Use of methylene blue and N,O-carboxymethylchitosan to prevent postoperative adhesions in a rat uterine horn model

Effect of methylene blue on experimental postoperative adhesion: A systematic review and meta-analysis

Adhesion is a primary challenge following surgery, and the anti-adhesive effect of methylene blue (MB) has been investigated. This systematic review and meta-analysis aimed to evaluate the effect of MB on postoperative adhesions in experimental studies. We initially searched OVID-MEDLINE, EMBASE, and Google Scholar in February 2021, and then in May 2021. The anti-adhesive efficacy of MB was compared with that of the control (either placebo or nothing) after the surgical procedure. The primary and secondary outcomes were the macroscopic and microscopic adhesion scores, respectively. Traditional meta-analysis, meta-regression, and trial sequential analysis (TSA) were performed to analyze the retrieved outcomes. We included 13 experimental studies of 367 rats (200 rats received MB and 167 rats received placebo or nothing). The macroscopic adhesion scores were significantly lower in the MB-administered group than in the control group (standardized mean difference, 2.313; 95% confidence interval, 1.104 to3.523; I² = 94.0%, Tau = 2.059). Meta-regression analysis showed that macroscopic adhesion tended to decrease with an increase in MB dose. TSA demonstrated that the cumulative Z curve crossed both the conventional test and trial sequential monitoring boundary for the macroscopic adhesion score. MB had a beneficial effect on intraperitoneal adhesion following laparotomy, and adhesions decreased with increase in dose.

Biomedical Applications of Chitosan and Its Derivative Nanoparticles

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely difficult to solubilize in water, but it can be solubilized in acidic solution. Its insolubility in water is a major limitation for its use in medical applications. Chitosan derivatives can be obtained by chemical modification using such techniques as acylation, alkylation, sulfation, hydroxylation, quaternization, esterification, graft copolymerization, and etherification. Modified chitosan has chemical properties superior to unmodified chitosan. For example, nanoparticles produced from chitosan derivatives can be used to deliver drugs due to their stability and biocompatibility. This review mainly focuses on the properties of chitosan, chitosan derivatives, and the origin of chitosan-based nanoparticles. In addition, applications of chitosan-based nanoparticles in drug delivery, vaccine delivery, antimicrobial applications, and callus and tissue regeneration are also presented. In summary, nanoparticles based on chitosan have great potential for research and development of new nano vaccines and nano drugs in the future.

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.

Polymer materials for prevention of postoperative adhesion

Postoperative adhesion (POA) is a common complication that often occurs after a variety of surgeries, such as plastic surgery, repair operations of abdominal, pelvic, and tendon, and so forth. Moreover, POA leads to chronic abdominal pain, secondary infertility in women, intestinal obstruction, and other severe complications, which significantly reduce the life quality of patients. In order to prevent the formation of POA, a number of strategies have been developed, among which an emerging method is physical barriers consisting of polymer materials. This review highlights the most commonly used natural and synthetic polymer materials in anti-adhesion physical barriers. The specific features of polymer materials are analyzed and compared, and the possible prospect is also predicted.

STATEMENT OF SIGNIFICANCE

Postoperative adhesion (POA) is a serious complication accompanied with various surgeries. Polymer material-based physical barriers have attracted a large amount of attention in POA prevention. The polymer barriers can effectively avoid the formation of fibrous tissues among normal organs by reducing the interconnection of injured tissues. In this review, specific features of the natural and synthetic polymer materials for application in POA prevention were presented, and the possible prospects were predicted. All in all, our work can provide inspiration for researchers to choose proper polymer materials for preclinical and even clinical anti-adhesion studies.

Effect of a Chitosan Gel on Hemostasis and Prevention of Adhesion After Endoscopic Sinus Surgery

OBJECTIVES

Postoperative bleeding and adhesion formation are the two most common complications after endoscopic sinus surgery (ESS). The former sometimes can be life threatening and the latter is the most common reason requiring revision surgery. This study was designed to evaluate the effect of newly developed chitosan gel (8% carboxymethyl chitosan, Surgi shield) on hemostasis and wound healing after ESS.

METHODS

A prospective, randomized, double-blind controlled trial was conducted in 33 patients undergoing symmetric ESS. At the conclusion of the operation, Surgi shield was randomly applied on one side of the nasal cavity, with the opposite side acting as control and the bleeding quantity of the surgical field was evaluated every 2 minutes. And then, Merocel was placed in the ethmoidectomized areas of the both sides. Five milliliters of Surgi shield was applied to the Merocel of intervention side and saline was applied to the other side. Merocel in both nasal cavities was removed and 5 mL of Surgi shield was applied again to the intervention side on the second day after surgery. The nasal cavity was examined using a nasal endoscope and the degree of adhesion, crusting, mucosal edema, infection, and granulations were graded at 1, 2, and 4 weeks after surgery.

RESULTS

Complete hemostasis was rapidly achieved in the Surgi shield applied side compared with the control side at 2, 4, 6, 8, and 10 minutes after application of Surgi shield (P=0.007, P=0.004, P<0.001, P=0.001, and P<0.001, respectively). There were significantly less adhesions on the Surgi shield applied side at postoperative 1, 2, and 4 weeks (P=0.001, P<0.001, and P<0.001, respectively). The degree of mucosal edema, infection, crusting, or granulation formation assessed by the endoscopic features in the Surgi shield applied side was not significantly different from that of the control side (P>0.05). No adverse effects were noted in the patient series.

CONCLUSION

Surgi shield containing chitosan can be used safely to achieve rapid hemostasis immediately after ESS and to prevent adhesion formation.

The efficacy and safety of chitosan dextran gel in a burr hole neurosurgical sheep model

BACKGROUND

Achieving and maintaining haemostasis is of paramount importance in neurosurgery. Chitosan has been shown in both animal and human models to be significantly effective in haemostasis as well as in reducing adhesion formation.

OBJECTIVES

To evaluate the haemostatic potential and to study histopathological changes caused by novel chitosan dextran gel in a neurosurgical sheep model.

METHOD

Ten sheep underwent neurosurgical burr hole procedure. Bleeding control was tested at the level of bone, dura and brain separately with both chitosan gel and Gelfoam paste on separate burr holes. Baseline bleeding was measured at the time of injury using the Boezaart scale, and then every 2 min after the application of each agent until complete haemostasis or 10 min, whichever was earlier. Safety was assessed through MRI scans and histopathological analysis.

RESULTS

Mixed modeling showed no statistical difference in time to haemostasis between chitosan gel and Gelfoam paste (means of log-normalized areas under the curve were 1.3688 and 1.3196 respectively) for each burr hole (p = 0.7768). Logistic regression modeling showed that Chitosan significantly decreased the incidence of bleeding beyond the first time point measured after application of the treatment when compared to Gelfoam (OR = 2.7, p = 0.04). Average edema volume (cm(3)) on post-operative MRI was 0.97 for Gelfoam and 1.11 for (p = 0.49) while average histology scores were 2.5 for Gelfoam versus 3.3 for chitosan (p = 0.32).

CONCLUSION

Chitosan dextran gel is an effective haemostatic agent to control bleeding in brain tissue. It is safe and nontoxic to neural tissue.

An FDA approved neurokinin-1 receptor antagonist is effective in reducing intraabdominal adhesions when administered intraperitoneally, but not orally

INTRODUCTION

Postoperative adhesions pose a continued healthcare problem. We previously demonstrated that intraperitoneal (i.p.) administration of a neurokinin-1 receptor antagonist (NK-1RA) at surgery reduces intraabdominal adhesions in rats. The NK-1RA aprepitant (Emend, Merck) is clinically approved for preventing postoperative nausea and vomiting; however, its effects on adhesion formation are unknown. Thus, we determined the effects of i.p. and oral administration of aprepitant on adhesion formation in a rat model.

METHODS

Adhesions were surgically induced in rats that were randomized to receive either one or five oral preoperative doses or a single intraoperative i.p. dose of aprepitant (50 mg/kg). Adhesions were scored at 7 days. In similar experiments using i.p. dosing, animals were sacrificed at 24 h and peritoneal fluid, and tissue were collected to assess fibrinolytic activity and tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) mRNA levels, respectively.

RESULTS

I.p. aprepitant reduced adhesion formation by 33% (p < 0.05) compared with controls while oral aprepitant had no effect. Compared to controls i.p. aprepitant reduced tPA activity by 55% (p < 0.05), increased PAI-1 mRNA levels by 140% (p < 0.05), and had no affect on tPA mRNA levels.

CONCLUSION

These data suggest that aprepitant maybe a useful pharmacologic agent for reducing adhesion formation clinically.

Effects of a novel chitosan gel on mucosal wound healing following endoscopic sinus surgery in a sheep model of chronic rhinosinusitis

INTRODUCTION

Postoperative bleeding and adhesion formation remain the two major problems after endoscopic sinus surgery (ESS). This study investigates the effect on adhesion formation and wound healing in a sheep model of chronic sinusitis of three topical agents: recombinant tissue factor (rTF, Dade Innovin, Marburg, Germany), poly-ethylene glycol (SprayGel, Confluent Surgical, Waltham, MA), and a novel chitosan-dextran derivative gel (CD, Department of Chemistry, University of Otago, Dunedin, New Zealand).

METHODS

Twenty sheep with chronic sinusitis underwent ESS with standardized mucosal injuries created on the lateral nasal wall and the ethmoid region. Injured areas were divided into four groups, and one of the three agents or control (no treatment) was randomly applied. The presence and severity of adhesions were noted and the healing was evaluated by taking brushings for ciliary beat frequency and biopsies of the injured regions at day 28, 56, 84, and 112 post initial surgery. The biopsy specimens were assessed for re-epithelialisation using light microscopy and scanning electron microscopy for reciliation. The cytobrush specimens assessed cilial function by measuring ciliary beat frequency.

RESULTS

CD significantly decreased lateral nasal wall and ethmoidal adhesions compared to tissue factor at all time points (5% vs. 25%, and 0 vs. 50%, respectively). There was a noticeable trend toward decreased adhesions on the lateral nasal wall and ethmoids in the SprayGel group (10% and 14%) and the CD group (10% and 0%) compared to controls (15% and 40%). The CD group had a significantly greater percentage of re-epithelialisation at day 28 and day 84 compared to the rTF group (70% vs. 33%, P < .001; 84.5% vs. 61%, P < 0.05). At day 28, the CD group was significantly more ciliated than control (62% vs. 31%, P < .01) and than rTF (62% vs. 23%, P < .001). This difference between CD and rTF reciliation remained significant at day 56 (67% vs. 40%, P < .05). In addition, the mean cilial grade for CD at day 112 was significantly better than control (1.9 vs. 2.7, P < .05).

CONCLUSION

In the sheep model of chronic sinusitis, CD significantly improves microscopic wound healing and reduces adhesion formation after ESS.

Sildenafil reduces postoperative adhesion formation in a rat uterine horn model

OBJECTIVE

The purpose of this experimental study was to evaluate the effect of oral sildenafil on postoperative adhesion formation in rats.

STUDY DESIGN

Thirty-two Wistar Albino rats were subjected to standardized lesion by cauterization of the uterine horn and abrasion of the adjacent parietal peritoneum. They were randomized to receive sildenafil at a daily dose of 15 mg/kg, 7.5mg/kg and 3.75 mg/kg or placebo. Sildenafil was administered by gavage 1h before the operation and daily for 5 days after the procedure. The extent and severity of adhesions were assessed on the 14th postoperative day.

RESULT(S)

The severity but not extent of adhesions in rats given 15 mg/kg sildenafil was significantly less when compared with the other groups (<0.001).

CONCLUSION

Sildenafil diminishes peritoneal adhesion formation in rat.

Agarose/collagen composite scaffold as an anti-adhesive sheet

The objective of this work was to find a new material or new technology to achieve satisfactory post-surgery anti-adhesion. An agarose/collagen composite sheet was developed to prevent mesenchymal cells and extracellular matrix from adhering on the lesion site, in which agarose formed uniaxial channels that hindered penetration and intercommunication of cells among pores in a 3D sheet. The tensile strength of the composite sheet in the designed ratio of agarose and collagen was over 17 MPa in dry and 2 MPa in wet, which was suitable and convenient to be sewed or operated on in other general surgery. In vitro and in vivo experimental results showed that fibroblasts, adult-derived adipose stem cells, could not penetrate into the sheet and formed a 3D tissue, and agarose did not degrade in three weeks. The demonstration that this sheet can prevent mesenchymal cells from penetrating in 3D and forming a tissue warrants the agarose-based composite for an anti-adhesive membrane.

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.

The effect of resveratrol on surgery-induced peritoneal adhesions in an experimental model

Adhesion formation is a common cause of complications following surgery. The aim of this study was to investigate the effect of resveratrol on intra-abdominal adhesion prevention in a rat model. Twenty one Wistar-Albino rats weighing 200-250 g were assigned to three groups, of 7 rats each. After a midline laparotomy was performed, a 1 cm area of the ceacum was abraded in two of the groups. They were then given either resveratrol (Group 1), or saline (Group 2) intraperitoneally. Group 3 rats (sham operation) received no treatment, without the serosal damage. On the 14th day, the rats were killed and the adhesion score was determined according to Mazuji's adhesion grade scale. The tissue levels of malondialdehyde (MDA), nitric oxide (NO), and reduced glutathione (GSH) were measured. The mean Mazuji's adhesion grade in the resveratrol group was 1.0 +/- 0.0, in the saline group 2.57 +/- 1.51, and zero in the sham operated group (p < 0.05 between the resveratrol group and saline group comparison). The levels of MDA and NO in the resveratrol group were significantly lower than those of the saline group (p < 0.001). The level of GSH in the resveratrol group was significantly higher than in the saline and sham operated groups (p < 0.001 and p < 0.001, respectively). Introduction of resveratrol into the peritoneal cavity at the time of surgery reduced adhesion formation effectively in this model. Resveratrol probably acts through reduction of lipid peroxidation products.