Adenoviral-mediated gene expression of hepatocyte growth factor prevents postoperative peritoneal adhesion in a rat model

Hepatocyte Growth Factor DNA Aptamer for Prevention of Postoperative Peritoneal Adhesion via Enhancement of Fibrinolysis and Inhibition of Mesothelial Mesenchymal Transition

Postoperative peritoneal adhesion (PPA) is a prevalent complication of abdominal surgery, posing a significant hindrance to postsurgical recovery. Although several strategies have been developed to alleviate and prevent adhesions, their efficacy remains unsatisfactory. For the first time, we studied the therapeutic effect and mechanism of our recently developed thermally stable oligonucleotide-based mimetics of hepatocyte growth factor (HGF DNA aptamer) to prevent PPA. The HGF DNA aptamer effectively inhibited canonical TGF-β1 signaling transduction, partially suppressing mesothelial mesenchymal transition. Additionally, the aptamer, respectively, upregulated and downregulated the expression of tissue plasminogen activator and plasminogen activator inhibitor 1, thereby enhancing fibrinolytic activity. As a pleiotropic factor, the HGF DNA aptamer also enhanced the migratory and proliferative capacities of mesothelial cells. Finally, the aptamer demonstrated a higher level of effectiveness in preventing PPAs than the commercially available antiperitoneal adhesion barrier, Seprafilm. Due to its therapeutic benefits, excellent stability, biosafety, cost-effectiveness, and versatility, the HGF DNA aptamer demonstrates promise for preventing PPA in future clinical settings.

Postsurgical Adhesions: Is There Any Prophylactic Strategy Really Working?

Postoperative adhesions are a frequent complication encountered after surgical procedures, mainly after intraperitoneal interventions. To this day, the pathophysiological mechanism behind the process of adhesions formation is not completely known. There are many strategies proposed as prophylaxis methods, involving surgical techniques, drugs or materials that prevent adhesions and even state of the art technologies such as nanoparticles or gene therapy. The aim of our review is to present these innovative approaches and techniques for postoperative adhesions prevention. After a thorough scientific database query, we selected 84 articles published in the past 15 years that were relevant to our topic. Despite all the recent groundbreaking discoveries, we are at an early stage of understanding the complexity of the adhesion formation mechanism. Further investigations should be made in order to create an ideal product for safe clinical use for prevention.

A combination of hybrid polydopamine-human keratinocyte growth factor nanoparticles and sodium hyaluronate for the efficient prevention of postoperative abdominal adhesion formation

Postoperative abdominal adhesion (PAA) is one of the more universal complications of abdominal surgery with a frequent incidence. Currently available keratinocyte growth factor (KGF)-based glues for the prevention of adhesions remain a great bottleneck since their long-term biological activity in vivo is insufficient. In this study, we fabricated hybrid polydopamine (PDA)-KGF nanoparticles (PDA-KGF NPs) by using an in situ self-assembly and polymerization method. The physicochemical properties of the PDA-KGF nanoparticles were systematically characterized. The effect of preventing PAA in rats was evaluated by using hybrid PDA-KGF NPs combined with hyaluronate (Ha). The expression levels of inflammatory factors and the degree of inflammatory cell infiltration in the injured peritoneum were evaluated by enzyme-linked immunosorbent assays and hematoxylin-eosin staining, respectively. The levels of phospho-Src expression were revealed by Western blotting. The degree of fibrosis and the density of deposited collagen fibers were measured with real-time reverse-transcription polymerase chain reaction and picrosirius red staining. The results indicated that the PDA-KGF NPs combined with Ha greatly prevented the incidence of abdominal adhesion s and promoted the repair of mesothelial cells in injured peritoneum. More importantly, the PDA-KGF NPs combined with Ha obviously reduced collagen deposition and fibrosis and inhibited the inflammatory response. Our results suggest that PDA-KGF NPs combined with Ha are promising barrier-like biomaterials for the effective prevention of postoperative tissue adhesion. STATEMENT OF SIGNIFICANCE: Postoperative abdominal adhesion (PAA) as an inevitable postoperative complication affected the quality of life of patients. Currently available methods for preventing adhesions mainly employ degradable biomaterials. Previous research demonstrated that a hybrid keratinocyte growth factor (KGF)-sodium hyaluronate (Ha) gel could prevent the formation of PAAs. However, its clinical outcomes are not satisfactory since their bioactivity in vivo is too short. In this article, we fabricated hybrid polydopamine (PDA)-KGF nanoparticles (PDA-KGF NPs), which extend KGF bioactivity, effectively prevent PAA. Moreover, PDA-KGF NPs could remarkably reduce both collagen deposition and fibrosis, inhibit the inflammatory response, and promote mesothelial regeneration. Overall, the PDA-KGF NPs combined with Ha exhibit efficient antiadhesion properties, may provide a promising clinical protocol for the prevention of PAA.

Small Bowel Obstruction Induced by Concurrent Postoperative Intra-Abdominal Adhesions and Small Bowel Fecal Materials in a Young Dog

A 7-month-old neutered male poodle dog presented with general deterioration and gastrointestinal symptoms after two separate operations: a jejunotomy for small-intestinal foreign body removal and an exploratory laparotomy for diagnosis and treatment of the gastrointestinal symptoms that occurred 1 month after the first surgery. The dog was diagnosed as having small-bowel obstruction (SBO) due to intra-abdominal adhesions and small-bowel fecal material (SBFM) by using abdominal radiography, ultrasonography, computed tomography, and laparotomy. We removed the obstructive adhesive lesion and SBFM through enterotomies and applied an autologous peritoneal graft to the released jejunum to prevent re-adhesion. After the surgical intervention, the dog recovered quickly and was healthy at 1 year after the surgery without gastrointestinal signs. To our knowledge, this study is the first report of a successful treatment of SBO induced by postoperative intra-abdominal adhesions and SBFM after laparotomies in a dog.

Electrospun Nanofibrous Membranes for Preventing Tendon Adhesion

Tendon injuries are frequent, and surgical interventions toward their treatment might result in significant clinical complications. Pretendinous adhesion results in the disruption of the normal gliding mechanism of a damaged tendon, painful movements, and an increased chance of rerupture in the future. To alleviate postsurgical tendon-sheath adhesions, many investigations have been directed toward the development of repair approaches using electrospun nanofiber scaffolds. Such methods mainly take advantage of nanofibrous membranes (NFMs) as physical barriers to prevent or minimize adhesion of a repaired tendon to its surrounding sheath. In addition, these nanofibers can also locally deliver antiadhesion and anti-inflammatory agents to reduce the risk of tendon adhesion. This article reviews recent advances in the design, fabrication, and characterization of nanofibrous membranes developed to serve as (i) biomimetic tendon sheaths and (ii) physical barriers. Various features of the membranes are discussed to present insights for further development of repair methods suitable for clinical practice.

Preperitoneal Fat Grafting Inhibits the Formation of Intra-abdominal Adhesions in Mice

BACKGROUND

Adhesion formation contributes to postoperative complications in abdominal and gynaecological surgery. Thus far, the prevention and treatment strategies have focused on mechanical barriers in solid and liquid form, but these methods are not in routine use. As autologous fat grafting has become popular in treatment of hypertrophic scars because of its immunomodulatory effects, we postulated that fat grafting could also prevent peritoneal adhesion through similar mechanisms.

METHODS

This was a control versus intervention study to evaluate the effect of fat grafting in the prevention on peritoneal adhesion formation. An experimental mouse model for moderate and extensive peritoneal adhesions was used (n = 4-6 mice/group). Adhesions were induced mechanically, and a free epididymal fat graft from wild type or CAG-DsRed mice was injected preperitoneally immediately after adhesion induction. PET/CT imaging and scaling of the adhesions were performed, and samples were taken for further analysis at 7 and 30 days postoperation. Macrophage phenotyping was further performed from peritoneal lavage samples, and the expression of inflammatory cytokines and mesothelial layer recovery were analysed from peritoneal tissue samples.

RESULTS

Fat grafting significantly inhibited the formation of adhesions. PET/CT results did not show prolonged inflammation in any of the groups. While the expression of anti-inflammatory and anti-fibrotic IL-10 was significantly increased in the peritoneum of the fat graft-treated group at 7 days, tissue-resident and repairing M2 macrophages could no longer be detected in the fat graft at this time point. The percentage of the continuous, healed peritoneum as shown by Keratin 8 staining was greater in the fat graft-treated group after 7 days.

CONCLUSIONS

Fat grafting can inhibit the formation of peritoneal adhesions in mice. Our results suggest that fat grafting promotes the peritoneal healing process in a paracrine manner thereby enabling rapid regeneration of the peritoneal mesothelial cell layer.

Pharmacological Mobilization and Recruitment of Stem Cells in Rats Stops Abdominal Adhesions After Laparotomy

Adhesions are a very common complication in the abdominal surgery. Animal studies and human trials have evaluated strategies designed to reduce and prevent postsurgical adhesions but few have an evidence base that justifies routine use. A strategy to prevent adhesions effectively remains an urgent need. We studied a reproducible model of intra-peritoneal adhesion formation in rats using laparotomy with several peritoneal sutures to produce the adhesions. Here we show that entraining endogenous stem cells into injury sites using the combined effect of AMD3100 and low-dose FK-506 (AF) can reduce the adhesion score significantly and abolish peritoneal adhesions in 45% of animals in a rat model of severe postsurgical intra-abdominal adhesions, compared with saline controls. Searching for mechanisms, we found AF treatment dramatically increased SDF-1 expressing cells, HGF expressing Ym1+ M2 macrophages and CD133+ stem cells in the injury sites of peritoneal surface at day 5 post-operation. Our results demonstrate that medically induced recruitment of autologous stem cells using AF significantly reduced postsurgical intra-abdominal adhesions. These findings suggest a novel effective therapeutic approach to preventing adhesions in patients.

In vivo expression of thrombospondin-1 suppresses the formation of peritoneal adhesion in rats

BACKGROUND

Formation of intraperitoneal adhesions is one of the major complications after abdominal surgery, which may lead to bowel obstruction. Thrombospondin 1 (TSP-1) is an extracellular matrix modulating glycoprotein during tissue regeneration and collagen deposition.

AIM

To evaluated the therapeutic potential of overexpressed TSP-1 in suppressing pelvic adhesion formations in rat models.

METHODS

Pelvic adhesion was induced in anesthetized rats by laparotomy cecal abrasion. The animals were randomly assigned to treatment of local application with Seprafilm (an antiadhesive bioresorbable membrane) or adenoviral vectors encoding mouse TSP-1 (AdTSP-1) on the surfaces of the injured cecum. The severity of the peritoneal adhesions was evaluated by blinded observers 14 d later.

RESULTS

Compared with control (no treatment) group, the application of Sperafilm significantly reduced the formation of adhesion band, and local administration of AdTSP-1 on the injured cecum the also attenuated the severity of peritoneal adhesion score. However, systemic delivery of AdTSP-1 did not affect the formation of adhesion.

CONCLUSION

We conclude that therapeutic approaches in inducing regional overexpression of TSP-1 may serve as alternative treatment strategies for preventing postoperative peritoneal adhesion.

Battling adhesions: from understanding to prevention

Adhesions represent a major burden in clinical practice, particularly following abdominal, intrauterine, pericardial and tendon surgical procedures. Adhesions are initiated by a disruption in the epithelial or mesothelial layer of tissue, which leads to fibrin adhesion sites due to the downregulation of fibrinolytic activity and an increase in fibrin deposition. Hence, the metabolic events involved in tissue healing, coagulation, inflammation, fibrinolysis and angiogenesis play a pivotal role in adhesion formation. Understanding these events, their interactions and their influence on the development of post-surgical adhesion is crucial for the development of effective therapies to prevent them. Mechanical barriers, antiadhesive agents and combination thereof are customarily used in the battle against adhesions. Although these systems seem to be effective at reducing adhesions in clinical procedures, their prevention remains still elusive, imposing the need for new antiadhesive strategies.

The Distribution of Vascular Endothelial Growth Factor (VEGF), Human Beta-Defensin-2 (HBD-2), and Hepatocyte Growth Factor (HGF) in Intra-Abdominal Adhesions in Children under One Year of Age

The regulatory role between ischemia related factors and antimicrobial peptides in congenital intra-abdominal adhesions has not yet been defined. The aim of this research was to investigate the appearance and relative distribution of VEGF, HBD-2, and HGF in congenital intra-abdominal adhesions compared with relatively healthy tissue controls. The study group material was obtained from 48 patients who underwent abdominal surgery due to partial or complete bowel obstruction. VEGF, HBD-2, and HGF were detected using immunohistochemistry methods and their relative distribution was evaluated by means of the semiquantitative counting method. The results were analyzed using nonparametric statistic methods. A moderate number of VEGF positive endotheliocytes were detected, but there was no statistically significant difference between the groups. In the experimental group, a moderate to high number of VEGF positive macrophages was observed. In control group tissues, such macrophages were seen in significantly lower number (U = 61.0, p = 0.001). The increase of VEGF positive cells indicates support of angiogenesis due to the hypoxic conditions in case of adhesion disease. The number of HBD-2 marked fibroblasts and macrophages was moderate to high, but only few positive endotheliocytes were observed. Persisting appearance of HBD-2 positive structures might be a result of the inflammatory process. Most specimens showed occasional HGF positive macrophages and fibroblasts and there was no statistically significant difference between the groups. The relatively weak appearance of HGF suggests that the lack of this factor promotes the formation of fibrotic changes in case of intra-abdominal adhesions.

The Potential of Mesothelial Cells in Tissue Engineering and Regenerative Medicine Applications

Injury to the serosa through injurious agents such as radiation, surgery, infection and disease results in the loss of the protective surface mesothelium and often leads to fibrous adhesion formation. Mechanisms that increase the rate of mesothialisation are therefore actively being investigated in order to reduce the formation of adhesions. These include intraperitoneal delivery of cultured mesothelial cells as well as administration of factors that are known to increase mesothelial proliferation and migration. An exciting alternative that has only recently received attention, is the possible role of mesothelial progenitor cells in the repair and regeneration of denuded serosal areas. Accumulating evidence suggests that such a population exists and under certain conditions is able to form a number of defined cell types indicating a degree of plasticity. Such properties may explain the extensive use of mesothelial cells in various tissue engineering applications including the development of vascular conduits and peripheral nerve replacements. It is likely that with the rapid explosion in the fields of tissue engineering and regenerative medicine, a greater understanding of the potential of mesothelial progenitor cells to repair, replace and possibly regenerate damaged or defective tissue will be uncovered.

Keratinocyte Growth Factor Combined with a Sodium Hyaluronate Gel Inhibits Postoperative Intra-Abdominal Adhesions

Postoperative intra-abdominal adhesion is a very common complication after abdominal surgery. One clinical problem that remains to be solved is to identify an ideal strategy to prevent abdominal adhesions. Keratinocyte growth factor (KGF) has been proven to improve the proliferation of mesothelial cells, which may enhance fibrinolytic activity to suppress postoperative adhesions. This study investigated whether the combined administration of KGF and a sodium hyaluronate (HA) gel can prevent intra-abdominal adhesions by improving the orderly repair of the peritoneal mesothelial cells. The possible prevention mechanism was also explored. The cecum wall and its opposite parietal peritoneum were abraded after laparotomy to induce intra-abdominal adhesion formation. Animals were randomly allocated to receive topical application of HA, KGF, KGF + HA, or normal saline (Control). On postoperative day 7, the adhesion score was assessed with a visual scoring system. Masson’s trichrome staining, picrosirius red staining and hydroxyproline assays were used to assess the magnitude of adhesion and tissue fibrosis. Cytokeratin, a marker of the mesothelial cells, was detected by immunohistochemistry. The levels of tissue plasminogen activator (tPA), interleukin-6 (IL-6), and transforming growth factor β1 (TGF-β1) in the abdominal fluid were determined using enzyme-linked immunosorbent assays (ELISAs). Western blotting was performed to examine the expression of the TGF-β1, fibrinogen and α-smooth muscle actin (α-SMA) proteins in the rat peritoneal adhesion tissue. The combined administration of KGF and HA significantly reduced intra-abdominal adhesion formation and fibrin deposition and improved the orderly repair of the peritoneal mesothelial cells in the rat model. Furthermore, the combined administration of KGF and HA significantly increased the tPA levels but reduced the levels of IL-6, tumor necrosis factor α (TNF-α) and TGF-β1 in the abdominal fluid. The expression levels of TGF-β1, fibrinogen and α-SMA protein and mRNA in the rat peritoneum or adhesion tissues were also down-regulated following the combined administration of KGF and HA. The combined administration of KGF and HA can significantly prevent postoperative intra-abdominal adhesion formation by maintaining the separation of the injured peritoneum and promoting mesothelial cell regeneration. The potential mechanism may be associated with rapid mesothelial cell repair in the injured peritoneum. This study suggests that combined administration of KGF and HA may be a promising pharmacotherapeutic strategy for preventing abdominal adhesions, which is worth further study, and has potential value in clinical applications.

Role of the peritoneal cavity in the prevention of postoperative adhesions, pain, and fatigue

A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO₂ pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N₂O to the CO₂ pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.

Comparison between the intraoperative use of polyvinyl chloride cover and surgical compresses for preventing postoperative adhesions

BACKGROUND/PURPOSE

Surgical compresses used for retraction during major abdominal and pelvic procedures lead to postoperative adhesion formation resulting from damage to the visceral peritoneum. This study investigates whether polyvinyl chloride (PVC) covers cause less postsurgical adhesion and inflammation than surgical compresses in an animal model.

METHODS

Female Wistar albino rats (n = 160) were divided into three groups (compress, PVC cover and control), which were then divided into 16 subgroups (n = 10/group). All animals underwent midline laparotomy and cecal abrasion. A metal retractor, which applies a constant force, was then placed on the small intestine for 2 h. In the control group, no material was placed under the retractor, whereas a surgical compress or PVC cover was placed in the experimental animals. Full-thickness small intestinal biopsies were obtained and examined by light and electron microscopy. The following parameters were evaluated: congestion, mesothelial proliferation, leukocyte migration and collagenization. Adhesions were scored according to the Nair, Knightly and Mazuji scoring systems.

RESULTS

All inflammation scores were significantly higher in the compress group than in the other two groups. However, no significant difference was observed between the PVC cover and control groups. Adhesions were more frequent in the compress group than in the other two groups, regardless of the scoring system used.

CONCLUSIONS

Surgical compresses used in abdominal and pelvic surgeries cause inflammation and adhesion. Contrary to surgical compresses, PVC covers do not cause inflammation and adhesion, which may considerably reduce adhesion-related complications in abdominopelvic surgeries.

Peritoneal adhesion index (PAI): proposal of a score for the "ignored iceberg" of medicine and surgery

Peritoneal adhesions describe a condition in which pathological bonds form between the omentum, the small and large bowels, the abdominal wall, and other intra-abdominal organs. Different classification systems have been proposed, but they do not resolve the underlying problem of ambiguity in the quantification and definition of adhesions. We therefore propose a standardized classification system of adhesions to universalize their definition based on the macroscopic appearance of adhesions and their diffusion to different regions of the abdomen. By scoring with these criteria, the peritoneal adhesion index (PAI) can range from 0 to 30, unambiguously specifying precise adhesion scenarios. The standardized classification and quantification of adhesions would enable different studies to more meaningfully integrate their results, thereby facilitating a more comprehensive approach to the treatment and management of this pathology.

Mesenchymal stem cells attenuate peritoneal injury through secretion of TSG-6

BACKGROUND

Mesothelial cell injury plays an important role in peritoneal fibrosis. Present clinical therapies aimed at alleviating peritoneal fibrosis have been largely inadequate. Mesenchymal stem cells (MSCs) are efficient for repairing injuries and reducing fibrosis. This study was designed to investigate the effects of MSCs on injured mesothelial cells and peritoneal fibrosis.

METHODOLOGY/PRINCIPAL FINDINGS

Rat bone marrow-derived MSCs (5 × 10(6)) were injected into Sprague-Dawley (SD) rats via tail vein 24 h after peritoneal scraping. Distinct reductions in adhesion formation; infiltration of neutrophils, macrophage cells; number of fibroblasts; and level of transforming growth factor (TGF)-β1 were found in MSCs-treated rats. The proliferation and repair of peritoneal mesothelial cells in MSCs-treated rats were stimulated. Mechanically injured mesothelial cells co-cultured with MSCs in transwells showed distinct increases in migration and proliferation. In vivo imaging showed that MSCs injected intravenously mainly accumulated in the lungs which persisted for at least seven days. No apparent MSCs were observed in the injured peritoneum even when MSCs were injected intraperitoneally. The injection of serum-starved MSCs-conditioned medium (CM) intravenously reduced adhesions similar to MSCs. Antibody based protein array of MSCs-CM showed that the releasing of TNFα-stimulating gene (TSG)-6 increased most dramatically. Promotion of mesothelial cell repair and reduction of peritoneal adhesion were produced by the administration of recombinant mouse (rm) TSG-6, and were weakened by TSG-6-RNA interfering.

CONCLUSIONS/SIGNIFICANCE

Collectively, these results indicate that MSCs may attenuate peritoneal injury by repairing mesothelial cells, reducing inflammation and fibrosis. Rather than the engraftment, the secretion of TSG-6 by MSCs makes a major contribution to the therapeutic benefits of MSCs.

Variation in stability of housekeeping genes in healthy and adhesion-related mesothelium

OBJECTIVE

To investigate the stability of various housekeeping genes (HKG) within healthy versus scarred peritoneal mesothelium. The use of HKG as internal controls for quantitative real-time polymerase chain reaction (qRT-PCR) studies is based on the assumption of their inherent stability. However, recent evidence suggests that this is not true for all HKG and that stability may be tissue specific and affected by certain pathologies.

DESIGN

Paired mesothelial (n = 10) and adhesion tissue samples (n = 10) were taken during laparoscopic surgery. The stability of 12 candidate reference genes in the mesothelial tissues were evaluated; these include ATP5b, SDHA, CYC1, 18S rRNA, RPL13A, ACTB, YWHAZ, TOP1, UBC, EIF4A2, GAPDH, and B2M.

SETTING

Hospital.

PATIENT(S)

Female patients undergoing laparoscopic gynecological surgery were recruited from the Princess Anne Hospital, United Kingdom.

INTERVENTION(S)

Assessment of HKG expression stability using geNorm algorithm software.

MAIN OUTCOME MEASURE(S)

Stability measure (M) generated by geometric averaging of multiple target genes and mean pairwise variation of genes.

RESULT(S)

The most stable HKGs observed across both healthy and adhesion-related mesothelium were found to be ACTB, YWHAZ, and CYC1. ACTB had a higher expression in healthy mesothelium compared with in peritoneal adhesion tissue.

CONCLUSION(S)

This study indicates that ACTB, YWHAZ, and CYC1 are the appropriate internal controls for qRT-PCR analysis in mesothelial gene expression studies. Published discrepancies in gene expression studies using the mesothelium may therefore be due in part to inappropriate HKG selection.

Prevention of peritoneal adhesions: a promising role for gene therapy

Adhesions are the most frequent complication of abdominopelvic surgery, yet the extent of the problem, and its serious consequences, has not been adequately recognized. Adhesions evolved as a life-saving mechanism to limit the spread of intraperitoneal inflammatory conditions. Three different pathophysiological mechanisms can independently trigger adhesion formation. Mesothelial cell injury and loss during operations, tissue hypoxia and inflammation each promotes adhesion formation separately, and potentiate the effect of each other. Studies have repeatedly demonstrated that interruption of a single pathway does not completely prevent adhesion formation. This review summarizes the pathogenesis of adhesion formation and the results of single gene therapy interventions. It explores the promising role of combinatorial gene therapy and vector modifications for the prevention of adhesion formation in order to stimulate new ideas and encourage rapid advancements in this field.

Pathophysiology and prevention of postoperative peritoneal adhesions

Peritoneal adhesions represent an important clinical challenge in gastrointestinal surgery. Peritoneal adhesions are a consequence of peritoneal irritation by infection or surgical trauma, and may be considered as the pathological part of healing following any peritoneal injury, particularly due to abdominal surgery. The balance between fibrin deposition and degradation is critical in determining normal peritoneal healing or adhesion formation. Postoperative peritoneal adhesions are a major cause of morbidity resulting in multiple complications, many of which may manifest several years after the initial surgical procedure. In addition to acute small bowel obstruction, peritoneal adhesions may cause pelvic or abdominal pain, and infertility. In this paper, the authors reviewed the epidemiology, pathogenesis and various prevention strategies of adhesion formation, using Medline and PubMed search. Several preventive agents against postoperative peritoneal adhesions have been investigated. Their role aims in activating fibrinolysis, hampering coagulation, diminishing the inflammatory response, inhibiting collagen synthesis or creating a barrier between adjacent wound surfaces. Their results are encouraging but most of them are contradictory and achieved mostly in animal model. Until additional findings from future clinical researches, only a meticulous surgery can be recommended to reduce unnecessary morbidity and mortality rates from these untoward effects of surgery. In the current state of knowledge, pre-clinical or clinical studies are still necessary to evaluate the effectiveness of the several proposed prevention strategies of postoperative peritoneal adhesions.

Cytokine orchestration in post-operative peritoneal adhesion formation

Peritoneal adhesions are a near inevitable occurrence after laparotomy and a major cause of both patient and physician misery. To date, clinical attempts at their amelioration have concentrated on manipulating the physical factors that affect their development despite a wealth of experimental data elucidating the molecular mechanisms that underlie their initiation, development and maturation. However, the advent of targeted, specific anti-cytokine agents as directed therapy for inflammatory and neoplastic conditions raises the prospect of a new era for anti-adhesion strategies. To harness this potential will require considerable cross-disciplinary collaboration and that surgeon-scientists propel themselves to the forefront of this emerging field.

Sphingosine kinase 1 gene transfer reduces postoperative peritoneal adhesion in an experimental model

BACKGROUND

Recovery of the surgically damaged mesothelial cell layer is a major process in reducing postoperative peritoneal adhesions. Sphingosine kinase (SPK) 1 is a signalling molecule involved in the regulation of proliferation and migration of various cell types. This study determined the effect of SPK-1 gene transfer on the recovery of damaged mesothelial cells and on peritoneal adhesion formation after surgery.

METHODS

Rat mesothelial cells were isolated and characterized by their expression of cytokeratin and vimentin. Their migration was determined by scratch wound motility assay. Cellular SPK-1 activity was measured by [gamma-32P]adenosine 5'-triphosphate incorporation. Wistar rats underwent laparotomy with subsequent caecum or uterine horn abrasion. Rats were randomized to either SPK-1 gene (Ad-SPK-1) transfer or control groups. The animals were killed 14 days after operation and peritoneal adhesions were graded.

RESULTS

Adenovirus-mediated SPK-1 gene transfer increased the cellular SPK-1 activity of mesothelial cells, leading to enhanced migration. Median adhesion scores were significantly lower in the Ad-SPK-1 group than in controls in both rat caecum (0.98 versus 2.60; P < 0.001) and rat uterine horn (0.28 versus 1.83; P < 0.001) models.

CONCLUSION

Adenovirus-mediated SPK-1 gene transfer promotes recovery of the surgically damaged mesothelial cell layer and prevents postoperative peritoneal adhesion formation.

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.