Genetic Predisposition of Postoperative Adhesions Varies in Substrains of BALB/c Mice.

Postoperative adhesions are a major clinical problem because of the associated infertility, chronic pain, bowel obstruction, and the associated costs. Variability in adhesion formation was suggested by clinical observations that apparently similar interventions can cause little to severe adhesions. This is supported by the presence of polymorphisms and genetic predisposition to develop adhesions in animal models and humans. We previously demonstrated differences in postoperative adhesions between different mouse strains. In this study, we aimed to investigate the variability in adhesion formation in inbred substrains of BALB/c mice. Since genetic differences in inbred substrains are minimal, they might be an opportunity to tackle the genetics of adhesion formation.

Pneumoperitoneum induced mesothelial cell changes in a laparoscopic mouse model.

BACKGROUND: CO2 pneumoperitoneum (PP) during laparoscopic surgery, can cause hypoxia and desiccation in the peritoneal mesothelial cell, resulting in a time-dependent retraction and bulging of these cells, an acute inflammatory reaction and enhanced adhesion formation. Since hypoxia is prevented by adding 4% of oxygen (O2) to the CO2 PP, the aim of this study was to evaluate the effect of adding 4% O2 to the CO2 PP on mesothelial cell morphology. METHODS: In a standardized laparoscopic mouse model (n=8 mice per group), a control group with a 30- or 60-min PP with humidified CO2 + 4% of O2 (groups I and II) was compared to a hypoxic group with 30- or 60-min humidified pure CO2 (groups III and IV) and a desiccation group with 60-min of dry CO2 PP (group V). The effect upon the peritoneum morphology was evaluated by scanning electron microscopy (SEM) of abdominal wall peritoneal biopsies. Biopsies, taken immediately (n=4) and 24 hrs (n=4) after surgery, were compared to a group without PP (group VI, n=4). SEM pictures were blindly scored for cell retraction, deletion of microvilli, fibrin deposition, holes in the epithelial layer and visibility of cell borders using a semi-quantitative scoring system. RESULTS: PP Hypoxia (CO2 PP) has a deleterious effect upon mesothelial morphology, immediately (holes: p= 0.04) and 24 hrs later (cell retraction: p=0.005; total score: p=0.03) . Desiccation has also a deleterious effect immediately (microvilli p=0.0090; fibrin deposition p=0.05) and 24 hrs after surgery (cell retraction: p=0.0036; holes: p=0.0004; microvilli: p< 0.0001, fibrin deposition: p=0.0225; borders: p=0.0007). This deleterious effect increases with duration of CO2 PP, affecting cell retraction (p=0.016), holes (p=0.0441), and the total score (p=0.0488). The addition of 4% of O2 to the CO2 PP failed to reach statistical significance. CONCLUSIONS: These data confirm that CO2 PP and dry gas have a deleterious effect on mesothelial cell morphology. Humidification of the insufflation gas reduces this deleterious effect. The hypothesis of a protective effect of adding O2 failed to reach significance.

Phase I/II Trial of Liver-derived Mesenchymal Stem Cells in Pediatric Liver-based Metabolic Disorders: A Prospective, Open Label, Multicenter, Partially Randomized, Safety Study of One Cycle of Heterologous Human Adult Liver-derived Progenitor Cells (HepaStem) in Urea Cycle Disorders and Crigler-Najjar Syndrome Patients.

BACKGROUND: Regenerative medicine using stem cell technology is an emerging field that is currently tested for inborn and acquired liver diseases. OBJECTIVE: This phase I/II prospective, open label, multicenter, randomized trial aimed primarily at evaluating the safety of Heterologous Human Adult Liver-derived Progenitor Cells (HepaStem) in pediatric patients with urea cycle disorders (UCDs) or Crigler-Najjar (CN) syndrome 6 months posttransplantation. The secondary objective included the assessment of safety up to 12 months postinfusion and of preliminary efficacy. METHODS: Fourteen patients with UCDs and 6 with CN syndrome were divided into 3 cohorts by body weight and intraportally infused with 3 doses of HepaStem. Clinical status, portal vein hemodynamics, morphology of the liver, de novo detection of circulating anti-human leukocyte antigen antibodies, and clinically significant adverse events (AEs) and serious adverse events to infusion were evaluated by using an intent-to-treat analysis. RESULTS: The overall safety of HepaStem was confirmed. For the entire study period, patient-month incidence rate was 1.76 for the AEs and 0.21 for the serious adverse events, of which 38% occurred within 1 month postinfusion. There was a trend of higher events in UCD as compared with CN patients. Segmental left portal vein thrombosis occurred in 1 patient and intraluminal local transient thrombus in a second patient. The other AEs were in line with expectations for catheter placement, cell infusion, concomitant medications, age, and underlying diseases. CONCLUSIONS: This study led to European clinical trial authorization for a phase II study in a homogeneous patient cohort, with repeated infusions and intermediate doses.

N2O strongly prevents adhesion formation and postoperative pain in open surgery through a drug-like effect.

BACKGROUND: Microsurgical tenets and peritoneal conditioning during laparoscopic surgery (LS) decrease postoperative adhesions and pain. For a trial in human, the strong beneficial effects of N2O needed to be confirmed in open surgery (OS). RESULTS: In a mouse model for OS, the effect of the gas environment upon adhesions was evaluated. Experiment I evaluated desiccation and the duration of exposure to CO2, N2O or CO2 + 4%O2. Experiment II evaluated the dose-response curve of adding N2O to CO2. Experiment III compared humidified CO2 + 10% N2O during LS and OS.In OS, 30- and 60-min exposure to non-humidified CO2 caused mortality of 33 and 100%, respectively. Mortality was prevented by humidification, by dry N2O or dry CO2 + 4%O2. Adhesions increased with the duration of exposure to CO2 (p < 0.0001) and decreased slightly by humidification or by the addition of 4% O2. N2O strongly decreased adhesions at concentrations of 5% or greater. With humidified CO2 + 10% N2O, adhesion formation was similar in OS and LS. CONCLUSIONS: The drug-like and strong beneficial effect of low concentrations of N2O is confirmed in OS.

Dominant hand, non-dominant hand, or both? The effect of pre-training in hand-eye coordination upon the learning curve of laparoscopic intra-corporeal knot tying.

BACKGROUND: Training of basic laparoscopic psychomotor skills improves both acquisition and retention of more advanced laparoscopic tasks, such as laparoscopic intra-corporeal knot tying (LICK). This randomized controlled trial (RCT) was performed to evaluate the effect of different pre-training programs in hand-eye coordination (HEC) upon the learning curve of LICK. RESULTS: The study was performed in a private center in Asunción, Paraguay, by 60 residents/specialists in gynaecology with no experience in laparoscopic surgery. Participants were allocated in three groups. In phase 1, a baseline test was performed (T1, three repetitions). In phase 2, participants underwent different training programs for HEC (60 repetitions): G1 with both the dominant hand (DH) and the non-dominant hand (NDH), G2 with the DH only, G3 none. In phase 3, a post HEC/pre LICK training test was performed (T2, three repetitions). In phase 4, participants underwent a standardized training program for LICK (60 repetitions). In phase 5, a final test was performed (T3, three repetitions). The score was based on the time taken for task completion system. The scores were plotted and non-linear regression models were used to fit the learning curves to one- and two-phase exponential decay models for each participant (individual curves) and for each group (group curves). For both HEC and LICK, the group learning curves fitted better to the two-phase exponential decay model. For HEC with the DH, G1 and G2 started from a similar point, but G1 reached a lower plateau at a higher speed. In G1, the DH curve started from a lower point than the NDH curve, but both curves reached a similar plateau at comparable speeds. For LICK, all groups started from a similar point, but immediately after HEC training and before LICK training, G1 scored better than the others. All groups reached a similar plateau but with a different decay, G1 reaching this plateau faster than the others groups. CONCLUSIONS: This study demonstrates that pre-training in HEC with both the DH and the NDH shortens the LICK learning curve.

A randomized control trial to evaluate the importance of pre-training basic laparoscopic psychomotor skills upon the learning curve of laparoscopic intra-corporeal knot tying.

BACKGROUND: Training of basic laparoscopic psychomotor skills improves the acquisition of more advanced laparoscopic tasks, such as laparoscopic intra-corporeal knot tying (LICK). This randomized controlled trial was designed to evaluate whether pre-training of basic skills, as laparoscopic camera navigation (LCN), hand-eye coordination (HEC), and bimanual coordination (BMC), and the combination of the three of them, has any beneficial effect upon the learning curve of LICK. The study was carried out in a private center in Asunción, Paraguay, by 80 medical students without any experience in surgery. Four laparoscopic tasks were performed in the ENCILAP model (LCN, HEC, BMC, and LICK). Participants were allocated to 5 groups (G1-G5). The study was structured in 5 phases. In phase 1, they underwent a base-line test (T1) for all tasks (1 repetition of each task in consecutive order). In phase 2, participants underwent different training programs (30 consecutive repetitions) for basic tasks according to the group they belong to (G1: none; G2: LCN; G3: HEC; G4: BMC; and G5: LCN, HEC, and BMC). In phase 3, they were tested again (T2) in the same manner than at T1. In phase 4, they underwent a standardized training program for LICK (30 consecutive repetitions). In phase 5, they were tested again (T3) in the same manner than at T1 and T2. At each repetition, scoring was based on the time taken for task completion system. RESULTS: The scores were plotted and non-linear regression models were used to fit the learning curves to one- and two-phase exponential decay models for each participant (individual curves) and for each group (group curves). The LICK group learning curves fitted better to the two-phase exponential decay model. From these curves, the starting points (Y0), the point after HEC training/before LICK training (Y1), the Plateau, and the rate constants (K) were calculated. All groups, except for G4, started from a similar point (Y0). At Y1, G5 scored already better than the others (G1 p = .004; G2 p = .04; G3 p < .0001; G4 NS). Although all groups reached a similar Plateau, G5 has a quicker learning than the others, demonstrated by a higher K (G1 p < 0.0001; G2 p < 0.0001; G3 p < 0.0001; and G4 p < 0.0001). CONCLUSIONS: Our data confirms that training improves laparoscopic skills and demonstrates that pre-training of all basic skills (i.e., LCN, HEC, and BMC) shortens the LICK learning curve.

Targeting mast cells: a new way to treat endometriosis.

INTRODUCTION: Endometriosis is a chronic estrogen-dependent inflammatory disease of unclear etiology that affects 15-20% of women of reproductive age. Efforts are now focusing on understanding new mechanisms involved in its physiopathology, like novel target pathways and different molecules. There is evidence that mast cells (MCs) play a role in this disease. This article summarizes recent achievements in preclinical studies and clinical activities investigating the role of MCs in endometriosis. Targeting MCs might offer new alternatives to treat this disease. Areas covered: A systematic literature search was performed (PubMed, Cochrane Library and ClinicalTrials.gov) using the keywords 'endometriosis and mast cells'. All relevant articles (34) found in PubMed were examined and their reference lists reviewed in order to pinpoint further studies for potential inclusion. Expert opinion: Since endometriosis is a multifactorial disease, and considering that numbers of MCs and activated MCs were clearly increased in endometriotic lesions in both animals and humans, use of MC stabilizers and inhibitors may prove to be effective to treat endometriosis and its associated pain. However, more data from preclinical studies and clinical trials will help to better define the status of MCs in the treatment of this pathology.

Prognostic relevance of molecular subtypes and master regulators in pancreatic ductal adenocarcinoma.

BACKGROUND: Pancreatic cancer is poorly characterized at genetic and non-genetic levels. The current study evaluates in a large cohort of patients the prognostic relevance of molecular subtypes and key transcription factors in pancreatic ductal adenocarcinoma (PDAC). METHODS: We performed gene expression analysis of whole-tumor tissue obtained from 118 surgically resected PDAC and 13 histologically normal pancreatic tissue samples. Cox regression models were used to study the effect on survival of molecular subtypes and 16 clinicopathological prognostic factors. In order to better understand the biology of PDAC we used iRegulon to identify transcription factors (TFs) as master regulators of PDAC and its subtypes. RESULTS: We confirmed the PDAssign gene signature as classifier of PDAC in molecular subtypes with prognostic relevance. We found molecular subtypes, but not clinicopathological factors, as independent predictors of survival. Regulatory network analysis predicted that HNF1A/B are among thousand TFs the top enriched master regulators of the genes expressed in the normal pancreatic tissue compared to the PDAC regulatory network. On immunohistochemistry staining of PDAC samples, we observed low expression of HNF1B in well differentiated towards no expression in poorly differentiated PDAC samples. We predicted IRF/STAT, AP-1, and ETS-family members as key transcription factors in gene signatures downstream of mutated KRAS. CONCLUSIONS: PDAC can be classified in molecular subtypes that independently predict survival. HNF1A/B seem to be good candidates as master regulators of pancreatic differentiation, which at the protein level loses its expression in malignant ductal cells of the pancreas, suggesting its putative role as tumor suppressor in pancreatic cancer. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov under the number NCT01116791 (May 3, 2010).

Oxidative stress in the pelvic cavity and its role in the pathogenesis of endometriosis.

Endometriosis is a disorder associated with a general inflammatory response in the peritoneal cavity. Oxidative stress is a potential factor involved in the pathophysiology of this disease, and reactive oxygen species (ROS) are implicated in this process. Indeed, in healthy individuals, ROS and antioxidants are in balance, but when balance is tipped toward an overabundance of ROS, oxidative stress occurs and can impact the entire reproductive lifespan of a woman. Reactive oxygen species are intermediaries produced by normal oxygen metabolism but are known to have deleterious effects. Excessive release of ROS induces cellular damage and alters cellular function by regulating protein activity and gene expression, leading to harmful effects. To protect themselves, cells have developed antioxidant systems to limit production of ROS, inactivate them, and repair cell damage. Understanding of the control of hemoglobin, heme, and iron-induced redox balance in endometriosis led us to propose a number of hypotheses to explain why oxidative stress is induced in case of pelvic endometriosis. Erythrocytes, apoptotic endometrial tissue, and cell debris transplanted into the peritoneal cavity by menstrual reflux and macrophages have all been cited as potential inducers of oxidative stress. Erythrocytes are likely to release pro-oxidant and proinflammatory factors, such as hemoglobin and its highly toxic by-products heme and iron, into the peritoneal environment. Iron and heme are essential to living cells, but unless appropriately chelated, free iron, and to a lesser extent heme, play a key role in the formation of deleterious ROS.

Identification of drugs that restore primary cilium expression in cancer cells.

The development of cancer is often accompanied by a loss of the primary cilium, a microtubule-based cellular protrusion that functions as a cellular antenna and that puts a break on cell proliferation. Hence, restoration of the primary cilium in cancer cells may represent a novel promising approach to attenuate tumor growth. Using a high content analysis-based approach we screened a library of clinically evaluated compounds and marketed drugs for their ability to restore primary cilium expression in pancreatic ductal cancer cells. A diverse set of 118 compounds stimulating cilium expression was identified. These included glucocorticoids, fibrates and other nuclear receptor modulators, neurotransmitter regulators, ion channel modulators, tyrosine kinase inhibitors, DNA gyrase/topoisomerase inhibitors, antibacterial compounds, protein inhibitors, microtubule modulators, and COX inhibitors. Certain compounds also dramatically affected the length of the cilium. For a selection of compounds (Clofibrate, Gefitinib, Sirolimus, Imexon and Dexamethasone) their ability to restore ciliogenesis was confirmed in a panel of human cancer cell line models representing different cancer types (pancreas, lung, kidney, breast). Most compounds attenuated cell proliferation, at least in part through induction of the primary cilium, as demonstrated by cilium removal using chloral hydrate. These findings reveal that several commonly used drugs restore ciliogenesis in cancer cells, and warrant further investigation of their antineoplastic properties.

Phospholipid profiling identifies acyl chain elongation as a ubiquitous trait and potential target for the treatment of lung squamous cell carcinoma.

Lung cancer is the leading cause of cancer death. Beyond first line treatment, few therapeutic options are available, particularly for squamous cell carcinoma (SCC). Here, we have explored the phospholipidomes of 30 human SCCs and found that they almost invariably (in 96.7% of cases) contain phospholipids with longer acyl chains compared to matched normal tissues. This trait was confirmed using in situ 2D-imaging MS on tissue sections and by phospholipidomics of tumor and normal lung tissue of the L-IkkαKA/KA mouse model of lung SCC. In both human and mouse, the increase in acyl chain length in cancer tissue was accompanied by significant changes in the expression of acyl chain elongases (ELOVLs). Functional screening of differentially expressed ELOVLs by selective gene knockdown in SCC cell lines followed by phospholipidomics revealed ELOVL6 as the main elongation enzyme responsible for acyl chain elongation in cancer cells. Interestingly, inhibition of ELOVL6 drastically reduced colony formation of multiple SCC cell lines in vitro and significantly attenuated their growth as xenografts in vivo in mouse models. These findings identify acyl chain elongation as one of the most common traits of lung SCC discovered so far and pinpoint ELOVL6 as a novel potential target for cancer intervention.

p53 attenuates AKT signaling by modulating membrane phospholipid composition.

The p53 tumor suppressor is the central component of a complex network of signaling pathways that protect organisms against the propagation of cells carrying oncogenic mutations. Here we report a previously unrecognized role of p53 in membrane phospholipids composition. By repressing the expression of stearoyl-CoA desaturase 1, SCD, the enzyme that converts saturated to mono-unsaturated fatty acids, p53 causes a shift in the content of phospholipids with mono-unsaturated acyl chains towards more saturated phospholipid species, particularly of the phosphatidylinositol headgroup class. This shift affects levels of phosphatidylinositol phosphates, attenuates the oncogenic AKT pathway, and contributes to the p53-mediated control of cell survival. These findings expand the p53 network to phospholipid metabolism and uncover a new molecular pathway connecting p53 to AKT signaling.

Humidification during laparoscopic surgery: overview of the clinical benefits of using humidified gas during laparoscopic surgery.

PURPOSE: The peritoneum is the serous membrane that covers the abdominal cavity and most of the intra-abdominal organs. It is a very delicate layer highly susceptible to damage and it is not designed to cope with variable conditions such as the dry and cold carbon dioxide (CO2) during laparoscopic surgery. The aim of this review was to evaluate the effects caused by insufflating dry and cold gas into the abdominal cavity after laparoscopic surgery. METHODS: A literature search using the Pubmed was carried out. Articles identified focused on the key issues of laparoscopy, peritoneum, morphology, pneumoperitoneum, humidity, body temperature, pain, recovery time, post-operative adhesions and lens fogging. RESULTS: Insufflating dry and cold CO2 into the abdomen causes peritoneal damage, post-operative pain, hypothermia and post-operative adhesions. Using humidified and warm gas prevents pain after surgery. With regard to hypothermia due to desiccation, it can be fully prevented using humidified and warm gas. Results relating to the patient recovery are still controversial. CONCLUSIONS: The use of humidified and warm insufflation gas offers a significant clinical benefit to the patient, creating a more physiologic peritoneal environment and reducing the post-operative pain and hypothermia. In animal models, although humidified and warm gas reduces post-operative adhesions, humidified gas at 32 °C reduced them even more. It is clear that humidified gas should be used during laparoscopic surgery; however, a question remains unanswered: to achieve even greater clinical benefit to the patient, at what temperature should the humidified gas be when insufflated into the abdomen? More clinical trials should be performed to resolve this query.

Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model.

PURPOSE: The addition of 4 % O2 and 10 % N2O to the CO2 pneumoperitoneum (PP), together with slight cooling and humidification (conditioning), contributes to reducing adhesions by preventing mesothelial damage. We investigated the effect of peritoneal damage during laparoscopy on tumor implantation. METHODS: In Experiment 1, different tumor cell concentrations were injected into control mice without PP and into mice with 60-min dry CO2PP (mesothelial damage). In Experiment 2, tumor cells were injected into control mice (group I) and in mice with mesothelial damage (group II). In groups III to VI, mesothelial damage was decreased by adding humidification, humidification + 10 % N2O, humidification + 10 % N2O + 4 % O2, and conditioning, respectively. RESULTS: In Experiment 1, the tumors increased with the number of cells injected and with mesothelial damage in the abdominal cavity (p = 0.018) and abdominal wall (p < 0.0001). Experiment 2 confirmed that 60 min of dry CO2PP increased the number of tumors in the abdominal cavity and wall (p = 0.026 and p = 0.003, respectively). The number of tumors was decreased in the abdominal cavity by conditioning (p = 0.030) and in the abdominal wall using humidified CO2 (p = 0.032) or conditioning (p = 0.026). CONCLUSIONS: Tumor implantation was enhanced by peritoneal damage (60 min of dry CO2PP and desiccation), but this was prevented by conditioning. If confirmed in humans, conditioning would become important for oncologic surgery.

Addition of nitrous oxide to the carbon dioxide pneumoperitoneum strongly decreases adhesion formation and the dose-dependent adhesiogenic effect of blood in a laparoscopic mouse model.

OBJECTIVE: To evaluate the effect of addition of nitrous oxide (N2O) to the carbon dioxide (CO2) pneumoperitoneum (PP) and the effect of blood, plasma, or red blood cells (RBCs) on postoperative adhesions in a laparoscopic mouse model. DESIGN: Prospective randomized controlled trial. SETTING: University laboratory research center. ANIMAL(S): BALB/c female mice. INTERVENTION(S): The effect of adding to the 60-minute CO2 PP 5%, 10%, 25%, 50%, or 100% N2O on adhesion formation was evaluated. Subsequently the effect of adding 1 mL blood, or RBCs, or plasma and the effect of adding different concentrations of blood were studied. Finally, the effect of adding 10% N2O, 4% O2, or both to the CO2 was evaluated in a control group and after addition of blood. MAIN OUTCOME MEASURE(S): Postoperative adhesions after 7 days. RESULT(S): N2O strongly reduces adhesion formation with a full effect at a concentration of 5% or 10%. Adhesions increase linearly with 0.125 mL to 1 mL blood. In both the control group and after adding blood, 10% N2O is the most effective factor in prevention of adhesions. CONCLUSION(S): N2O, from concentrations of 5% upward, strongly prevents adhesion formation. Blood, mainly the plasma, increases adhesion formation. These data extend the concept of the role of acute inflammation and support the importance of good surgical practice with little bleeding and peritoneal cavity conditioning in adhesion prevention.

Intraperitoneal temperature and desiccation during endoscopic surgery. Intraoperative humidification and cooling of the peritoneal cavity can reduce adhesions.

This study was conducted to document quantitatively the intraperitoneal temperature and desiccation during laparoscopic surgery. The temperature, relative humidity, and flow rate were measured in vitro and during laparoscopic surgery, at the entrance and at the exit of the abdomen. This permitted us to calculate desiccation for various flow rates using either dry CO(2) or CO(2) humidified with 100% relative humidity at any preset temperature between 25 and 37°C. The study showed that desiccation, both in vitro and in vivo, varies as expected with the flow rates and relative humidity while intraperitoneal temperature varies mainly with desiccation. Temperature regulation of bowels is specific and drops to the intraperitoneal temperature without affecting core body temperature. With a modified humidifier, desiccation could be eliminated while maintaining the intraperitoneal temperature between 31 to 32°C.

The impact of the learning curve on adhesion formation in a laparoscopic mouse model.

OBJECTIVE: To evaluate the impact of surgeon training on adhesion formation in a laparoscopic mouse model. Laparoscopic surgery and bowel manipulation was demonstrated to enhance postoperative adhesion formation. DESIGN: Prospective randomized, controlled trial. SETTING: University laboratory research center. ANIMAL(S): 200 BALB/c and 200 Swiss female mice. INTERVENTION(S): Adhesions were induced by opposing bipolar lesions and 60 minutes of pneumoperitoneum. Each surgeon operated on 80 mice (40 Swiss and 40 BALB/c), the only variable thus being his/her increasing experience. Some surgeons were already experienced gynecologists, others were starting their training. MAIN OUTCOME MEASURE(S): End points were the duration of surgery while performing the lesions. The adhesion formation was scored quantitatively (proportion and total) and qualitatively (extent, type, and tenacity) after 7 days. RESULT(S): With training, duration of surgery and adhesion formation decreased exponentially for all surgeons, whether experienced or not. Experienced surgeons had initially a shorter duration of surgery, less adhesion formation, and less de novo adhesions than inexperienced surgeons. CONCLUSION(S): These data suggest that laparoscopic skills improve with training, leading to a decrease in the duration of surgery and formation of adhesions. Therefore completion of a standardized learning curve should be mandatory when initiating adhesion formation studies both in laboratory or clinical setting.

Postoperative inflammation in the abdominal cavity increases adhesion formation in a laparoscopic mouse model.

OBJECTIVE: To investigate acute inflammation in the peritoneal cavity in adhesion formation. DESIGN: Prospective randomized, controlled trial. SETTING: University laboratory research center. ANIMAL(S): 9- to 10-week-old BALB/c female mice. INTERVENTION(S): In a laparoscopic mouse model, acute inflammation in the peritoneal cavity evaluated in CO(2) pneumoperitoneum enhanced adhesions, by CO(2) pneumoperitoneum plus manipulation, and in the latter group plus dexamethasone. MAIN OUTCOME MEASURE(S): Qualitative and quantitative adhesion scores and an acute inflammation score (neoangiogenesis, diapedesis, and leukocyte accumulation). RESULT(S): Adhesions at the lesion site were enhanced by the CO(2) pneumoperitoneum, further enhanced by manipulation, and decreased by the administration of dexamethasone. The acute inflammation scores (total, neoangiogenesis, diapedesis, and leukocyte accumulation) strongly correlated with the total adhesion score. Inflammation scores were similar at both the surgical lesion and the parietal peritoneum. CONCLUSION(S): Acute inflammation of the entire peritoneum cavity is an important mechanism involved in adhesion formation and enhances adhesion formation at the lesion site.

Effect of Reteplase and PAI-1 antibodies on postoperative adhesion formation in a laparoscopic mouse model.

BACKGROUND: Postoperative adhesions remain an important clinical problem, accounting for infertility, chronic pain and bowel obstruction. Its prevention is still inadequate and overall poorly understood. The aim of this study was to investigate the effect of Reteplase (a recombinant plasminogen activator, r-PA) and of PAI-1 antibodies upon adhesion formation in a laparoscopic model. METHODS: Pneumoperitoneum-enhanced adhesions were induced by performing a bipolar lesion in female BALB/c mice and by using pure and humidified CO(2) as insufflation gas for 60 min. In experiment 1, four doses of 0.125, 0.25, 0.5 and 1 mg/0.5 ml r-PA and one and two doses of 1 mg r-PA were administrated i.p. Two control groups were included, one without any treatment and the second one receiving four times 0.5 ml of saline. In experiment 2, four doses of 0, 1, 10 and 100 microg/0.5 ml r-PA were administrated i.p. In experiment 3, PAI-1 neutralising and non-neutralising antibodies were injected i.p. after performing the lesion on day 0 and days 2 and 4. Adhesions were scored after 7 days. RESULTS: Adhesion formation was less with the administration of four doses of 1 microg r-PA (proportion, p < 0.04, Wilcoxon). An increase in adhesion formation was observed when higher number of doses and amounts of r-PA were used (Proc GLM, eight groups, two variables, p = 0.05 for the amount of r-PA and p < 0.02 for the number of doses administrated). No effect was observed with the PAI-1 antibodies. CONCLUSIONS: Low-dose i.p. administration of rPA is effective in the prevention of adhesions in a laparoscopic mouse model.