Mutant matrix metalloproteinase-9 reduces postoperative peritoneal adhesions in rats

A self-fused peptide-loaded hydrogel with injectability and tissue-adhesiveness for preventing postoperative peritoneal adhesions

Peritoneal adhesions commonly occur following abdominal or pelvic surgery and can cause serious complications. Currently, physical barriers are the primary approach used in clinical practice to prevent adhesion, although their effectiveness is frequently inadequate. In this study, we developed an injectable peptide-loaded hydrogel with multiple functions, including self-fusion, tissue-adhesiveness, anti-inflammation, anti-cell adhesion and anti-angiogenesis. To assess the effectiveness of these hydrogels, which are stabilized by dynamic imine bonds and acetal connections, in preventing postoperative abdominal adhesions, we utilized both a rat abdominal adhesion model and a rat model simulating repeated-injury adhesions. In comparison to the commercially available HA hydrogel, as-prepared hydrogels exhibited significant reductions in inflammation, fibrosis, and angiogenesis, leading to an obvious decrease in peritoneal adhesions. Moreover, this peptide-loaded hydrogel demonstrated an ideal degradation time, maintaining an in vivo viability for about 10 days. We believe this peptide-loaded hydrogel presents a promising solution for the challenging clinical issue of postoperative abdominal adhesions.

Impact of High-Molecular-Weight Hyaluronic Acid on Gene Expression in Rabbit Achilles Tenocytes In Vitro

(1) Background: Surgical tendon repair often leads to adhesion formation, leading to joint stiffness and a reduced range of motion. Tubular implants set around sutured tendons might help to reduce peritendinous adhesions. The lubricant hyaluronic acid (HA) is a viable option for optimizing such tubes with the goal of further enhancing the anti-adhesive effect. As the implant degrades over time and diffusion is presumed, the impact of HA on tendon cells is important to know. (2) Methods: A culture medium of rabbit Achilles tenocytes was supplemented with high-molecular-weight (HMW) HA and the growth curves of the cells were assessed. Additionally, after 3, 7 and 14 days, the gene expression of several markers was analyzed for matrix assembly, tendon differentiation, fibrosis, proliferation, matrix remodeling, pro-inflammation and resolution. (3) Results: The addition of HA decreased matrix marker genes, downregulated the fibrosis marker α-SMA for a short time and slightly increased the matrix-remodeling gene MMP-2. Of the pro-inflammatory marker genes, only IL-6 was significantly upregulated. IL-6 has to be kept in check, although IL-6 is also needed for a proper initial inflammation and efficient resolution. (4) Conclusions: The observed effects in vitro support the intended anti-adhesion effect and therefore, the use of HMW HA is promising as a biodegradable implant for tendon repair.

A functional PVA aerogel-based membrane obtaining sutureability through modified electrospinning technology and achieving promising anti-adhesion effect after cardiac surgery

Pericardial barrier destruction, inflammatory cell infiltration, and fibrous tissue hyperplasia, trigger adhesions after cardiac surgery. There are few anti-adhesion materials that are both functional and sutureable for pericardial reconstruction. Besides, a few studies have reported on the mechanism of preventing pericardial adhesion. Herein, a functional barrier membrane with sutureability was developed via a modified electrospinning method. It was composed of poly(l-lactide-co-caprolactone) (PLCL) nanofibers, poly(vinyl alcohol) (PVA) aerogel, and melatonin, named PPMT. The PPMT had a special microstructure manifested as a staggered arrangement of nanofibers on the surface and a layered macroporous aerogel structure in a cross-section. Besides providing the porosity and hydrophilicity obtained from PVA, the structure also had suitable mechanical properties for stitching due to the addition of PLCL nanofibers. Furthermore, it inhibited the proliferation of fibroblasts by suppressing the activation of Fas and P53, and achieved anti-inflammatory effects by affecting the activity of inflammatory cells and reducing the release of pro-inflammatory factors, such as interleukin 8 (IL-8) and tumor necrosis factor α (TNF-α). Finally, in vivo transplantation showed that it up-regulated the expression of matrix metalloproteinase-1 (MMP1) and tissue inhibitor of metalloproteinase-1 (TIMP1), and down-regulated the expression of Vinculin and transforming growth factor β (TGF-β) in the myocardium, thereby reducing the formation of adhesions. Collectively, these results demonstrate a great potential of PPMT membrane for practical application to anti-adhesion.

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A functional PVA aerogel-based membrane (PPMT) obtained sutureability through modified electrospinning technology.

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The primary mechanism to anti-adhesion of PPMT membrane was explored.

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Promising anti-adhesion effect of PPMT membrane was accomplished in pericardium reconstruction in rabbit.

Post-Operative Adhesions: A Comprehensive Review of Mechanisms

Post-surgical adhesions are common in almost all surgical areas and are associated with significant rates of morbidity, mortality, and increased healthcare costs, especially when a patient requires repeat operative interventions. Many groups have studied the mechanisms driving post-surgical adhesion formation. Despite continued advancements, we are yet to identify a prevailing mechanism. It is highly likely that post-operative adhesions have a multifactorial etiology. This complex pathophysiology, coupled with our incomplete understanding of the underlying pathways, has resulted in therapeutic options that have failed to demonstrate safety and efficacy on a consistent basis. The translation of findings from basic and preclinical research into robust clinical trials has also remained elusive. Herein, we present and contextualize the latest findings surrounding mechanisms that have been implicated in post-surgical adhesion formation.

Sterile Injury Repair and Adhesion Formation at Serosal Surfaces

Most multicellular organisms have a major body cavity containing vital organs. This cavity is lined by a mucosa-like serosal surface and filled with serous fluid which suspends many immune cells. Injuries affecting the major body cavity are potentially life-threatening. Here we summarize evidence that unique damage detection and repair mechanisms have evolved to ensure immediate and swift repair of injuries at serosal surfaces. Furthermore, thousands of patients undergo surgery within the abdominal and thoracic cavities each day. While these surgeries are potentially lifesaving, some patients will suffer complications due to inappropriate scar formation when wound healing at serosal surfaces defects. These scars called adhesions cause profound challenges for health care systems and patients. Therefore, reviewing the mechanisms of wound repair at serosal surfaces is of clinical importance. Serosal surfaces will be introduced with a short embryological and microanatomical perspective followed by a discussion of the mechanisms of damage recognition and initiation of sterile inflammation at serosal surfaces. Distinct immune cells populations are free floating within the coelomic (peritoneal) cavity and contribute towards damage recognition and initiation of wound repair. We will highlight the emerging role of resident cavity GATA6+ macrophages in repairing serosal injuries and compare serosal (mesothelial) injuries with injuries to the blood vessel walls. This allows to draw some parallels such as the critical role of the mesothelium in regulating fibrin deposition and how peritoneal macrophages can aggregate in a platelet-like fashion in response to sterile injury. Then, we discuss how serosal wound healing can go wrong, causing adhesions. The current pathogenetic understanding of and potential future therapeutic avenues against adhesions are discussed.

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.

The role of oral fluvastatin on postoperative peritoneal adhesion formation in an experimental rat model

BACKGROUND

Postoperative peritoneal adhesions are a momentousness complication after abdominal surgery. Although varied means have been used to prevent and treat adhesions, the effects have not been satisfactory. Fluvastatin, a HMG-CoA reductase inhibitors, exhibits a variety of pharmacological effects. Aim of this study was to evaluate the effect of fluvastatin on postoperative peritoneal adhesion formation.

METHODS

Seventy-five male Wistar rats weighting 220-250g were randomly assigned equally to three groups. Group A was given sham operation without treatment, Group B was the model group in which postoperative peritoneal adhesion model was created without medication, and Group C was given oral fluvastatin treatment after postoperative peritoneal adhesion model created. After laparotomy on day 7, macroscopic and pathological assessment were evaluated, IL-1β and t-PA in plasma were performed to measure, and tissue samples were taken to measure MMP-9 protein.

RESULTS

There were significant differences between the groups on adhesion grade (p < .05), IL-1β content of the plasma and t-PA activity of the adhesions (p < .05). The grading of adhesion demonstrated significant differences between all groups. The levels of the IL-1β content of plasma, t-PA activity and MMP-9 of adhesion showed pivotal changes in Group B compared with Group A and C, while the difference between Group A and C was not statistically significant.

CONCLUSION

Oral fluvastatin application could reduce formation of intra-abdominal adhesion by promoting expression of MMP-9 level, lowering the levels of IL-1β and increasing the activity of t-PA after abdominal surgery.

Modified Adenovirus Reduces De Novo Peritoneal Adhesions in Rats and Limits Off-Target Transfection. Role of EZH2 in Adhesion Formation

AIM OF THE STUDY

Adenovector encoding tissue plasminogen activator (tPA) was shown to reduce experimental peritoneal adhesion. We investigated the targeting potential of our modified adenovector, its ability to reduce adhesions and the epigenetic role of histone methyltransferase EZH2 in adhesion formation.

MATERIALS AND METHODS

Control lacZ, nonmodified tPA or modified tPA vectors were instilled in the peritoneal cavity after injury in de novo adhesions or after lysis of adhesions in recurrent adhesions. Adhesion severity was scored and adhesions and liver tissues were examined for adenovirus E4 gene and tPA mRNA expression. Levels of tPA, plasminogen activator inhibitor-1 (PAI-1), transforming growth factor-β1 (TGF-β1), and EZH2 expression were measured.

RESULTS

E4 transcripts were detected in adhesions of nonmodified and modified and in livers of nonmodified but not in livers of modified de novo adhesions. Both nonmodified (p = 0.021) and modified vectors (p = 0.036) reduced the severity of de novo adhesions compared to lacZ vector. Levels of tPA in nonmodified (p = 0.021) and modified adhesions (p = 0.001) were elevated while PAI-1 (p = 0.013 and p = 0.001, respectively) and TGF-β1 levels (p = 0.002 and p = 0.016, respectively) were reduced compared with lacZ group. All vectors were not expressed in recurrent adhesions and severity score were not different among groups. EZH2 levels were elevated in de novo nontreated (p = 0.001) and was further increased in recurrent (p = 0.001) nontreated adhesions compared with noninjured peritoneum.

CONCLUSION

Modified adenovirus successfully targeted de novo adhesions but not liver tissues and reduced the severity of de novo adhesions. EZH2 is involved in the development and progression of peritoneal adhesions.

Prevention and treatment of peritoneal adhesions in patients affected by vascular diseases following surgery: a review of the literature

Intra-abdominal adhesions are the most frequently occurring postoperative complication following abdomino-pelvic surgery. Abdominal and pelvic surgery can lead to peritoneal adhesion formation causing infertility, chronic pelvic pain, and intestinal obstruction. Laparoscopy today is considered the gold standard of care in the treatment of several abdominal pathologies as well as in a wide range of vascular diseases. Laparoscopy has several advantages in comparison to open surgery. These include rapid recovery times, shorter hospitalisation, reduced postoperative pain, as well as cosmetic benefits. The technological improvements in this particular surgical field along with the development of modern techniques and the acquisition of specific laparoscopic skills have allowed for its wider utilization in operations with fully intracorporeal anastomoses. Postoperative adhesions are caused by aberrant peritoneal healing and are the leading cause of postoperative bowel obstruction. The use of anti-adherence barriers is currently being advocated for their prevention. The outcome of the investigation showed adhesion formation inhibition without direct detrimental effects on anastomotic healing. Poor anasto-motic healing can provoke adhesions even in the presence of anti-adhesion barriers. This review gives a short overview on the current evidence on the pathophysiology and prevention of peritoneal adhesions.