Mast cells facilitate local VEGF release as an early event in the pathogenesis of postoperative peritoneal adhesions

BACKGROUND: Peritoneal injury sustained at laparotomy may evoke local inflammatory responses that result in adhesion formation. Peritoneal mast cells are likely to initiate this process, whereas vascular permeability/endothelial growth factor (VEGF) may facilitate the degree to which subsequent adhesion formation occurs. METHODS: Mast cell deficient mice (WBB6F1-/-), along with their mast cell sufficient counterparts (WBB6F1+/+), underwent a standardized adhesion-inducing operation (AIS) with subsequent sacrifice and adhesion assessment 14 days later in a blinded fashion. Additional CD-1 and WBB6F1+/+, and WBB6F1-/- mice were killed 2, 6, 12, and 24 hours after operation for measurement of VEGF by ELISA in systemic serum and peritoneal lavage fluid. Two further groups of CD-1 mice underwent AIS and received either a single perioperative dose of anti-VEGF monoclonal antibody (10 mug/mouse) or a similar volume of IgG isotypic antibody and adhesion formation 2 weeks later was evaluated. RESULTS: WBB6F1-/- mice had less adhesions then did their WBB6F1+/+ counterparts (median [interquartile range] adhesion score 3[3-3] vs 1.5[1-2] respectively; P < .003). Local VEGF release peaked 6 hours after AIS in both WBB6F1+/+ and CD-1 mice whereas levels remained at baseline in WBB6F1-/- mice. CD-1 mice treated with a single dose of anti-VEGF therapy during operation had less adhesions than controls (2[1.25-2] vs 3[2.25-3], P = .0002). CONCLUSIONS: Mast cells and VEGF are central to the formation of postoperative intra-abdominal adhesions with mast cells being responsible, either directly or indirectly, for VEGF release into the peritoneal cavity after operation. In tandem with the recent clinical success of anti-VEGF monoclonal antibodies in oncologic practice, our observations suggest an intriguing avenue for research and development of anti-adhesion strategy.     

Development of peritoneal adhesions in macrophage depleted mice

BACKGROUND: We present a new mouse model for the study of peritoneal adhesions using macrophage Fas-induced apoptosis (Mafia) transgenic mice expressing a Fas-FKBP construct under control of the murine c-fms promoter. Mafia mice allow systemic macrophage depletion by dimerization of Fas with a synthetic dimerizer, AP20187. Results demonstrate that macrophage depletion in Mafia mice induces peritoneal adhesion formation when the peritoneal cavity is also exposed to an irritant. The Mafia mouse model presents a reproducible, non-surgical approach for research in adhesion formation and prevention. MATERIALS AND METHODS: Mafia mice were treated with AP20187 using an intravenous (i.v.) or intraperitoneal (i.p.) injection. Control groups included mock-treated Mafia mice and both AP20187 and mock-treated wild type mice. Seven days after treatment, mice were observed for the presence of adhesions. RESULTS: After i.p. injection with AP20187, 76% of Mafia mice developed adhesions whereas none of the mock-treated Mafia or wild-type mice developed adhesions, and only one AP20187-treated wild-type mouse (5.8%) developed a mild adhesion. Mafia mice treated with AP20187 i.v. exhibited macrophage depletion not significantly different than i.p. treated mice, but did not develop adhesions. In contrast, Mafia mice treated with AP20187 i.v. developed adhesions when diluent was also injected into the peritoneal cavity, whereas i.p diluent alone had no effect. CONCLUSION: Macrophage depletion, combined with a peritoneal irritant, results in peritoneal adhesion formation in transgenic Mafia mice. Macrophages appear to play a protective role in the development and/or repair of peritoneal adhesions.     

Intraperitoneal transplantation of isologous mesothelial cells for prevention of adhesions.

OBJECTIVE: To study the effect of transplantation of mesothelial cells on the formation of adhesions after peritoneal abrasion. DESIGN: Animal study. SETTING: Teaching hospital, Germany. ANIMALS: 30 isologous eight-week old Lewis rats to allow for harvesting of the greater omentum from a separate group. INTERVENTIONS: The first group (n = 10) served as mesothelial cell donors. The other animals had laparotomy and induction of adhesions by standardised abrasion of the peritoneum. The trial group (n = 10) were given a suspension of 10(6) mesothelial cells/100 g body weight intraperitoneally and the control group (n = 10) an equal volume of culture medium. After 10 days the animals were killed. MAIN OUTCOME MEASURES: Measurements of the areas of adhesions by computer aided morphometry. RESULTS: The trial group developed a mean (SD) adhesion area of 122.7 (176.7) mm2, and the controls 310.5 (179.1) mm2. The corresponding medians (range) were 51.2 (0-547.1) and 274.3 (100.6-575.4). Transplantation of mesothelial cells resulted in a significant reduction in adhesion formation (Wilcoxon test, p<0.01). CONCLUSION: Intraperitoneal transplantation of mesothelial cells is an effective way of reducing the formation of adhesions.     

Hyaluronan-based antiadhesive membrane has no major effect on intraperitoneal growth of colonic tumour cells

BACKGROUND: A relationship between post-surgical adhesion formation and peritoneal tumour implantation has been proposed. Hyaluronan (HA)-based agents reduce adhesion formation, but the effect on peritoneal tumour is not established. This study investigated the influence of a HA-containing agent on intraperitoneal tumour in an experimental model. METHODS: 66 Balb/c mice underwent laparotomy and damage was inflicted to the parietal peritoneum. The animals were randomized into five groups. Groups 1 and 2 received HA-carboxymethylcellulose bioresorbable membrane and no treatment, respectively. Mice in groups 3-5 were injected intraperitoneally with 10(5) colon 26-B cells after the laparotomy. Treatment consisted of HA membrane, no HA agent and placement of HA membrane on the non-traumatized peritoneal wall, respectively. Animals were killed after 14 days; adhesions were scored in groups 1 and 2, and the tumour mass in groups 3-5. 45 Wag/Rij rats underwent the same procedures and treatment as mice in groups 3-5. In rats, 10(6) CC-531 cells were injected. Rats were killed after 3 weeks and the tumour mass was scored. Results: HA membrane resulted in a significant reduction of adhesions, but had no major effect on the intraperitoneal tumour mass in mice and rats. CONCLUSION: HA-carboxymethylcellulose bioresorbable membrane has no major effect on intraperitoneal tumour implantation and growth in an experimental model.     

Role of mast cells and myofibroblasts in human peritoneal adhesion formation

OBJECTIVE: To study fibroblasts and mast cells in human peritoneal adhesions and to evaluate whether their interaction plays a role in adhesion development. SUMMARY BACKGROUND DATA: Myofibroblasts play a critical role in wound repair/fibrosis. Mast cells influence the formation of peritoneal adhesions in a rat model, and they are modulators of fibroblast functions. METHODS: Peritoneal adhesion biopsies were processed for either histology (H&E, toluidine blue) or immunohistochemistry (tryptase, laminin, collagen type IV and VIII, and alpha-SMA) or grown as explants for obtention of fibroblasts. The effects of mast cell (HMC-1) sonicate and selected mast cell mediators and cytokines on fibroblast proliferation ([ (3)H]thymidine) and collagen synthesis ([ (3)H]proline) and on fibroblast contractile activity (tridimensional collagen lattice) were evaluated. Mast cell mediators influencing fibroblast proliferation were partially characterized by enzymatic susceptibility and FPLC gel filtration column chromatography. RESULTS: Most of the fibroblasts in peritoneal adhesions were identified as alpha-SMA-positive myofibroblasts. Mast cell hyperplasia was observed and more than one third of the mast cells were degranulated. Few mast cells showed a faint staining for laminin or collagen type IV and VIII. Mast cell sonicate increased fibroblast proliferation and contractile activity while decreasing collagen synthesis. Mast cell sonicate proliferating activities were found to be proteinase-sensitive with a molecular weight of more than 158 kd, of approximately 40 kd, and of less than 10 kd. TGF-beta and tryptase enhanced collagen synthesis; TNF-alpha and chymase decreased it. None of the selected mediators increased fibroblast proliferation. CONCLUSIONS: Myofibroblasts are the main connective tissue cells present in human peritoneal adhesions, and mast cells play a direct role in peritoneal adhesion formation.     

Experimental adhesion prophylaxis with recombinant tissue plasminogen activator.

The deposition of fibrin in the peritoneal cavity leads to fibrous adhesion formation. Recombinant tissue plasminogen activator (rtPA), delivered locally, was investigated as a method of preventing adhesion formation. Six standardised areas of peritoneal ischaemia were formed in each of 36 male Wistar rats randomised to three intraperitoneal treatments: (A) no treatment control; (B) carboxymethylcellulose gel; (C) rtPA-carboxymethylcellulose gel combination. At 1 week all animals underwent relaparotomy and the number of ischaemic sites with an adhesion counted by an independent observer. rtPA-treated animals formed fewer adhesions compared with gel alone or controls (median number of adhesions 1.5 versus 2.5 versus 5, P < 0.001, ANOVA). Intraperitoneal rtPA in a slow-release formulation is able to reduce adhesion formation significantly in an animal model and may prove to have clinical benefit.     

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.     

Intraperitoneal adhesions after open or laparoscopic abdominal procedure: an experimental study in the rat

Abstract Background: Adhesion formation is common after abdominal surgery. The incidence and severity of adhesion formation following open or laparoscopic surgery remain controversial. The role of CO(2) pneumoperitoneum is also widely discussed. This study aimed to compare adhesion formation following peritoneal injury by electrocoagulation performed through open or laparoscopic procedures in a rat model. Materials and Methods: Sixty male rats were randomized to undergo a 1.5-cm peritoneal injury with unipolar cautery under general anesthesia: open surgery (Group A, n=20), laparoscopic surgery with CO(2) pneumoperitoneum (Group B, n=20), and laparoscopic surgery with air pneumoperitoneum (Group C, n=20). Duration of the procedures was fixed at 90 minutes in all groups, and pneumoperitoneum pressure was kept at 10?mm Hg. Ten days later, the animals underwent a secondary laparotomy to score peritoneal adhesions using qualitative and quantitative parameters. Results: Forty-five rats developed at least one adhesion: 95% in Group A, 83% in Group B, and 55% in Group C (P<.01; Group C versus Group A, P<.01). According to number, thickness, tenacity, vascularization, extent, type, and grading according to the Zühkle classification, no significant difference was observed between Groups A and B. The distribution of adhesions after open surgery was significantly different than after laparoscopic surgery (P<.001). It is interesting that Group C rats developed significantly fewer adhesions at the traumatized site, and their adhesions had less severe qualitative scores compared with those after open surgery (P<.01). Conclusions: In this animal model, CO(2) laparoscopic surgery did not decrease the formation of postoperative adhesion, compared with open surgery. The difference with the animals operated on with air pneumoperitoneum emphasizes the role of CO(2) in peritoneal injury leading to adhesion formation.     

Endotoxin tolerance from lipopolysaccharide pretreatment induces nuclear factor-kappaB alterations not present in C3H/HeJ mice

BACKGROUND: Lipopolysaccharide (LPS) activation of macrophage (MO) cytokine secretion requires activation and translocation of nuclear factor-kappaB (NF-kappaB). Endotoxin tolerance induced in LPS-responsive C3H/HeN MOs by LPS pretreatment results in decreased tumor necrosis factor (TNF) secretion and altered NF-kappaB activation. C3H/HeJ MOs have a genetic defect that renders them tolerant to LPS activation. We hypothesized that the alterations of NF-kappaB activation seen with LPS tolerance in HeN MOs would be present in HeJ mice. METHODS: MOs from C3H/HeJ and C3H/HeN mice were cultured with +/- 10 ng/mL LPS pretreatment for 24 hours and then stimulated with 1 to 1,000 ng/mL LPS. Activation of NF-kappaB was assayed by gel shift using a 32P-labeled specific oligonucleotide 30 minutes after LPS activation. TNF secretion 6 hours after LPS stimulation was measured by bioassay. RESULTS: LPS stimulation activated NF-kappaB in both HeN and HeJ MOs. We observed decreased NF-kappaB activation and a characteristic mobility shift in endotoxin-tolerant MOs from HeN mice that were not present in HeJ MOs. In contrast with the results in HeN mice, LPS pretreatment did not induce any alterations in NF-kappaB activation in HeJ MOs. LPS-stimulated TNF secretion was decreased in HeN MOs after LPS pretreatment. There was no change in TNF secretion in HeJ MOs, but, overall, TNF secretion by these cells was much less than that seen in HeN cells. CONCLUSION: MOs from C3H/HeN mice rendered LPS-tolerant by low-dose LPS pretreatment have alterations in activation of NF-kappaB not present in LPS-hyporesponsive C3H/HeJ mice.     

Expression of transforming growth factor beta1 in patients with and without previous abdominal surgery

HYPOTHESIS: Transforming growth factor beta1 (TGF-beta1) plays an important role in the formation of adhesions after abdominal operations. DESIGN: Prospective, observational study. SETTING: University-based, tertiary referral center. PATIENTS: Patients undergoing elective open abdominal operations were recruited and divided into 2 groups. Twenty-two patients with a history of abdominal surgery were designated as study patients, and 10 patients with no history of abdominal surgery served as controls. INTERVENTIONS: Samples of normal peritoneum, peritoneal scar tissues, and serum were obtained from all patients at the time of surgery. MAIN OUTCOME MEASURES: Samples were assayed for total TGF-beta1 expression using an enzyme-linked immunosorbent assay. RESULTS: Scar tissues expressed significantly greater amounts of TGF-beta1 (0.47 pg/ micro L) compared with normal peritoneal tissue from both study patients (0.29 pg/ micro L; P =.03) and controls (0.17 pg/ micro L; P =.002). Serum TGF-beta1 levels were also higher in study patients (1.71 pg/ micro L) compared with controls (1.22 pg/ micro L; P =.02). Neither adhesion nor serum TGF-beta1 expression correlated with time since last operation, total number of previous operations, or severity of intra-abdominal adhesions. CONCLUSION: These results suggest that TGF-beta1 may play an important role in human peritoneal adhesion formation.     

The effect of tenoxicam on intraperitoneal adhesions and prostaglandin E2 levels in mice

We determined whether tenoxicam administered intraperitoneally in the preoperative period had an effect on the development of postoperative intraabdominal adhesions (IAA). For this purpose, 100 albino mice were divided into four random groups. Mice in Group 1 were given only 1 mL of 0.9% NaCl intraperitoneally, whereas in Group 2, 1 mL of tenoxicam (150 microg = 5 mg/kg) was administered. After the induction of anesthesia, a median laparotomy was performed, and the bowels were traumatized by touching them with powdered gloves before the incision was closed in Groups 3 and 4. Intraperitoneal tenoxicam was administered to mice in Group 4 after skin closure. All mice were killed after 14 days to determine macroscopic and microscopic IAA; prostaglandin E2 levels were also measured. Postoperative evaluation revealed a reduced IAA formation and a parallel decrease in tissue prostaglandin E2 levels in Group 1 and 2 mice. We conclude that intraperitoneal tenoxicam decreased IAA formation with no peritoneal reaction in the postoperative period. Implications: Postoperative intraabdominal adhesions can cause intestinal obstruction, pelvic pain, or infertility. In this study, we showed that intraperitoneally administered tenoxicam decreases tissue prostaglandin E2 levels and intraabdominal adhesions in mice.     

Overproduction of transforming growth factor-beta1 (TGF-beta1) is associated with adhesion formation and peritoneal fibrinolytic impairment

BACKGROUND: Reduction in peritoneal fibrinolytic capacity and increased transforming growth factor-beta1 (TGF-beta1) production are associated with adhesion development. This study investigated the expression of TGF-beta1 in peritoneal tissue, and possible correlation with components of the fibrinolytic system locally in peritoneal tissue. MATERIALS AND METHODS: Peritoneal samples were taken from 22 patients at relaparotomy. Samples of adhesions were collected from 10 patients. The patients were categorized into different groups depending on the quantity and the quality of adhesions. TGF-beta1 and components of the fibrinolytic system in tissue extracts were assayed using enzyme-linked immunosorbent assays. RESULTS: The concentration of active TGF-beta1 in peritoneal samples from patients with extensive adhesions was double (P <.01) that of healthy subjects, but the total levels of TGF-beta1 were similar (P =.63). In adhesion tissue, both active (P <.003) and total (P <.008) TGF-beta1 concentrations were more than twice as high as unaffected peritoneum. There was a significant correlation between the concentration of plasminogen activator inhibitor type 1 in peritoneal samples with active TGF-beta1 (P <.03, r = 0.693) and adhesion tissue with total TGF-beta1 (P =.001, r = 0.872). The other components of the fibrinolytic system did not correlate significantly with TGF-beta1. CONCLUSIONS: These data indicate that an overexpression of TGF-beta1 is associated with adhesion formation, possibly through a mechanism involving local regulation of plasminogen activator inhibitor type 1.     

The neurokinin 1 receptor regulates peritoneal fibrinolytic activity and postoperative adhesion formation

Background

Intra-abdominal adhesions are a common source of postoperative morbidity. Previous studies in our laboratory have shown that a neurokinin 1 receptor antagonist (NK-1RA) reduces abdominal adhesion formation and increases peritoneal fibrinolytic activity. However, the cellular pathway by which the antagonist exerts its effects is unclear, as cultured peritoneal mesothelial cells exposed to the NK-1RA show increases in fibrinolytic activity despite having very low expression of neurokinin 1 receptor (NK-1R) messenger RNA and protein. Our aim was to determine whether the NK-1R plays an essential role in the adhesion-reducing effects of the NK-1RA, or if the NK-1RA is acting independently of the receptor.

Methods

Homozygous NK-1R knockout mice and age matched wild-type mice underwent laparotomy with cecal cautery to induce adhesions. At the time of surgery, mice received a single intraperitoneal dose of either NK-1RA (25 mg/kg) or saline alone. Adhesion severity at the site of cecal cautery was assessed on postoperative day 7. In a separate experiment, peritoneal fluid was collected from wild type and NK-1R knockout mice 24 h after laparotomy with cecal cautery and administration of either NK-1RA or saline. Tissue plasminogen activator levels, representative of total fibrinolytic activity, were then measured in peritoneal fluid.

Results

In wild-type mice, NK-1RA administration significantly decreased adhesion formation compared with saline controls. Among the NK-1R knockout mice, there was no significant reduction in adhesion formation by the NK-1RA. Fibrinolytic activity increased 244% in wild-type mice administered NK-1RA compared with saline controls; however, the NK-1RA did not raise fibrinolytic activity above saline controls in NK-1R knockout mice.

Conclusions

These data indicate that the NK-1R mediates the adhesion-reducing effects of the NK-1RA, in part, by the upregulation of peritoneal fibrinolysis, and suggest that the NK-1R is a promising therapeutic target for adhesion prevention.     

SPRAY OF PHOSPHOLIPID POWDER REDUCES PERITONEAL ADHESIONS IN RABBITS

Background : The possible effects of peritoneal dialysis and a combination of two exogenous phospholipids, dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG), on experimentally induced intraperitoneal adhesion formation in rabbits were compared. Methods : Fifty New Zealand rabbits equally divided in five groups underwent a midline laparotomy to create a right iliac fossa 5 × 1 cm parietal peritoneal defect and a matching defect over the adjacent large bowel. In 10 control rabbits (group I) the abdominal wound was closed without any further intervention. Twenty rabbits forming groups II and III underwent two sessions of peritoneal dialysis, one following abdominal closure and the second 24 h later, through a catheter placed at surgery. Rabbits in group III received an intraperitoneal injection of DPPC and PG after each session of dialysis. In 10 animals (group IV) a DPPC gel was applied to the defect over the large bowel and in 10 animals (group V) the peritoneal cavity was sprayed with a ‘puff’ of DPPC:PG (7:3) powder prior to abdominal closure. All the animals were killed a week after the laparotomy to assess the extent of adhesion formation. Results : The formation of adhesions was reduced in all the groups compared to the controls but a statistically significant difference was observed only in the group receiving the intraperitoneal ‘puff’ of DPPC:PG powder. Conclusion : A combination of DPPC and PG sprayed as a ‘puff’ intraperitoneally reduces experimentally induced peritoneal adhesions in rabbits.     

Spray of phospholipid powder reduces peritoneal adhesions in rabbits.

BACKGROUND: The possible effects of peritoneal dialysis and a combination of two exogenous phospholipids, dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG), on experimentally induced intraperitoneal adhesion formation in rabbits were compared. METHODS: Fifty New Zealand rabbits equally divided in five groups underwent a midline laparotomy to create a right iliac fossa 5 x 1 cm parietal peritoneal defect and a matching defect over the adjacent large bowel. In 10 control rabbits (group I) the abdominal wound was closed without any further intervention. Twenty rabbits forming groups II and III underwent two sessions of peritoneal dialysis, one following abdominal closure and the second 24 h later, through a catheter placed at surgery. Rabbits in group III received an intraperitoneal injection of DPPC and PG after each session of dialysis. In 10 animals (group IV) a DPPC gel was applied to the defect over the large bowel and in 10 animals (group V) the peritoneal cavity was sprayed with a 'puff of DPPC:PG (7:3) powder prior to abdominal closure. All the animals were killed a week after the laparotomy to assess the extent of adhesion formation. RESULTS: The formation of adhesions was reduced in all the groups compared to the controls but a statistically significant difference was observed only in the group receiving the intraperitoneal 'puff' of DPPC:PG powder. CONCLUSION: A combination of DPPC and PG sprayed as a 'puff' intraperitoneally reduces experimentally induced peritoneal adhesions in rabbits.     

Surgical glove powder and intraperitoneal adhesion formation. An appeal for the use of powder-free surgical gloves.

Intraperitoneal adhesion formation is a major cause of infertility and/or intestinal obstruction. Among the many well-known aetiological factors responsible for peritoneal inflammatory reaction is surgical glove powder; for example, cornstarch powder. A study was undertaken on 30 rats to determine whether cornstarch powder caused intraperitoneal adhesions. The rats were randomised into two groups under laboratory conditions. Laparotomies were performed on all the rats and trauma inflicted to the right uterine horn. The study group received cornstarch powder suspended in normal physiological salt solution intraperitoneally, and the control group received only normal physiological salt solution. Peritoneal adhesions were evaluated after 2 weeks and statistically analysed with a t-test and 95% confidence intervals. The study group showed a statistically significantly higher incidence of intraperitoneal adhesions (P = 0.0003). It is concluded that cornstarch, as used on surgical gloves, caused peritoneal adhesions and should therefore be removed before surgery. Powder-free gloves are more suitable for preventing adhesion formation.     

Ibuprofen inhibition of postsurgical adhesion formation: A time and dose response biochemical evaluation in rabbits

Recently, a reduction in postoperative adhesion formation in rabbits which received high-dose ibuprofen (280 mg/kg/day) treatment in the perioperative interval was reported. Because these results could have resulted from a nonspecific effect of ibuprofen, the effects of ibuprofen on peritoneal injury in a time and dose response fashion was evaluated. Seventy rabbits were assigned to seven groups. All rabbits received a dose of ibuprofen 1 hr prior to surgery. The time of the second dose was either 8 or 12 hr after the surgical procedure; 8 hr for groups A, C, and E; 12 hr for groups B, D, and F (A, B: 70 mg/ kg; C, D: 35 mg/kg; E, F: 17.5 mg/kg, respectively). Thereafter, rabbits received further dosing every 6 hr to complete a total 10-dose regimen. Group G served as a nontreatment control. Surgical injury was induced by either abrasion or ischemia of the right uterine horn. Immediately after closing the incision, 10 μCi of ¹⁴C-labeled glucosamine and 10 μCi of ¹⁴C-labeled proline were injected into each rabbit. All rabbits underwent a second laparotomy on the fifth postoperative day for evaluation of adhesion formation. Uterine tissue adjacent to the site of uterine healing was excised for determination of glycosaminoglycan and collagen concentration. In the nontreatment control group G, 5 of the 10 rabbits had severe grade 2 adhesions at the time of second laparotomy, 3 had grade 1 filmy adhesions, and 2 had no adhesions. This is in marked contrast (P < 0.025) to the group that received ibuprofen at 70 mg/kg/day with the first postoperative dose 8 hr after surgery (group A). In this group, no rabbits had severe grade 2 adhesions, 3 rabbits had filmy grade 1 adhesions, and 7 rabbits were free of pelvic adhesions. A gradual tendency towards more adhesions and more severe adhesions was apparent in groups B-F as the dose of ibuprofen was decreased and the time of first postoperative injection was prolonged. The recovery of ¹⁴C-labeled glucosamine from the glycosaminoglycan extraction demonstrated a positive correlation between the cpm recovered and the severity of adhesions formed. Groups A and B had, overall, the lowest ratios of glucosamine (1.47 ± 0.08 and 1.56 ± 0.09, respectively) which were statistically different from the nontreatment control group G (1.76 ± 0.11, P < 0.05). There was also a positive correlation between the formation of severe adhesions and the ratio of ¹⁴C-labeled proline recovered by collagen extraction. Those rabbits which did not develop adhesions had an average collagen ratio of 1.48 ± 0.03; those with grade 1, filmy adhesions, 1.68 ± 0.04; those with grade 2 adhesions, 1.89 ± 0.04 (P < 0.05 for all treatment vs control groups). Rabbits undergoing either abrasion or devascularization procedures of their uterine horn manifested a significant reduction in peritoneal adhesion formation with perioperative ibuprofen treatment. Further, a positive correlation existed between the formation of glycosaminoglycans and collagen in the site of uterine healing and the subsequent formation of adhesions.     

Association between the expression of mast cell chymase and intraperitoneal adhesion formation in mice

BACKGROUND: Adhesion formation is a major source of postoperative morbidity and mortality. Mast cells and their major protease, chymase, have been shown to participate in the healing process as well as in tissue remodeling. We aimed to identify the role of mast cells in intraperitoneal adhesion formation and to assess whether there is an association between the expression of mast cell chymase and adhesion formation. MATERIALS AND METHODS: Both mast cell-deficient W/W(V) mice and congenic +/+ mice received a standardized lesion produced by cecal scraping and the application of 95% ethanol. Adhesions were assessed blindly 1 week later using a standardized scale. In addition, histamine content, mast cell numbers, and chymase activity in cecum as well as at the healing sites were evaluated before and 7 days after surgical injury. RESULTS: A significant reduction in adhesion formation was seen in mast cell-deficient W/W(V) mice (P < 0.05). In the normal cecum, histamine content did not significantly differ between W/W(V) and +/+ mice. Chymase activity in cecum was detected in control +/+ mice, but not in W/W(V) mice. Mast cell numbers and chymase activity levels at the healing sites of +/+ mice were significantly increased 7 days after surgery. CONCLUSIONS: Our results indicate that mast cells contribute to intraperitoneal adhesion formation in mice, and suggest that chymase originating from mast cells is important in the development of adhesions.     

Phosphatidylcholine prevents postoperative peritoneal adhesions: an experimental study in the rat

Phosphatidylcholine (PC) is the main constituent of the surface-active material coating peritoneal mesothelium. It may prevent postoperative adhesion formation through production of a lubricant film on mesothelial defects. We therefore examined the effect of its soluble form on surgically induced intraabdominal adhesions in rats. The adhesions were induced at laparotomy by any of four different operative models. PC was administered intraperitoneally (20 mg/rat) or intravenously (20 mg/rat or 50 mg/rat) at the end of the operation and on the second and third postoperative day. It was found that the degree of postoperative adhesion formation was significantly reduced by the intraperitoneal injection of PC in all 4 models. In contrast, no effect was achieved by the intravenous injection of PC, not even at a very high dose level. Our results suggest that soluble PC administered intraperitoneally might be a potent adjunct in postoperative adhesion prevention.     

A kinetic analysis of peritoneal fluid cytology and arachidonic acid metabolism after abrasion and reabrasion of rabbit peritoneum

The purpose of this study was to investigate the cellular composition of peritoneal fluid during post-surgical re-epithelialization and to determine the metabolism of arachidonic acid by these cells. Rabbits underwent a midline laparotomy followed by abrasion of the broad ligament. The presence of adhesions was graded and the peritoneal exudative cells collected up to 14 days thereafter. Ascitic fluid and cells were separated by centrifugation and the cellular percipitate incubated with [14C]arachidonic acid. The aliquot was separated by silica Gel G thin-layer chromatography and the specific radioactivity of each strip determined. To evaluate the reformation of adhesions 14 days after the first abrasion, rabbits underwent reabrasion of the same area and the pattern of arachidonic acid metabolism by the ascites cells was similarly evaluated. Six hours after the abrasion, PMNs comprised 87.5% of the peritoneal exudative cells (total 0.03 X 10(7) cells/rabbit). On Day 3, the total cell number increased to 2.92 X 10(7), 97.6% of which were large mononuclear cells. No significant change in the type of distribution of adhesions was evident from 6 hr through Day 2. After Day 7, the total number of adhesions was minimal; however, those that were present were primarily severe. The second-look evaluation of adhesion formation was not found to be consistent prior to the 7th postoperative day, since many filmy bands present prior to that time were not present later. The in vitro formation of 5-HETE by these cells increased from 6 hr through Day 11. Production of di-HETE increased beginning Day 3 and maintained high steady state levels thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)