Prevention of postoperative peritoneal adhesions: effects of lysozyme, polylysine and polyglutamate versus hyaluronic acid

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

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

Effects of Streptokinase and Normal Saline on the Incidence of Intra-abdominal Adhesion 1 Week and 1 Month after Laparotomy in Rats

Background:

Intra-abdominal adhesions after surgery are usually in the form of bands and can annoy the patient throughout life causing repeated surgical procedures. Therefore, any action to prevent adhesions after surgery can increase longevity and quality of life. For this aim, this study investigates the effect of streptokinase and normal saline on the 7^th day and 1 month after laparotomy.

Materials and Methods:

Experimental study was conducted on thirty healthy male Wistar rats weighing 200–250 g with age of 3 months divided into three groups of 10. Group I: No treatment, Group II: Received normal saline, and Group III: Received normal saline and streptokinase at the same time. One week and 1 month after laparotomy, the frequency of the presence or absence of adhesion bands was performed by a person who was unaware of the sample grouping. The collected information was analyzed with the SPSS software (version 16; SPSS Inc., Chicago, IL, USA).

Results:

Adhesion frequency was found to be 20% on the 7^th day (early) and 1 month after laparotomy (late) for Group 1, and it was 40% on early and late for Group II, while 0% on the early and late for Group III. Hence, in the group receiving streptokinase, no early or late adhesion was observed; therefore, it had a significant role in the prevention of intra-abdominal adhesions (P < 0.05). However, adhesions in the group receiving normal saline had no remarkable difference with the group receiving no drug (P > 0.05).

Conclusion:

According to the results of our study, we believe that streptokinase could be a good antiadhesive agent considering its effectiveness.

Prevention of pleural adhesions by bioactive polypeptides - a pilot study

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prevention of adhesion formation in Wistar-albino rats by increased bowel movements achieved with oral Ricinus oil use for 8 days postoperatively: an experimental study

OBJECTIVE

Adhesion formation frequently occurs after abdominopelvic surgery and can cause significant morbidity for patients. Meticulous hemostasis, minimal access surgery and utilization of surgical adjuvants intraoperatively are clinically useful measures to minimize adhesion formation. We investigated the clinical efficiency of oral Ricinus oil treatment for 8 days postoperatively to decrease adhesion formation in this case-control study in a rat model.

STUDY DESIGN

Following computer-generated randomization, 24 female Wistar-albino rats were operated on, with 10 standard cautery lesions on the right uterine horn and two simple suture lesions on left uterine horn generated with absorbable material. Half (n=12) the rats received 0.13 g (0.2 ml) Ricinus oil emulsion (40 g/60 ml) via the oral route during the first 8 days postoperatively, and the remaining rats (n=11) were considered as controls. The extent, severity, degree, total adhesion scores and histopathological features of the adhesions were the main outcome measures.

RESULTS

The degree and total adhesion formation scores in the Ricinus oil group and control group revealed significant differences in adhesion extent and severity. The total adhesion scores of the Ricinus oil and control groups were 3.00 ± 2.21 and 5.18 ± 2.78 respectively (P<0.05). Differences in type of inflammation, extent of inflammation and vascularization were statistically insignificant for suture and cautery lesions individually (P>0.05).

CONCLUSIONS

Ricinus oil treatment following abdominopelvic surgery for the 8-day period that covers the completion of tissue healing process may be a promising, cheap and cost-effective treatment strategy for patients.

Prevention of postoperative peritoneal adhesions

Adhesions are bands of tissue that connect organs together. It is frequently reported after surgery and remains a major problem for health and society. Efforts to prevent or reduce peritoneal adhesions mostly have been unsuccessful, hindered by their empirical basis, lack of good predictive animal models and complexity of adhesion pathogenesis. Although a good surgical technique is a crucial part of adhesion prevention, the technique alone cannot effectively eliminate the adhesions. Thus, there remains a room for further research. A comprehensive literature review of published experimental and clinical studies of adhesion prevention was carried out at the University of Bristol electronic library (MetaLib) with cross-search of seven different medical databases (AMED-Allied and Complementary Medicine Database, BIOSIS Previews on Web of Knowledge, Cochrane Library, Embase and Medline on Web of Knowledge, OvidSP and PubMed) by using key words (peritoneal adhesions, postoperative adhesions, prevention) to explore the progress in different surgical strategies and adjuvant materials used to prevent adhesions formation and reformation. By the end of the study, recommendations formulated for surgeons to be followed during the operations to prevent, as much as possible, the postoperative adhesions.

A novel polypeptide derived from human lactoferrin in sodium hyaluronate prevents postsurgical adhesion formation in the rat

OBJECTIVE

The objective of the study was to evaluate whether a peptide derived from human lactoferrin, PXL01 could act safely to reduce the formation of peritoneal adhesions in the rat model and to map the molecular mechanisms of its action.

SUMMARY BACKGROUND DATA

Adhesion formation is a significant problem within every surgical discipline causing suffering for the patients and major cost for the society. For many decades, attempts have been made to reduce postsurgical adhesions by reducing surgical trauma. It is now believed that major improvements in adhesion prevention will only be reached by developing dedicated antiscarring products, which are administrated in connection to the surgical intervention.

METHODS

Anti-inflammatory as well as fibrinolytic activities of PXL01 were studied in relevant human cell lines. Using the sidewall defect-cecum abrasion model in the rat, the adhesion prevention properties of PXL01 formulated in sodium hyaluronate were evaluated. Large bowel anastomosis healing model in the rat was applied to study if PXL01 would have any negative effects on intestine healing.

RESULTS

PXL01 exhibits an inhibitory effect on the most important hallmarks of scar formation by reducing infections, prohibiting inflammation, and promoting fibrinolysis. PXL01 formulated in sodium hyaluronate markedly reduced formation of peritoneal adhesions in rat without any adverse effects on wound healing.

CONCLUSIONS

A new class of synthetically derived water soluble low molecular weight peptide compound, PXL01 showed marked reduction of peritoneal adhesion formation in an animal model without any negative effects on healing. On the basis of these data, a comprehensive adhesion prevention regimen in clinical situation is expected.

Effect of Bioactive Polypeptides on Leaking Large Bowel Anastomosis and Intestines in the Rat

Anastomotic leakage and postoperative adhesions represent major complications after colorectal surgery. We have previously shown a positive effect on both anastomotic strength and abdominal adhesions by the use of differently charged bioactive polypeptides. The present study aimed to investigate the effect of the same polypeptides on the healing of an insufficient intestinal anastomosis, as well as on accidental intestinal injury, in addition to measuring the preventive effect against the development of abdominal adhesions. An insufficient, and thereby potentially leaking, intestinal anastomosis and punctures of the intestine ("accidental intestinal injury model") were performed in rats. The treatment groups received intraperitoneal administration of poly-L-lysine and poly-L-glutamate, while controls received sodium chloride. Burst pressure, extent of abdominal adhesions, and postoperative complications were analyzed in both experimental models. A significant decrease of adhesions was seen in all animals treated with polypeptides (p < .05). Burst pressure was significantly higher (p < .001) in animals with intestinal perforation as seen on day 1 and then decreasing. A significant decrease in the incidence of peritonitis was also noted early (day 1) in this model (p = .002). The mortality and complications were high in the intestinal anastomosis model, though not affected by treatment with polypeptides. Intraabdominal adhesions were significantly reduced using polypeptides in this study, with no observed effect on other postsurgical complications. There were signs of less infectious complications in polypeptide treated animals. In animals with accidental intestinal injury, a higher burst pressure was noted in treated animals.

Role of fibrin glue in the prevention of peritoneal adhesions in ventral hernia repair

PURPOSE

The aim of this study was to investigate the effects of fibrin glue on the prevention of postoperative peritoneal adhesion to prosthetic materials used in ventral hernia repair.

METHODS

Ten pigs were included in this study. The abdomens of the animals were opened by means of a median subumbilical laparotomy to place four prostheses that were cut into square pieces of 4 x 4 cm. The two prostheses in the most cephalic position were polypropylene meshes, and the other two prostheses in a more caudal position were expanded polytetrafluoroethylene prostheses (Dualmesh Plus Corduroy). The prostheses on the right side of each animal were previously impregnated with fibrin glue. After 5 weeks, the animals were reoperated on to assess the quantity and quality (consistency) of the adhesions.

RESULTS

There were fewer intraperitoneal adhesions and they were more labile in the case of prostheses impregnated with fibrin glue. Moreover, we also observed that in many of the animals the polypropylene mesh did not show any adhesions, although polypropylene has been considered to be a typical adhesion producing material.

CONCLUSIONS

Fibrin glue reduces both the quantity and consistency of adhesions, even in the case of polypropylene meshes.

Differently charged polypeptides in the prevention of post-surgical peritoneal adhesions

OBJECTIVE

Peritoneal adhesions develop after almost all surgical interventions in the abdomen. We have developed an efficient treatment against post-surgical adhesions consisting of a combination of positively charged poly-L-lysine and negatively charged poly-L-glutamate. The aim of the present study was to further develop the concept of applying oppositely charged polypeptides in the prevention of adhesion formation, by evaluating different doses of the peptides, alterations in the way of administration, and also testing alternative components.

MATERIAL AND METHODS

Eighty-five NMRI mice were divided into six groups. A standardized peritoneal injury model was used. The groups received physiologic sodium chlorine, poly-L-lysine+poly-L-glutamate, low molecular weight poly-L-lysine+poly-L-glutamate, locally administered poly-L-lysine+poly-L-glutamate, in vitro mixed poly-L-lysine+poly-L-glutamate and poly-L-arginine+poly-L-glutamate, respectively. After 7 days, the extent of adhesion formation was determined during relaparotomy and was expressed as the mean percentage of the total wound length.

RESULTS

A significant decrease (p <0.001) in the peritoneal adhesion rate was detected in all groups, with the exception of the group administered poly-L-arginine. Among those animals that received poly-L-lysine and poly-L-glutamate, the low dose of poly-L-lysine administration resulted in the most pronounced anti-adhesive effect.

CONCLUSIONS

The most effective polypeptide combination was poly-L-lysine and poly-L-glutamate, also showing effectiveness when used at low doses and by local application. The differences in adhesion prevention and the possible underlying mechanisms are discussed and the key role of poly-L-lysine is elucidated.

Efficacy of Bioactive Polypeptides on Bleeding and Intra-Abdominal Adhesions

BACKGROUND

Perioperative bleeding and postoperative adhesions are two problems encountered in abdominal surgery. Commercial products are available that decrease both bleeding and development of abdominal adhesions, but no products are effective in both situations. The combination of differently charged bioactive polypeptides, administered intraperitoneally, has previously been shown effective in decreasing postoperative adhesions. The present study is a pilot examination of the effects on perioperative bleeding and postoperative adhesions, applying the polypeptide concept.

METHODS

Standardized wounds in the liver and spleen were induced in 52 NMRI mice. The amounts of bleeding and postoperative adhesions were measured after 1 and 7 days, respectively. Separate animals were examined after 8 weeks for long-term healing of the parenchymal wounds.

RESULTS

Both parenchymal bleeding and the extent of adhesions significantly decreased (p = 0.001 and p = 0.029, respectively) as compared to controls. Histology after 8 weeks showed no clear signs of impaired or altered healing.

CONCLUSION

Intraperitoneal administration of differently charged polypeptides significantly decreased postoperative bleeding and postoperative adhesions. Bioactive polypeptides appear promising in the promotion of peritoneal healing and merits further studies.

Management of complications in surgery of the colon

BACKGROUND

General surgeons are frequently confronted with colorectal diseases in their daily practice, whereby colorectal cancer is the second most common malignant tumour, with almost 5000 new cases every year in Austria. The incidence of benign colon disorders requiring surgery (e.g. colon polyps, sigmoid diverticulitis) is also increasing. The first aim in colon surgery should be to avoid complications and if they occur to treat them properly.

METHODS

We basically distinguish between general and special complications. As general complications, prevention of malnutrition and support of the immune system should receive special attention. As the number of elderly patients increases, so does the risk not only of thrombembolic complications but also of critical cardiocirculatory situations, and renal and hepatic failure. Special complications depend either on the type of surgery (laparoscopic assisted, conventional open surgery) or the techniques employed (stapled, hand sutured). Handling of the tissue also plays a major role (e.g. dry versus wet pads).

RESULTS

Shortening of the postoperative stay decreases both hospital costs and the incidence of infections, meaning that minimally invasive surgery and postoperative "fast track nutrition" should be promoted. Emergency operations should be avoided (e.g. bridging through colonic stents), as morbidity and mortality are clearly increased in comparison to (semi-) elective operations. During the operation itself, new equipment and techniques (such as Ultracision®, Ligasure®) as well as a well coordinated team help to reduce complications and duration of surgery.

CONCLUSIONS

To avoid is better than to repair. If complications do occur, appropriate surgical and intensive - care measures should be taken immediately.

Novel treatment in peritoneal adhesion prevention: protection by polypeptides

OBJECTIVE

To evaluate a novel antiadhesive polypeptide complex containing a combination of poly-L-glutamate and poly-L-lysine in order to study its effectiveness and mechanisms in the prevention of postoperative abdominal adhesions in mice.

MATERIAL AND METHODS

The length of peritoneal adhesions was measured and expressed in percentage of the wound length in a standardized peritoneal injury model and evaluated 7 days and 4 weeks after adhesion induction. The test compound was administered intraperitoneally following surgery. Peritoneal swabs, including the wound area, were stained in order to determine the peritoneal location and clearance of the polypeptides. Electron microscopy was performed to analyze the wound surface and the ultra-structural changes of the phagocytes in cell culture. Moreover, flow cytometry was used to evaluate the effect on macrophage phagocytic function.

RESULTS

The poly-L-lysine and poly-L-glutamate combination significantly decreased peritoneal adhesions both at 7 days' (p < 0.001) and 4 weeks' (p < or = 0.001) follow-up. From the first day, the compound was found in the wound, after which this was gradually rebuilt, and covered with mesothelial cells. The macrophages phagocytosed the test compound particles, resulting in significant cell growth, and large phagocytic vacuoles.

CONCLUSIONS

The intraperitoneal administration of poly-L-lysine and poly-L-glutamate resulted in a significant decrease in experimental postoperative peritoneal adhesions.

Increasing anastomosis safety and preventing abdominal adhesion formation by the use of polypeptides in the rat

BACKGROUND AND AIMS

Postoperative adhesions can potentially be reduced using different anti-adhesive agents, though these drugs tend to compromise healing of an intestinal anastomosis. No method that significantly increases anastomosis safety is known at present. The aim of the study was to develop a concept of preventing postoperative adhesions using differently charged bioactive polypeptides, also considering healing and safety of an intestinal anastomosis.

METHODS

An ileocolic anastomosis was performed under both "clean" and "septic" conditions in the rat. The treatment group received intraperitoneal poly-L-lysine and poly-L-glutamate, while controls received sodium chloride. Abdominal adhesions, anastomosis leakage and burst pressure were analysed after 1, 3, 5 and 7 days in the clean anastomosis model and after 7 days in the septic model.

RESULTS

A significant decrease (p<0.01) in the amount of adhesions was seen in animals treated with polypeptides after 1, 3 and 5 days, while no difference was seen after 7 days. The anastomosis demonstrated a significantly higher burst pressure as evaluated at days 1 and 3 (p<0.05 and p<0.01, respectively) in the polypeptide-treated animals, while no difference was seen between the groups at day 5 or 7.

CONCLUSION

The use of differently charged polypeptides administered intraperitoneally after surgery resulted in a significant decrease in the extent of postoperative adhesions. Furthermore, an increase in intestinal anastomosis safety, based on improved burst pressure during the first 3 days, i.e. the critical period during the healing process, was noted. No adverse effects were seen in surgery during septic conditions.

Fluid and pharmacological agents for adhesion prevention after gynaecological surgery

BACKGROUND

Pelvic surgery is associated with high rates of both de novo adhesion formation and adhesion reformation. Since subsequent fertility is reduced with increasing severity of periadnexal adhesions, pelvic adhesions will remain a clinical problem in infertility patients. Steroids, antihistamines and heparin were amongst the first substances to be advocated for adhesion prevention. More recently icodextrin 4%, hyaluronic acid agents and SprayGel have been used. This review aims to evaluate the role of fluid and pharmacological agents in the prevention of adhesions in fertility-conserving gynaecological surgery.

OBJECTIVES

To investigate fluid and pharmacological agents for adhesion prevention when used as adjuvants during pelvic surgery.

SEARCH STRATEGY

This review has drawn on the search strategy developed for the Menstrual Disorders and Subfertility Group. The following databases were searched: the Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE.

SELECTION CRITERIA

Randomised controlled trials investigating the use of fluid and pharmacological agents to prevent adhesion formation after fertility-conserving gynaecological surgery.

DATA COLLECTION AND ANALYSIS

Data extraction and analysis was performed independently by two authors (Metwally M and Watson A). Two-by-two tables were generated for dichotomous outcomes and expressed as odds ratios (OR) with 95% confidence intervals (CI). For continuous outcomes a standardised mean difference was used.

MAIN RESULTS

There is no evidence of benefit from the use of steroids, dextran or other pharmacological agents in any of the outcomes. The use of hyaluronic acid agents may decrease adhesion formation (OR 0.31, 95% CI 0.19 to 0.51) and prevent the deterioration of pre-existing adhesions (OR 0.28 (95% CI 0.12 to 0.66). There is insufficient evidence for the use of icodextrin 4% or SprayGel as adhesion-preventing agents. None of the studied agents has been shown to improve the pregnancy rate when used as an adjunct during pelvic surgery.

AUTHORS' CONCLUSIONS

The current evidence for the use of fluid and pharmacological agents for the prevention of adhesions is limited. There is no evidence on any benefit for improving pregnancy outcomes when pharmacological and fluid agents are used as an adjunct during pelvic surgery. There is insufficient evidence for the use of the following agents: steroids, icodextrin 4%, SprayGel and dextran in improving adhesions following surgery. There is some evidence that hyaluronic acid agents may decrease the proportion of adhesions and prevent the deterioration of pre existing adhesions. However, due to the limited number of studies available, this evidence should be interpreted with caution and further studies are needed.