Implementation of phospholipids as pharmacological modalities for postoperative adhesions prevention

What is the impact of intraperitoneal surfactant administration against postoperative intraabdominal adhesion formation? an experimental study

Background/Aim

Surfactant is a surface-active substance that, in addition to its detergent effect, also has effects that reduce inflammation and fibrosis. Because of these effects, it was aimed herein to investigate the effect of intraperitoneal surfactant application on preventing postoperative peritoneal adhesion formation in a uterine horn adhesion model.

Materials and methods

Twenty-one Wistar albino rats were randomly divided into 3 groups (G1-G3), as follows: G1 (n = 7): control group. The abdomen was opened and then closed; G2 (n = 7): adhesion group. The abdomen was opened. Then, a 2-cm linear incision was made over the right uterine horn, 2 mL of isotonic saline was administered intraperitoneally, and the abdomen was closed; and G3 (n = 7): treatment group. The abdomen was opened, a 2-cm linear incision was made over the right uterine horn, 2 mL (70 mg/kg) of surfactant was administered intraperitoneally, and the abdomen was closed. After 15 days, the rats were euthanized, the abdomens were reopened, and adhesion scoring was performed. After the right uterine horns were removed and fixed with 10% formalin, appropriate sections were taken from the traumatized tissue, stained with Masson's trichrome, and fibrosis and inflammation scoring were performed.

Results

The adhesion area and intensity were significantly higher in G2 than in G1 and G3 (p = 0.001) and were similar in G1 and G3 (p = 0.165). While fibrosis and inflammation were significantly higher in G2 than in G1 and G3 (p = 0.001), there was no difference between G1 and G3 (p = 0.5).

Conclusion

Intraperitoneal surfactant administration at a dose of 70 mg/kg was found to be effective in preventing intraabdominal adhesion formation in a rat uterine horn model.

Current options for the prevention of postoperative intra-abdominal adhesions

Postoperative adhesions are the most common cause of morbidity after abdominal and pelvic surgery. The clinical manifestations of postoperative adhesions can manifest within a few weeks or even several years after the surgery. They result from peritoneal irritation caused by surgical trauma or intra-abdominal infection. Normal peritoneal healing relies on the balance between fibrin deposition and its degradation. In this paper-using information derived from the Medline, PubMed, and ScienceDirect databases-we briefly summarize the pathogenesis of postoperative intra-abdominal adhesions and various strategies for possible prevention.

Phospholipids, the Masters in the Shadows during Healing after Acute Myocardial Infarction

Phospholipids are major components of cell membranes with complex structures, high heterogeneity and critical biological functions and have been used since ancient times to treat cardiovascular disease. Their importance and role were shadowed by the difficulty or incomplete available research methodology to study their biological presence and functionality. This review focuses on the current knowledge about the roles of phospholipids in the pathophysiology and therapy of cardiovascular diseases, which have been increasingly recognized. Used in singular formulation or in inclusive combinations with current drugs, phospholipids proved their positive and valuable effects not only in the protection of myocardial tissue, inflammation and fibrosis but also in angiogenesis, coagulation or cardiac regeneration more frequently in animal models as well as in human pathology. Thus, while mainly neglected by the scientific community, phospholipids present negligible side effects and could represent an ideal target for future therapeutic strategies in healing myocardial infarction. Acknowledging and understanding their mechanisms of action could offer a new perspective into novel therapeutic strategies for patients suffering an acute myocardial infarction, reducing the burden and improving the general social and economic outcome.

The effect of natural surfactants on the development of postoperative intraabdominal adhesion

Background/aim

The development of postoperative adhesion after abdominal surgery is sometimes a severe problem. Our study investigates the effectiveness of exogenous surfactant application in preventing adhesion development in the experimental adhesion model.

Materials and methods

This randomized-controlled interventional study was carried out in the animal laboratory of Kahramanmaraş Sütçü İmam University between March 1 and March 31, 2020. An experimental intra-abdominal adhesion model was established in 24 adult female rats by cecal abrasion. Rats were randomly divided into four groups. Groups I, II, and III were taken intraperitoneally as beractant, poractant, and calfactant applied groups, respectively. Group IV was the control group. Relaparotomy was performed in all groups on the 15th postoperative day, and intra-abdominal adhesions were scored macroscopically according to the Canbaz scoring system. In addition, the cecal regions were evaluated microscopically and scored according to the Zühlke microscopic classification system. The scores of the groups were compared statistically.

Results

The Zühlke adhesion development score was significantly lower in the exogenous surfactant applied groups. In addition, when the surfactant-applied groups were compared among themselves, it was seen that the adhesion score in the beractant group was significantly better than the other surfactant types (p < 0.01).

Conclusion

Our study results showed that prophylactic intraperitoneal surfactant application significantly reduced postoperative adhesion development, particularly beractant.

Piperine Liposome-Embedded in Hyaluronan Hydrogel as an Effective Platform for Prevention of Postoperative Peritoneal Adhesion

This study aimed to prepare piperine (PIP) loaded liposomes in hyaluronic acid (HA) hydrogel to provide a hybrid superstructure for postoperative adhesion prevention. Liposomes were prepared using thin-film hydration method. The optimised formulation was characterised by size, SEM, TEM, FTIR, encapsulation efficiency (EE)% (w/w), and release pattern. Liposome-in-hydrogel formulation was investigated by rheology, SEM, and release studies. The efficacy was evaluated in a rat peritoneal abrasion model. EE% (w/w) increased with increasing lipid concentration from 10 to 30; however, a higher percentage of Chol reduced EE% (w/w). The optimised liposome (EE: 68.10 ± 4.18% (w/w), average diameter: 513 ± 14.67 nm, PDI: 0.15 ± 0.04) was used for hydrogel embedding. No sign of adhesion in 5/8 rats and no collagen deposition confirmed the in vivo effectiveness of the optimised formulation. Overall, providing a sustained delivery of PIP, the developed liposome-in-hydrogel formulation can be a promising carrier to prevent postoperative adhesion.

Lipid emulsions prevent postoperative abdominal adhesions

INTRODUCTION

Adhesions are the most common cause of long-term morbidity after abdominal surgery and most often cause various forms of intestinal passage disorders ranging from partial obstruction to complete, life-threatening intestinal obstruction. The aim of the present study was to evaluate the protective effect of intraperitoneally administered lipid emulsions on the formation of adhesions in larger animal model, as the lubricating effect of phospholipids and the mechanical barrier of the lipid component are combined with the anti-inflammatory effect of fish oil.

METHODS

Thirty-one female domestic pigs were randomly divided into three groups. At the end of the surgical procedure, a lipid emulsion or saline solution was applied intraperitoneally. After 14 days, an independent macroscopic, histological and immunohistochemical evaluation of the adhesions were performed.

RESULTS

Intraperitoneal administration of lipid emulsions significantly reduced the incidence of intra-abdominal adhesions. Microscopic examination demonstrated a significant reduction in the number of inflammatory elements and the amount of collagen in the adhesions, especially after administration of the fish oil-based emulsion. A simultaneous decrease in neovascularization was observed in the adhesions. Evaluation of the intestinal anastomosis did not reveal significant differences in healing between the groups.

CONCLUSION

Intraperitoneal administration of lipid emulsions can reduce the development of postoperative intra-abdominal adhesions by the combined action of phospholipids as important lubricants and lipids as a mechanical barrier. Their effect is caused by a reduction in proinflammatory and profibrotic mediators. At the same time, intraperitoneal administration of lipid emulsions does not impair healing of the anastomosis in larger animal model.

Inflammation Self-Limiting Electrospun Fibrous Tape via Regional Immunity for Deep Soft Tissue Repair

Overexpression of inflammatory cytokines and chemokines occurs at deep soft tissue injury sites impeding the inflammation self-limiting and impairing the tissue remodeling process. Inspired by the electrostatically extracellular matrix (ECM) binding property of the inflammatory signals, an inflammation self-limiting fibrous tape is designed by covalently modifying the thermosensitive methacrylated gelatin (GelMA) and negatively charged methacrylated heparin (HepMA) hydrogel mixture with proper ratio onto the electrospun fibrous membrane by mild alkali hydrolysis and carboxyl-amino condensation reaction to restore inflammation self-limiting and promote tissue repair via regional immunity regulation. While the GelMA guarantees cell compatibility, the negatively charged HepMA successfully adsorbs the inflammatory cytokines and chemokines by electrostatic interactions and inhibits immune cell migration in vitro. Furthermore, in vivo inflammation self-limiting and regional immunity regulation efficacy is evaluated in a rat abdominal hernia model. Reduced local inflammatory cytokines and chemokines in the early stage and increased angiogenesis and ECM remodeling in the later phase confirm that the tape is an approach to maintain an optimal regional immune activation level after soft tissue injury. Overall, the reported electrospun fibrous tape will find its way into clinical transformation and solve the challenges of deep soft tissue injury.

Indomethacin Sustained-Release Anti-adhesion Membrane Composed of a Phospholipid and Polycaprolactone Blend

Background

Postoperative peritoneal adhesions are among common challenging problems in surgery. The availability of limited efficient strategies to prevent intra-abdominal adhesion reinforces the need to explore new methods. Given the favorable prolonged drug release characteristics of polycaprolactone (PCL) films and their ability to act as a biodegradable physical barrier implant, along with the anti-inflammatory and anti-adhesion properties of indomethacin and phospholipids, this study hypothesized that indomethacin sustained-release membrane composed of phosphatidylcholine (PC) and PCL blend could efficiently prevent abdominal adhesion formation.

Methods

Different polymeric and polymeric/lipidic hybrid formulations with three feeding materials to drug weight ratios were prepared, and their physicochemical characteristics and drug release kinetics were evaluated and compared. Abdominal adhesions were induced in 48 rats by the abrasion of the cecum and excision of a section of the opposite abdominal wall. Adhesion formation was evaluated by macroscopic scoring, histological, scanning electron microscopy, and polymerase chain reaction analyses.

Results

Both PCL and PCL-PC films exhibited sustained indomethacin release profiles. The X-ray diffraction and Fourier-transform infrared spectroscopy studies confirmed indomethacin incorporation in formulations in molecular dispersion form without any interaction. The films showed smooth surfaces and good mechanical properties. The treatment with indomethacin PCL-PC membrane significantly reduced the expression levels of tumor necrosis factor-alpha, transforming growth factor-beta, interleukin-1, interleukin-6, and fibrinogen in the adhesion tissues. The separation of the injured peritoneum, very low adhesion scores, and complete mesothelial cell regeneration were also achieved.

Conclusions

This study suggests that indomethacin-eluting PCL-PC membrane acting through the combination of physical barrier, anti-inflammatory agents, and controlled drug delivery warrants an effective approach to prevent intra-abdominal adhesion.

Superhydrophilic PLGA-Graft-PVP/PC Nanofiber Membranes for the Prevention of Epidural Adhesion

Background

The frequent occurrence of failed back surgery syndrome (FBSS) seriously affects the quality of life of postoperative lumbar patients. Epidural adhesion is the major factor in FBSS.

Purpose

A safe and effective antiadhesion material is urgently needed.

Methods

A superhydrophilic PLGA-g-PVP/PC nanofiber membrane (NFm) was prepared by electrospinning. FTIR was performed to identify its successful synthesis. Scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and water contact angle measurement were performed. CCK-8 assays were performed in primary rabbit fibroblasts (PRFs) and RAW264.7 cells to explore the cytotoxicity of PLGA-g-PVP/PC NFm. Calcein-AM/PI staining was used to measure the adhesion status in PRFs. ELISA was performed to measure the concentrations of TNF-α and IL-10 in RAW264.7 cells. In addition, the anti-epidural adhesion efficacy of the PLGA-g-PVP/PC NFm was determined in a rabbit model of lumbar laminectomy.

Results

The PLGA-g-PVP/PC NFm exhibited ultrastrong hydrophilicity and an appropriate degradation rate. Based on the results of the CCK-8 assays, PLGA-g-PVP/PC NFm had no cytotoxicity to PRFs and RAW264.7 cells. Calcein-AM/PI staining showed that PLGA-g-PVP/PC NFm could inhibit PRF adhesion. ELISAs showed that PLGA-g-PVP/PC NFm could attenuate lipopolysaccharide-induced macrophage activation. In vivo experiments further confirmed the favorable anti-epidural adhesion effect of PLGA-g-PVP/PC NFm and the lack of a strong inflammatory response.

Conclusion

In this study, PLGA-g-PVP/PC NFm was developed successfully to provide a safe and effective physical barrier for preventing epidural adhesion. PLGA-g-PVP/PC NFm provides a promising strategy for preventing postoperative adhesion and has potential for clinical translation.

Curcumin polymeric membranes for postoperative peritoneal adhesion: Comparison of nanofiber vs. film and phospholipid-enriched vs. non-enriched formulations

Intra-abdominal adhesion remains a major postoperative problem and is able to place individuals at lifelong risk of serious complications. Among available approaches, insertion of a barrier membrane at the site of injury partially inhibited adhesion formation. Moreover, the local administration of an anti-adhesive agent showed some favorable effects. In this study, we aimed to prepare and fully characterize polycaprolactone (PCL)-based film casts and electrospun nanofibers (NFs) containing a natural anti-inflammatory agent, curcumin (CUR), with extended-release properties. We also compared their efficiencies in preventing tissue adhesions. Additionally, the impact of soy phosphatidylcholine (SPC) enrichment on adhesion prevention was investigated. Prepared membranes were evaluated in terms of surface morphology (SEM, AFM), surface wettability, CUR release profiles, structural properties (FTIR, XRD, DSC), and mechanical behaviors. To further analyze the anti-adhesion effectiveness, a cecal abrasion model was performed on rats. SEM and AFM images showed a smoother surface in SPC-containing films. Concerning NFs, uniform bead-free fibers were observed and SPC containing NFs showed higher conductivity and lower viscosity and therefore, smaller fibers. All formulations exhibited sustained drug release over 4 weeks. In vivo findings revealed the superior performance of films compared to NFs and phospholipid-enriched formulations over non-enriched ones. Among all film formulations and in comparison to the positive control (Seprafilm®), CUR-SPC-PCL films significantly reduced peritoneal adhesions, as evidenced by gross examination, histological evaluation and immunohistochemical (IHC) analysis. The remarkable in vivo anti-adhesion activity together with suitable in vitro properties have made CUR-SPC-PCL films a promising system for postoperative anti-adhesion purposes in the clinic.

Facile fabrication of phospholipid-functionalized nanofiber-based barriers with enhanced anti-adhesion efficiency

Electrospun nanofibrous membranes (NFMs) have attracted considerable attention as a potential physical barrier for reducing postoperative adhesion. However, no anti-adhesion barrier can completely prevent adhesion formation. In this study, phospholipid-functionalized NFMs were readily fabricated by one-step electrospinning to obtain nanofiber-based barriers with enhanced wettability and anti-adhesion efficiency. The optimized phospholipid NFMs were shown to have a fiber diameter of 831 nm ± 135 nm that is drastically decreasing, high porosity of 87.6 % ± 1.1 %, and superior hydrophilicity. Moreover, the phospholipid NFMs with excellent cytocompatibility exhibited fibroblasts being significantly reduced (≈ 51 %) after incubation of 3 days compared to that of the NFMs (≈ 96 %), confirming long-lasting anti-adhesion capability against fibroblasts. Meanwhile, less cell adhesion and proliferation of Raw 264.7 macrophages on NFM-10Lec indicated its superior anti-inflammatory effects. Thus, the facile phospholipid-functionalized nanofibers provided a promising strategy for anti-adhesion applications.

3D-Bioprinted Inflammation Modulating Polymer Scaffolds for Soft Tissue Repair

Development of inflammation modulating polymer scaffolds for soft tissue repair with minimal postsurgical complications is a compelling clinical need. However, the current standard of care soft tissue repair meshes for hernia repair is highly inflammatory and initiates a dysregulated inflammatory process causing visceral adhesions and postsurgical complications. Herein, the development of an inflammation modulating biomaterial scaffold (bioscaffold) for soft tissue repair is presented. The bioscaffold design is based on the idea that, if the excess proinflammatory cytokines are sequestered from the site of injury by the surgical implantation of a bioscaffold, the inflammatory response can be modulated, and the visceral adhesion formations and postsurgical complications can be minimized. The bioscaffold is fabricated by 3D-bioprinting of an in situ phosphate crosslinked poly(vinyl alcohol) polymer. In vivo efficacy of the bioscaffold is evaluated in a rat ventral hernia model. In vivo proinflammatory cytokine expression analysis and histopathological analysis of the tissues have confirmed that the bioscaffold acts as an inflammation trap and captures the proinflammatory cytokines secreted at the implant site and effectively modulates the local inflammation without the need for exogenous anti-inflammatory agents. The bioscaffold is very effective in inhibiting visceral adhesions formation and minimizing postsurgical complications.

Prevention of Intra-abdominal Adhesions by Electrical Stimulation

The study investigated the ability of transdermal electric stimulation to prevent the formation of intra-abdominal adhesions in the combination with Seprafilm^® (anti-adhesive agent). One hundred and twenty-eight (128) rabbits were subjected to a surgical procedure to simulate the adhesion processes. After the simulation, the animals were divided into 4 groups (32 animals each), depending on the application of the methods of prevention: (1) control group (no anti-adhesives or electro-stimulation) (CG); (2) comparison group (applications of Seprafilm^®) (SF); (3) comparison group 2 (transdermal electric stimulation of the abdominal muscles) TES; (4) group (transdermal electric stimulation + Seprafilm^®) (TES + SF). We observed that the application of the Seprafilm^® alone led to a significant decrease in the adhesive process compared to the control group (CG) (p < 0.01). The adhesion process in the group underwent transdermal electrical stimulation (TES) was significantly lower compared to the Seprafilm^® group (SF) (p ≤ 0.05). The results demonstrated a significant decrease in the adhesion processes in the SF + TES group on days 1, 3, 7 and 14 in comparison with the CG group (p = 0.001), SF group (p = 0.001) and TES group (p = 0.01) group of animals. This study showed the efficacy of transdermal electrical muscle stimulation for the prevention of intra-abdominal adhesions. Moreover, the combination of Seprafilm^® anti-adhesion agent and electrical muscle stimulation resulted in the complete absence of adhesions. Our findings indicate the potential of such strategy for further clinical application.