Prevention of post-surgical abdominal adhesions by a novel biodegradable thermosensitive PECE hydrogel

Quercetin inhibits mesothelial-mesenchymal transition and alleviates postoperative peritoneal adhesions by blocking the TGF-β1/PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Carthami flos is a dried flower of the Asteraceae plant Carthamus tinctorius (L.). Danhong injection, composed of Carthami flos and Danshen can prevent the formation of postoperative peritoneal adhesions. Quercetin (QUE), an active compound of Carthami flos, has also been proved to prevent postoperative abdominal and uterine cavity adhesions. However, whether QUE is the key component in Carthami flos and the mechanism in preventing postoperative peritoneal adhesions has not been studied.

AIM OF THE STUDY

To predict whether QUE is the key molecule in Carthami flos and explore the effect and mechanism of QUE in preventing postoperative peritoneal adhesions.

MATERIALS AND METHODS

Drug composition and target analysis was used to predict the key component in Carthami flos. The method of cecum-sidewall abrasion was used to establish adhesion models, and the antiadhesion effect of QUE was evaluated with the adhesion scoring system. Network pharmacology was used to predict the targets and potential mechanism of QUE in preventing adhesion. The mechanism was further verified by immunofluorescence, Western blot, wound healing experiment, and molecular docking.

RESULTS

Quercetin was predicted to be the key to preventing postoperative peritoneal adhesions in Carthami flos. Animal experiments revealed that QUE effectively ameliorated adhesions and reduced the expression of mesothelial-mesenchymal transition (MMT) related markers and TGF-β1. Moreover, the TGF-β1/PI3K/AKT pathway was predicted via protein-protein interaction and Kyoto encyclopedia of Genes and Genomes enrichment analysis to play a crucial part in preventing adhesion by QUE. Furthermore, in vitro experiments and molecular docking demonstrated that QUE could block the TGF-β1/PI3K/AKT pathway through forming a stable combination with TβR-II, thereby inhibiting MMT and ameliorating peritoneal adhesion.

CONCLUSIONS

QUE can not only reduce postoperative TGF-β1 but also block the TGF-β1/PI3K/AKT pathway to inhibit MMT of mesothelial cells, and finally alleviate postoperative peritoneal adhesions. These findings may provide insights towards development of a safe and effective anti-adhesive drug for prevention of postoperative peritoneal adhesions.

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

Efficacy of gelatin sponge in the prevention of post-surgical intra-abdominal adhesion in a rat model

Although different products have been developed to prevent post-surgical adhesion, their efficacy remains unsatisfactory. This study aimed to evaluate the efficacy of the gelatin sponge in the prevention of post-surgical intra-abdominal adhesions in a rat model. Rats were randomly divided into sham, adhesion, and gelatin groups. All rats, except the sham group, underwent cecal abrasion to establish an adhesion model. After celiotomy, a sterile gelatin sponge was applied intra-abdominal on the abraded cecum in the gelatin group. Rats were sacrificed on day 14 post-surgery and intra-abdominal adhesions were evaluated and scored. Adhesion tissues were evaluated by histological, histochemical, and immunohistochemical analysis. Intra-abdominal adhesions were recorded in all rats of the adhesion group. Intra-abdominal application of gelatin sponge significantly (P < 0.001) reduced intra-abdominal adhesions by 91% in the gelatin group relative to the adhesion group. The histological analysis revealed a marked decrease (P < 0.001) in the inflammatory score and neovascularization in the gelatin group. The histochemical analysis found that gelatin sponge administration reduced adhesion formation and thickness of adhesion tissue. Moreover, gelatin sponge significantly (P < 0.0001) increased MMP-9 expression and decreased macrophage marker expression in adhesive tissue. This study revealed that the application of gelatin sponge markedly reduced the post-surgical intra-abdominal adhesions and suggests new guidance for using gelatin sponge as an anti-adhesive substance in clinical practice.

The Therapeutic Potential of Targeting Key Signaling Pathways as a Novel Approach to Ameliorating Post-Surgical Adhesions

BACKGROUND

Peritoneal adhesions (PA) are a common complication of abdominal operations. A growing body of evidence shows that inhibition of inflammation and fibrosis at sites of peritoneal damaging could prevent the development of intra-abdominal adhesions.

METHODS

A search of PubMed, Medline, CINAHL and Embase databases was performed using the keywords 'postsurgical adhesion', 'post-operative adhesion', 'peritoneal adhesion', 'surgery-induced adhesion' and 'abdominal adhesion'. Studies detailing the use of pharmacological and non-pharmacological agents for peritoneal adhesion prevention were identified, and their bibliographies were thoroughly reviewed to identify further related articles.

RESULTS

Several signaling pathways, such as tumor necrosis factor-alpha, tissue plasminogen activator, and type 1 plasminogen activator inhibitor, macrophages, fibroblasts, and mesothelial cells play a key part in the development of plasminogen activator. Several therapeutic approaches based on anti-PA drug barriers and traditional herbal medicines have been developed to prevent and treat adhesion formation. In recent years, the most promising method to prevent PA is treatment using biomaterial-based barriers.

CONCLUSION

In this review, we provide an overview of the pathophysiology of adhesion formation and various agents targeting different pathways, including chemical agents, herbal agents, physical barriers, and clinical trials concerning this matter.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Peritoneal adhesions: Occurrence, prevention and experimental models

Peritoneal adhesions (PA) are a postoperative syndrome with high incidence rate, which can cause chronic abdominal pain, intestinal obstruction, and female infertility. Previous studies have identified that PA are caused by a disordered feedback of blood coagulation, inflammation, and fibrinolysis. Monocytes, macrophages, fibroblasts, and mesothelial cells are involved in this process, and secreted signaling molecules, such as tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), tissue plasminogen activator (tPA), and type 1 plasminogen activator inhibitor (PAI-1), play a key role in PA development. There have been many attempts to prevent PA formation by anti-PA drugs, barriers, and other therapeutic methods, but their effectiveness has not been widely accepted. Treatment by biomaterial-based barriers is believed to be the most promising method to prevent PA formation in recent years. In this review, the pathogenesis, treatment approaches, and animal models of PA are summarized and discussed to understand the challenges faced in the biomaterial-based anti-PA treatments.

Intraperitoneal Administration of Telmisartan Prevents Postsurgical Adhesion Band Formation

BACKGROUND

Angiotensin II receptor blockers (ARBs) have a potential role in reducing inflammation and fibrosis. We have integrated systems and molecular biology approaches to investigate the therapeutic potential of ARBs in preventing postsurgical adhesion band formation.

MATERIAL AND METHODS

we have followed the ARRIVE guidelines point by point during experimental studies. Telmisartan (1 and 9 mg/kg), valsartan (1 and 9 mg/kg), and losartan (1 and 10 mg/kg) were administered intraperitoneally in different groups of male albino Wistar rat. After 7 d of treatment, macroscopic evidence and score of fibrotic bands based on scaling methods was performed. Moreover, the anti-inflammatory and antifibrosis effects of telmisartan on reduction of fibrotic bands were investigated by using histopathology, ELISA, and real-time polymerase chain reaction methods.

RESULTS

Telmisartan, but not losartan or valsartan, prevented the frequency as well as the stability of adhesion bands. Telmisartan appears to elicit anti-inflammatory responses by attenuating submucosal edema, suppressing proinflammatory cytokines, decreasing proinflammatory cell infiltration, and inhibiting oxidative stress at the site of peritoneal surgery. We also showed that telmisartan prevents fibrotic adhesion band formation by reducing excessive collagen deposition and suppression of profibrotic genes expression at the peritoneum adhesion tissues.

CONCLUSIONS

These results support the potential application of telmisartan in preventing postsurgical adhesion band formation by inhibiting key pathologic responses of inflammation and fibrosis in postsurgery patients.

A fibrin-coated pericardial extracellular matrix prevented heart adhesion in a rat model

As most surgical treatments pose a risk of tissue adhesion, methods to prevent adhesion are needed across various surgical fields. In this study, we investigated the use of a decellularized pericardium with fibrin glue to prevent rat heart adhesion. Porcine pericardia were decellularized by a high-hydrostatic pressure method. Cells adhered to the resulting pericardial extracellular matrix (ECM) during an in vitro cell-seeding test, but fibrin-coated pericardial ECM showed reduced cell adhesion. In a rat surgical model of heart adhesion, the fibrin-coated pericardial ECM did not adhere to the heart and mesothelial cell adhesion was observed on the ECM surface. Notably, the anti-adhesion effect of fibrin-coated pericardial ECM was observed 4 weeks after surgery. These results support the utility of fibrin-coated pericardial ECM as an adhesion prevention material for cardiovascular surgery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1088-1094, 2019.

The Small Molecule Inhibitor QLT-0267 Decreases the Production of Fibrin-Induced Inflammatory Cytokines and Prevents Post-Surgical Peritoneal Adhesions

Peritoneal adhesions develop after abdominal surgery, trauma or intraperitoneal infections, and have important consequences. The deposition of peritoneal fibrin is a common pathophysiological pathway for the formation of adhesions. Here, we aimed to examine the effects of fibrin-induced cytokine production on peritoneal mesothelial cells (PMCs), and to block the effects of fibrin using an integrin-linked kinase (ILK) inhibitor, QLT-0267. PMCs were cultured from the enzymatic disaggregation of rat omentum. After the PMCs were covered with fibrin, the expression of IL-1β, IL-6, TNFα and VEGF-A increased. This increase in cytokine production was attenuated by QLT-0267, which acted via the inhibition of both the ILK and focal adhesion kinase (FAK) pathways, and subsequently via the GSK-3β pathway. We found that QLT-0267 decreased both the severity of peritoneal adhesion and the serum levels of IL-6 in our post-surgical adhesion mouse model. In conclusion, our study provides novel evidence that fibrin-induced cytokine production may involve in the mechanism of peritoneal adhesion formation. Furthermore, the use of the small molecule inhibitor QLT-0267 is a new strategy in preventing peritoneal adhesion in patients undergoing abdominal surgery.

Thermo-responsive in-situ forming hydrogels as barriers to prevent post-operative peritendinous adhesion

In this study, we aimed to assess whether thermo-responsive in-situ forming hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) could prevent post-operative peritendinous adhesion. The clinical advantages of the thermo-responsive hydrogels are acting as barrier material to block penetration of fibroblasts, providing mobility and flexibility during application and enabling injection through a small opening to fill spaces of any shape after surgery. The thermo-responsiveness of hydrogels was determined to ensure their clinic uses. By grafting hydrophilic biopolymers chitosan (CS) and hyaluronic acid (HA) to PNIPAM, the copolymer hydrogels show enhanced water retention and lubrication, while reduced volume shrinkage during phase transition. In cell culture experiments, the thermo-responsive hydrogel has good biocompatibility and reduces fibroblast penetration. In animal experiments, the effectiveness of preventing post-operative peritendinous adhesion was studied in a rabbit deep flexor tendon model. From gross examination, histology, bending angles of joints, tendon gliding excursion and pull-out force, HA-CS-PNIPAM (HACPN) was confirmed to be the best barrier material to prevent post-operative peritendinous adhesion compared to PNIPAM and CS-PNIPAM (CPN) hydrogels and a commercial barrier film Seprafilm®. There was no significant difference in the breaking strength of HACPN-treated tendons and spontaneously healed ones, indicating HACPN hydrogel application did not interfere with normal tendon healing. We conclude that HACPN hydrogel can provide the best functional outcomes to significantly prevent post-operative tendon adhesion in vivo.

STATEMENT OF SIGNIFICANCE

We prepared thermo-responsive in-situ forming hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) to prevent post-operative peritendinous adhesion. The injectable barrier hydrogel could have better anti-adhesive properties than current commercial products by acting as barrier material to block penetration of fibroblasts, providing mobility and flexibility during application and enabling injection through a small opening to fill spaces of any shape after surgery. The effectiveness of preventing post-operative peritendinous adhesion was studied in a rabbit deep flexor tendon model. From gross examination, histology, bending angles of joints, tendon gliding excursion and pull-out force, HA-CS-PNIPAM (HACPN) was confirmed to be the best barrier material to prevent post-operative peritendinous adhesion compared to PNIPAM and CS-PNIPAM (CPN) hydrogels and a commercial barrier film Seprafilm®.

Evaluation of a series of silk fibroin protein-based nonwoven mats for use as an anti-adhesion patch for wound management in robotic surgery

A novel anti-adhesion nonwoven mat mainly composed of silk fibroin protein (SFP) was fabricated via the single-spinneret electrospinning technique. A series of SFP-based electrospun nonwoven mats containing additives of different synthetic polymer ratios, such as pure SFP, SFP/poly(vinyl alcohol) (PVA), SFP/polyethylene glycol (PEG), and SFP/polyethylene oxide (PEO) were produced and compared. All membranes were porous and had diameters of 324.02 ± 113.7, 308.86 ± 74.02, 366.22 ± 115.81, and 341.82 ± 119.42 nm, respectively. The average pore size for each membrane was 1.132 ± 0.99, 0.811 ± 0.424, 0.975 ± 0.741, and 0.784 ± 0.497 μm² . No nonwoven mats showed significant cytotoxicity toward fibroblast cells based on the results of MTT assays. Surprisingly, for all groups of SFP-based nonwoven mats, nitrate formation was reduced by up to 94.55 ± 14.50%, 92.16 ± 19.38%, 91.28 ± 28.375%, and 92.00 ± 12.64% in lipopolysaccharide-induced RAW 264.7 macrophages model. Tissue anti-adhesion potential was evaluated in an in vitro fibroblast cell adhesion model and in vivo wounded mice model. In vitro, the mean cell anti-adhesion percentage of fibroblast cells changed over time in the following order: PVA/SFP > SFP > PEG/SFP∼PEO/SFP. In vivo, SFP and PVA/SFP-treated groups both showed superior collagen regeneration and wound closure. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 221-230, 2018.

Preparation and investigation of a novel levobupivacaine in situ implant gel for prolonged local anesthetics

In this study, levobupivacaine (LBP) was successfully incorporated into implant application based on the concept of in situ gel (PECE). The physicochemical characterization (preparation, phase transition temperature, in vitro release) were investigated. The results of viscosity measurement showed that the preparations behaved like a fluid but formed a rigid gel when exposed to increasing temperature (37 °C). In vitro release, LBP was graduated released from the gels as time lapsed, suggesting that LBP was well entrapped in PECE in situ gels. As is shown in pharmacokinetic parameters, the half-life of LBP injection (2.7 h) was shorter than that of LBP in situ gels (23.9 h), suggesting that LBP injection was taken up by other tissues more rapidly than gels. The area under the curve of LBP in situ gels was 2.18 times the size of that of LBP injection (P< 0.05). In pharmacodynamic test, even after nine hours of injection, gel group could still maintain rather good anesthesia effect and rats' stinging reaction maintained at a relatively low level, which had obvious statistical differences compared to injection group.

Dual crosslinked hyaluronic acid nanofibrous membranes for prolonged prevention of post-surgical peritoneal adhesion

A HA NFM crosslinked with FeCl₃and BDDE shows prolonged degradation to prevent peritoneal adhesion.

Hydrogel-Based Drug Delivery Systems for Poorly Water-Soluble Drugs

Hydrogels are three-dimensional materials that can withstand a great amount of water incorporation while maintaining integrity. This allows hydrogels to be very unique biomedical materials, especially for drug delivery. Much effort has been made to incorporate hydrophilic molecules in hydrogels in the field of drug delivery, while loading of hydrophobic drugs has not been vastly studied. However, in recent years, research has also been conducted on incorporating hydrophobic molecules within hydrogel matrices for achieving a steady release of drugs to treat various ailments. Here, we summarize the types of hydrogels used as drug delivery vehicles, various methods to incorporate hydrophobic molecules in hydrogel matrices, and the potential therapeutic applications of hydrogels in cancer.

Prevention of peritoneal adhesions using polymeric rheological blends

The effectiveness of rheological blends of high molecular weight hyaluronic acid (HA) and low molecular weight hydroxypropyl methylcellulose (HPMC) in the prevention of peritoneal adhesions post-surgery is demonstrated. The physical mixture of the two carbohydrates increased the dwell time in the peritoneum while significantly improving the injectability of the polymer compared with HA alone. HA-HPMC treatment decreased the total adhesion area by ∼ 70% relative to a saline control or no treatment in a repeated cecal injury model in the rabbit. No significant cytotoxicity and minimal inflammation were associated with the blend. Furthermore, no chemical or physical processing was required prior to their use beyond simple mixing.

The PEG-PCL-PEG Hydrogel as an Implanted Ophthalmic Delivery System after Glaucoma Filtration Surgery; a Pilot Study

Currently, filtration surgery has been considered as the most effective therapy for glaucoma; however, the scar formation in the surgical area may often lead to failure to the procedure. An implanted drug delivery system may provide localized and sustained release of a drug over an extended period. Poly (ethylene glycol)-poly (ε-caprolactone)-poly (ethylene glycol) (PEG-PCL-PEG, PECE) hydrogel has been successfully synthesized and determined as thermosensitive and biocompatible. In order to overcome the limitations of common local ophthalmic medications, we investigated the function of a self-assembled PECE hydrogel as an intracameral injection-implanted drug carrier to inhibit the formation of postoperative scarring. Following bevacizumal-loaded hydrogel intracameral injection into rabbit eyes, the status of the bleb and filtration fistula formed following the filtering surgery were examined through pathologic evaluation. Due to the sustained release of bevacizumab from the hydrogel, neovascularization and scar formation were inhibited; moreover, there were no corneal abnormalities and other ocular tissue damage found in the rabbits. This suggests that the PECE hydrogel may be considered as the novel biomaterial with potential as a sustained release system in glaucoma filtering surgery. Further studies require in shedding the light on the subject.

Comparative studies of thermogels in preventing post-operative adhesions and corresponding mechanisms

Thermogelling PLGA–PEG–PLGA, PCGA–PEG–PCGA, and PCL–PEG–PCL triblock copolymers and their efficacies of prevention of post-surgical peritoneal adhesions in rabbits were investigated and compared.

Injectable and thermo-sensitive PEG-PCL-PEG copolymer/collagen/n-HA hydrogel composite for guided bone regeneration

A novel three-component biomimetic hydrogel composite was successfully prepared in this study, which was composed of triblock PEG-PCL-PEG copolymer (PECE), collagen and nano-hydroxyapatite (n-HA). The microstructure and thermo-responsibility of the obtained PECE/Collagen/n-HA hydrogel composite were characterized. Scanning electronic microscopy (SEM) showed that the composite exhibited an interconnected porous structure. The rheological analysis revealed that the composite existed good thermo-sensitivity. In vivo biocompatibility and biodegradability was investigated by implanting the hydrogel composite in muscle pouches of rats for 3, 7, and 14 days. Moreover, the osteogenic capacity was evaluated by means of implanting the composite material in cranial defects of New Zealand White rabbits for 4, 12 and 20 weeks. In vivo performances confirmed that the biodegradable PECE/Collagen/n-HA hydrogel composite had good biocompatibility and better performance in guided bone regeneration than the self-healing process. Thus the thermal-response PECE/Collagen/n-HA hydrogel composite had the great potential in bone tissue engineering.

Biodegradable and thermoreversible PCLA-PEG-PCLA hydrogel as a barrier for prevention of post-operative adhesion

Biodegradable polymers can serve as barriers to prevent the post-operative intestinal adhesion. Herein, we synthesized a biodegradable triblock copolymer poly(ɛ-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(ɛ-caprolactone-co-lactide) (PCLA-PEG-PCLA). The concentrated polymeric aqueous solution was injectable, and a hydrogel could be rapidly formed due to percolation of a self-assembled micelle network at the body temperature without requirement of any chemical reactions. This physical hydrogel retained its integrity in vivo for a bit more than 6 weeks and was eventually degraded due to hydrolysis. The synthesized polymer exhibited little cytotoxicity and hemolysis; the acute inflammatory response after implanting the hydrogel was acceptable, and the degradation products were less acidic than those of other polyester-containing materials. A rabbit model of sidewall defect-bowel abrasion was employed, and a significant reduction of post-operative peritoneal adhesion has been found in the group of in situ formed PCLA-PEG-PCLA hydrogels.