178.3 +/- 21.0 (P < 0.01 for CS vs CON and P < 0.05 for CS vs VC comparisons). The mean adjusted intensity stain indices (AISI) for fibrin and collagen type I in the CON were 59 +/- 17 and 53 +/- 19, in the VC 27 +/- 3 and 25 +/- 7, and in the CS 16 +/- 5 and 6 +/- 3, respectively (P < 0.05 between CS and CON comparisons). The AISI of collagen type III was not significant among all the groups (P > 0.1).

CONCLUSIONS

The extent of early postoperative intra-abdominal adhesion formation as determined by gross assessment and from quantitation of fibrin and collagen type I deposition was significantly reduced by a single intraperitoneal administration of a chondroitin sulfate solution.

Prevention of postsurgical adhesions with N,O-carboxymethyl chitosan: examination of the most efficacious preparation and the effect of N,O-carboxymethyl chitosan on postsurgical healing

BACKGROUND

Adhesion formation after operation can result in major complications. We have previously demonstrated that N,O-carboxymethyl chitosan (NOCC) is an effective inhibitor of postsurgical peritoneal adhesion formation. However, the optimal form of NOCC (i.e., cross-linked gel versus solution), as well as the best time of administration for optimal reduction in adhesion development, was not investigated. In addition, because adhesion formation and normal wound healing are related events and weakening of wound healing would be a serious drawback to the use of NOCC clinically, we wished to assess the effect of NOCC on the healing of surgical incisions.

METHODS

Three surgical models were used: (1) an abdominal aortic anastomosis, (2) a large bowel anastomosis, and (3) an abdominal skin incision. In the first model Sprague-Dawley rats received an abdominal aortic transection and repair. NOCC solution or gel was administered at different time points throughout the procedure. Control and NOCC-treated animals were killed 14 days after operation. The condition of the anastomosed vessel was examined, and adhesion frequency and intensity in the abdomen were scored. In the second model Sprague-Dawley rats underwent large bowel transection and repair. Control and NOCC-treated animals were killed on postoperative days 4, 7, and 14, and strength of repair was assessed by removal of the large bowel and measurement of the bursting strength of the repaired incision. In the third model rats received an abdominal incision and were immediately closed. Control and NOCC-treated animals were killed 14 days after operation, and the skin tensile strength of the wound was measured with a tensiometer.

RESULTS

In all three models studied, NOCC treatment did not adversely affect the strength of the repaired incision. NOCC solution administered before operation did not greatly reduce adhesion formation, whereas the delivery of both NOCC gel and solution after operation was most efficacious.

CONCLUSIONS

The administration of both NOCC gel and solution after operation is most efficacious, and NOCC does not compromise postsurgical healing in rats at doses that prevent peritoneal adhesion formation.

Prevention of experimental postoperative peritoneal adhesions by N,O-carboxymethyl chitosan

BACKGROUND

Postsurgical adhesion formation can result in significant morbidity and, to a lesser extent, death. The purpose of this experiment was to assess the ability of N,O-carboxymethyl chitosan (NOCC) to prevent postsurgical adhesion formation in vivo.

METHODS

Randomized groups of Sprague-Dawley rats were studied under two abdominal surgery models, the uterine horn model and the small bowel laceration model, for the ability of NOCC to reduce the incidence and severity of adhesion formation. Adhesions in animals were assessed after death by a blinded observer 10 to 14 days after surgical manipulation.

RESULTS

NOCC consistently reduced the size, strength, and number of adhesions in both rat models. NOCC was also found to be more effective than hyaluronic acid at inhibiting adhesion formation.

CONCLUSIONS

NOCC is a more effective antiadhesion agent than is the more expensive hyaluronic acid. Although the exact mechanism of NOCC's antiadhesion activity is as yet unclear, the novel chemical is of particular interest for clinical use.

Contemporary adhesion prevention

OBJECTIVE

To (1) review the events leading to peritoneal adhesion formation; (2) review traditional adhesion prevention adjuvants; (3) overview studies for adhesion prevention barriers including a perspective for their use; and (4) look toward the future of adhesion prevention.

RESULTS

A great deal of effort has been dedicated to reduce adhesion formation because of the morbidity associated with adhesions and the associated economic burden, which considering only hospital costs and surgeons' fees, was $1,180 million in the United States. To understand the role of adhesion barriers in gynecological surgery, an appreciation of the cellular cascade and temporal nature of peritoneal repair is necessary. Evidence indicates that areas denuded of peritoneum will heal satisfactorily and that suturing of the peritoneum may increase adhesion formation. Physical barriers, including both mechanical and viscous solutions, are widely used to prevent adhesion formation by limiting tissue apposition during the critical stages of mesothelial repair. Clinical studies do not support the use of intraperitoneal, dextran for adhesion prevention. Theoretical considerations of peritoneal fluid dynamics indicate that crystalloid instillates should not prevent adhesion formation because of their short intraperitoneal residence. This prediction is consistent with clinical observation. The availability of Interceed (Johnson and Johnson Medical, Inc., Arlington, TX) and Gore-Tex Surgical Membrane (W.L. Gore, Flagstaff, Arizona) barriers provides substantial progress in postsurgical adhesion prevention.

CONCLUSIONS

Although many investigators are incorporating adhesion prevention barriers into their routine clinical situations, physician acceptance is constrained by technical difficulties.