The mitogenic activity of peritoneal tissue repair cells: control by growth factors

The effects of tumor-derived supernatants (TDS) on cancer cell progression: A review and update on carcinogenesis and immunotherapy

Tumors can produce bioactive substances called tumor-derived supernatants (TDS) that modify the immune response in the host body. This can result in immunosuppressive effects that promote the growth and spread of cancer. During tumorigenesis, the exudation of these substances can disrupt the function of immune sentinels in the host and reinforce the support for cancer cell growth. Tumor cells produce cytokines, growth factors, and proteins, which contribute to the progression of the tumor and the formation of premetastatic niches. By understanding how cancer cells influence the host immune system through the secretion of these factors, we can gain new insights into cancer diagnosis and therapy.

Dehydrated Human Amniotic-Chorionic Membrane Reduces Incisional Hernia Formation in an Animal Model

BACKGROUND

Currently there are no standard of care treatment strategies for IH prevention (IHP). Dehydrated human amnion-chorion (dHACM) is a healing adjunct that elutes growth factors including several that have reduced IH in animal models. We therefore performed a double-blinded, prospective randomized controlled trial (RCT) to test the hypothesis that dHACM significantly reduces IH formation in a well-studied animal model of acute IH.

MATERIAL AND METHODS

Forty 16-week-old male Sprague-Dawley rats were randomized to one of four groups: No Treatment vs. dHACM Sheet (Group A), and Saline vs. dHACM Injection (Group B). Each animal underwent a 5-cm midline laparotomy which was incompletely closed with 5-0 plain gut sutures; this was performed by a surgeon blinded to treatment group (first blind). After 28 days, the primary endpoints of IH formation and hernia size were determined by study staff blinded to treatment (second blind). Secondary endpoints included healed fascia tensile strength as determined by tensiometry, systemic and local inflammatory markers as measured by ELISA, and fascial scar collagen I/III ratios per Western blotting.

RESULTS

In Group A, No Treatment developed IH at 87.5% vs. 62.5% for Sheet (P = 0.28). Hernias that formed in the Sheet group were significantly smaller (P = 0.036). In Group B, Injection and Saline yielded identical IH rates of 77.8%. Molecular characterization of fascial scar demonstrated non-inferior tensile strength, collagen I/III ratios, and inflammatory markers in dHACM-treated animals.

CONCLUSIONS

dHACM sheets significantly reduced the size of IH following laparotomy when compared to no treatment.

Post-Surgical Peritoneal Scarring and Key Molecular Mechanisms

Post-surgical adhesions are internal scar tissue and a major health and economic burden. Adhesions affect and involve the peritoneal lining of the abdominal cavity, which consists of a continuous mesothelial covering of the cavity wall and majority of internal organs. Our understanding of the full pathophysiology of adhesion formation is limited by the fact that the mechanisms regulating normal serosal repair and regeneration of the mesothelial layer are still being elucidated. Emerging evidence suggests that mesothelial cells do not simply form a passive barrier but perform a wide range of important regulatory functions including maintaining a healthy peritoneal homeostasis as well as orchestrating events leading to normal repair or pathological outcomes following injury. Here, we summarise recent advances in our understanding of serosal repair and adhesion formation with an emphasis on molecular mechanisms and novel gene expression signatures associated with these processes. We discuss changes in mesothelial biomolecular marker expression during peritoneal development, which may help, in part, to explain findings in adults from lineage tracing studies using experimental adhesion models. Lastly, we highlight examples of where local tissue specialisation may determine a particular response of peritoneal cells to injury.

Role of fibroblast growth factors in organ regeneration and repair

In its broad sense, regeneration refers to the renewal of lost cells, tissues or organs as part of the normal life cycle (skin, hair, endometrium etc.) or as part of an adaptive mechanism that organisms have developed throughout evolution. For example, worms, starfish and amphibians have developed remarkable regenerative capabilities allowing them to voluntarily shed body parts, in a process called autotomy, only to replace the lost parts afterwards. The bizarre myth of the fireproof homicidal salamander that can survive fire and poison apple trees has persisted until the 20th century. Salamanders possess one of the most robust regenerative machineries in vertebrates and attempting to draw lessons from limb regeneration in these animals and extrapolate the knowledge to mammals is a never-ending endeavor. Fibroblast growth factors are potent morphogens and mitogens that are highly conserved among the animal kingdom. These growth factors play key roles in organogenesis during embryonic development as well as homeostatic balance during postnatal life. In this review, we provide a summary about the current knowledge regarding the involvement of fibroblast growth factor signaling in organ regeneration and repair. We also shed light on the use of these growth factors in previous and current clinical trials in a wide array of human diseases.

Gastric cancer cell supernatant causes apoptosis and fibrosis in the peritoneal tissues and results in an environment favorable to peritoneal metastases, in vitro and in vivo

Background

In this study, we examined effects of soluble factors released by gastric cancer cells on peritoneal mesothelial cells in vitro and in vivo.

Methods

HMrSV5, a human peritoneal mesothelial cell line, was incubated with supernatants from gastric cancer cells. Morphological changes of HMrSV5 cells were observed. Apoptosis of HMrSV5 cells was observed under a transmission electron microscope and quantitatively determined by MTT assay and flow cytometry. Expressions of apoptosis-related proteins (caspase-3, caspase-8, Bax, bcl-2) were immunochemically evaluated.

Results

Conspicuous morphological changes indicating apoptosis were observed in HMrSV5 cells 24 h after treatment with the supernatants of gastric cancer cells. In vivo, peritoneal tissues treated with gastric cancer cell supernatant were substantially thickened and contained extensive fibrosis.

Conclusions

These findings demonstrate that supernatants of gastric cancer cells can induce apoptosis and fibrosis in HMrSV5 human peritoneal mesothelial cells through supernatants in the early peritoneal metastasis, in a time-dependent manner, and indicate that soluble factors in the peritoneal cavity affect the morphology and function of mesothelial cells so that the resulting environment can become favorable to peritoneal metastases.

Internal hernias after abdominal surgeries: MDCT features

As less-invasive treatments for small bowel obstruction, such as laparoscopic surgery or small incision therapy, have become common, there is a growing demand for preoperative assessment of the cause and location of the small bowel obstruction. Thus, the role of computed tomography (CT) in the evaluation of small bowel obstruction is expanding. CT imaging of internal hernias (IHs) has been extensively described and is well established; however, CT imaging of IH after abdominal surgeries is not well recognized because of their anatomical complexity. The aims of this pictorial review are (1) to evaluate the causes of internal IHs in relation to previous abdominal surgery (e.g., IH associated with Roux-en-Y reconstruction, Billroth II reconstruction, peritoneal adhesive band, perineal hernia, and IH after gynecological procedures), (2) to demonstrate the spectrum of imaging findings on multidetector CT (MDCT), and (3) explain the key features for CT diagnosis of IHs related to previous surgical procedures, with emphasis on the multi-planar reformation (MPR) image. We also demonstrate the dynamic changes in the progression of mesenteric strangulation revealed by CT. Understanding the imaging appearance on MDCT can help radiologists guide therapy for patients with a small bowel obstruction after abdominal surgery.

Sunitinib inhibits postoperative adhesions in a rabbit model

BACKGROUND

Postoperative abdominal adhesions are a major cause of morbidity and mortality. We previously demonstrated the inhibitory effect of sunitinib, a receptor tyrosine kinase inhibitor, on adhesion formation in a murine model, and now investigate its effects in a rabbit model.

METHODS

Forty New Zealand White rabbits underwent a standard adhesion procedure. Preoperatively, animals were randomized to treatment with sunitinib or saline (control). Animals were treated with a total of 11 daily doses, 1 preoperative and 10 postoperative. One group of 20 animals (group 1) was humanely killed on postoperative day 10, and the other (group 2) on postoperative day 30. After killing, adhesions were scored and abdominal wounds were collected for tensile strength and microvessel density measurements.

RESULTS

Sunitinib-treated animals in group 1 had a mean tenacity score of 1.67 ± 0.29 compared with 3.60 ± 0.16 in control animals (P < .01). Similarly, the mean tenacity scores for sunitinib-treated and control animals in group 2 were 0.20 ± 0.20 and 2.70 ± 0.37, respectively (P < .01). The mean uterine involvement scores for sunitinib-treated and control animals in group 1 were 1.44 ± 0.29 and 3.70 ± 0.15, respectively (P < .01), and in group 2 were 0.10 ± 0.10 and 2.70 ± 0.45, respectively (P < .01). There were no differences in ultimate or modular wound tensile strength between sunitinib-treated and control animals.

CONCLUSION

Sunitinib significantly reduces postoperative adhesions in a rabbit model. This therapy may improve postoperative adhesion-related morbidity and mortality.

Peritoneal damage: the inflammatory response and clinical implications of the neuro-immuno-humoral axis

BACKGROUND

The peritoneum is a bilayer serous membrane that lines the abdominal cavity. We present a review of peritoneal structure and physiology, with a focus on the peritoneal inflammatory response to surgical injury and its clinical implications.

METHODS

We conducted a nonsystematic clinical review. A search of the Ovid MEDLINE database from 1950 through January 2009 was performed using the following search terms: peritoneum, adhesions, cytokine, inflammation, and surgery.

RESULTS

The peritoneum is a metabolically active organ, responding to insult through a complex array of immunologic and inflammatory cascades. This response increases with the duration and extent of injury and is central to the concept of surgical stress, manifesting via a combination of systemic effects, and local neural pathways via the neuro-immuno-humoral axis. There may be a decreased systemic inflammatory response after minimally invasive surgery; however, it is unclear whether this is due to a reduced local peritoneal reaction.

CONCLUSIONS

Interventions that dampen the peritoneal response and/or block the neuro-immuno-humoral pathway should be further investigated as possible avenues of enhancing recovery after surgery, and reducing postoperative complications.

Destruction of gastric cancer cells to mesothelial cells by apoptosis in the early peritoneal metastasis

This study examined the mechanism by which the gastric cancer cells lead to early peritoneal metastasis. HMrSV5 cells, a human peritoneal mesothelial cell line, were co-incubated with the supernatants of gastric cancer cells. Morphological changes of HMrSV5 cells were observed. The cell damage was quantitatively determined by MTT assay. The apoptosis of HMrSV5 cells was observed under transmission electron microscope. Acridine orange/ethidium bromide-stained condensed nuclei was detected by fluorescent microscopy and flow cytometry. The expressions of Bcl-2 and Bax was immunochemically evaluated. The results showed that conspicuous morphological changes of apoptosis were observed in HMrSV5 cells 24 h after treatment with the supernatants of gastric cancer cells. The supernatants could induce apoptosis of HMrSV5 cells in a time-dependent manner. The supernatants could up-regulate the expression of Bax and suppress that of Bcl-2 in HMrSV5 cells. These findings demonstrated that gastric cancer cells can induce the apoptosis of HPMCs through supernatants in the early peritoneal metastasis. The abnormal expressions of Bcl-2 and Bax may contribute to the apoptosis. Anti-apoptosis drugs promise to be adjuvant chemotherapeutic agents in the treatment of peritoneal metastasis of gastric cancer.

Neutralization of fibroblast growth factor-2 reduces intraarticular adhesions

Adhesion is a serious complication after trauma or surgery. Because adhesion formation is essentially a fibrogenetic process, a series of growth factors are assumed to be involved in its development. If this is true, it may be possible that inhibition of the growth factor activity suppresses adhesion formation. The current study was conducted to verify this hypothesis on fibroblast growth factor-2 using an intraarticular adhesion model in the rabbit knee. Forty Japanese White rabbits were used. They were divided randomly into five groups of eight animals, and in three of them, activity of endogenous fibroblast growth factor-2 was suppressed locally by a neutralizing antibody. The remaining two groups served as controls, and formation of adhesions was evaluated 4 weeks after surgery. The results showed that the administration of the antibody reduced the extent of adhesions macroscopically, whereas histologic observation and collagen content measurement suggested the adhesion tissue was not affected significantly. Corresponding to the macroscopic findings, contraction of the knee was improved in the antibody groups. The findings showed that suppression of fibroblast growth factor-2 activity reduces adhesions. It is expected that control of the cytokine activity may become a novel method for reducing adhesions.

Effect of a Composite Membrane of Chitosan and Poloxamer Gel on Postoperative Adhesive Interactions

Excessive postoperative adhesion formation is a major result of surgery. The adhesion reduction effects of a chitosan membrane and poloxamer gel barrier were measured in a rat peritoneal model. Forty-four male Sprague-Dawley rats were divided into four groups (control, poloxamer, chitosan, and poloxamer+chitosan sandwich). Two cm2 of cecal serosa and the adjacent abdominal wall were abraded. The denuded cecum was covered with either a chitosan membrane, a poloxamer gel, chitosan in a sandwich configuration with poloxamer on both sides, or neither (control group) and apposed to the abdominal wall. Fourteen days after surgery adhesions were graded using a whole-number scoring system of zero to five. Adhesion strength was determined using a whole-number system of one to four. Adhesion area was measured on a continuous scale of adhesion severity. Adhesion grades were highest in the control group (5.00 ± 0.00) and were significantly ( P < 0.05) lower in the poloxamer group (3.50 ± 1.35), the chitosan group (1.64 ± 1.63), and the poloxamer+chitosan group (1.18 ± 1.25). The two chitosan-containing groups also had significantly ( P < 0.05) reduced adhesion grades in comparison with the poloxamer group. Adhesion area in both chitosan-containing groups was reduced in comparison with control and adhesion strength was reduced significantly ( P < 0.05) in all groups compared with control. The poloxamer+chitosan group had significantly ( P < 0.05) reduced adhesion strength versus poloxamer only. There was a significant ( P < 0.05) linear correlation ( r = 0.931, P < 0.001) between adhesion grade and adhesion strength. We conclude that chitosan and the combination of poloxamer+chitosan were shown to effectively reduce adhesion area, grade, and strength.

Changes of cytokine profiles during peritonitis in patients on continuous ambulatory peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) has emerged as an important dialysis treatment modality worldwide. One of the major complications is bacterial peritonitis, which may result in subsequent technique failure because of loss of peritoneal clearance or peritoneal fibrosis. Bacterial peritonitis leads to the release of proinflammatory cytokines from resident and infiltrating cells in the peritoneal cavity. We studied 35 patients undergoing CAPD with acute bacterial peritonitis. All patients treated with antibiotics for 2 weeks after the clinical diagnosis of peritonitis had a good recovery. Peritoneal dialysate effluent (PDE) was collected on days 1, 3, 5, 10, 21, and 42 after the start of treatment. Cell populations were monitored by flow cytometry. PDE levels of interleukin-1beta (IL-1), IL-6, transforming growth factor-beta (TGF-beta), and basic fibroblast growth factor (FGF) were measured by enzyme-linked immunosorbent assay. Gene transcription of TGF-beta in macrophages from PDE was measured by quantitative polymerase chain reaction. Bacterial peritonitis was associated with a sharp increase in total cell and neutrophil counts (400-fold) in PDE up to 3 weeks after peritonitis despite clinical remission (P < 0.0001). There was an increased absolute number of macrophages during the first 3 weeks despite the reduced percentage of macrophages among total cells in PDE compared with noninfective PDE. There was a progressive increase in the percentage of mesothelial cells or dead cells in the total cell population in PDE over the entire 6-week period. PDE levels of IL-1, IL-6, TGF-beta, and FGF increased markedly on day 1 before their levels decreased gradually. PDE levels of these cytokines or growth factors were significantly greater than those in noninfective PDE (n = 76) throughout the study period (P < 0.01). Similarly, TGF-beta complementary DNA (cDNA) molecules per macrophage were significantly greater than those of macrophages in noninfective PDE throughout this period (P < 0.01). There was no significant correlation between PDE levels of TGF-beta and TGF-beta cDNA molecules per macrophage, suggesting that peritoneal macrophages are not the only source of TGF-beta in PDE. We conclude there is an active release of proinflammatory cytokines and sclerogenic growth factors through at least 6 weeks despite apparent clinical remission of peritonitis. The peritoneal cytokine networks after peritonitis may potentially affect the physiological properties of the peritoneal membrane.

Activated mesothelial cells produce heparin-binding growth factors: implications for tumour metastases

Curative surgery for gastrointestinal malignancy is commonly thwarted by local tumour recurrence. The heparin-binding growth factors, basic fibroblast growth factor (bFGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF) and vascular epidermal growth factor (VEGF) are all implicated in the metastatic process, but whether or not these essential growth factors are produced by the activated peritoneum is unknown. This study reveals that peritoneal mesothelial cells constitutively express mRNA for bFGF, HB-EGF and two VEGF spliced variants, VEGF121 and VEGF165. Mesothelial activation with interleukin (IL)-1b or tumour necrosis factor (TNF)-a produced an up-regulation of mRNA for HB-EGF and VEGF, but not bFGF expression. IL-6 failed to stimulate growth factor expression, whereas IL-2 produced a marked suppression in HB-EGF and bFGF, but not VEGF expression. Mesothelial cells were shown to predominantly express mRNA for the intermediate affinity (bg(c)) IL-2 receptor. Cytokine-induced growth factor up-regulation was confirmed at the protein level using Western blotting of mesothelial cell lysates for HB-EGF and culture supernatant enzyme-linked immunosorbent assay for VEGF. The production of these growth factors by human mesothelial cells may play a significant role in post-operative peritoneal tumour recurrence. Their common heparin-binding property offers a potential therapeutic target for manipulating the growth factor environment of the human peritoneum.

Adhesion preventive effect of hyaluronic acid after intraperitoneal surgery in mice

Prevention of intraperitoneal adhesion after gynaecological surgery is essential for maintaining postoperative fertility. In this study, the adhesion prevention effect was examined of a hyaluronic acid (HA) solution obtained from the fermentation method and having a molecular weight of 1.9x10(6) with high viscosity. Laparotomy was conducted on female mice 7 weeks old, whose menstrual periods were synchronized by pregnant mare serum gonadotrophin (PMSG) to injure the uterine horn surface. Intraperitoneal adhesions were favourably formed in 91.7% of cases induced with iodine abrasion, compared with 50% induced by electrosurgery. Intraperitoneal administration of HA was evaluated for its effect on the prevention of adhesions made by iodine abrasion. Adhesion prevention effects of HA were observed at concentrations of 0.3, 0.5, 0.75 and 1.0%, among which the most pronounced effect was with the use of a 0.3% solution (92.3% of cases). Compared with the control group adhesion score of 2.0 +/- 0. 8, significant decreases in adhesion scores were observed at all concentrations. HA with a molecular weight of 1.9x10(6) was recognized to have a definitive prevention effect on postoperative adhesions in mice after laparotomy and is considered to be a prospective material for future clinical use.

The temporal efficacy of early second-look lysis of adhesions in reducing postoperative adhesions in a murine model

OBJECTIVE

Our aim was to determine whether early second-look lysis of adhesions reduces postoperative adhesions.

STUDY DESIGN

With the murine uterine horn model, early second-look lysis of adhesions was performed 5, 7, 14, and 21 days after an electrocautery injury. Sites with adhesions (between 36 and 46/time point) underwent lysis of adhesions. Fourteen days later, a reviewer blinded to the treatment assessed adhesion formation, including adhesions not present at early second-look lysis of adhesions (eg, de novo adhesions).

RESULTS

The rate of adhesion formation was 49% of control sites, unchanged when the early second-look lysis of adhesions was performed at 5 (44.4%) and 7 (39.5%) days, reduced at 14 days (28.6%), and increased at 21 days (74%). The pattern of de novo adhesions was similar, 17.6% when the early second-look lysis of adhesions was performed at 5 days, 10% at 7 days, 0% at 14 days, and 28.6% at 21 days. The only histologic difference between the groups was neovascularity at day 21.

CONCLUSIONS

Early second-look lysis of adhesions was effective in reducing postoperative adhesions only when performed at 14 days in this model, suggesting that the specific cellular events occurring at the time of the early second-look lysis of adhesions are critical to efficacy.

Pelvic adhesions contain sex steroid receptors and produce angiogenesis growth factors

OBJECTIVE

To evaluate female pelvic adhesion tissue for the presence of estrogen receptor (ER), progesterone receptor (PR), basic fibroblastic growth factor (basic-FGF), and vascular endothelial growth factor (VEGF).

DESIGN

Descriptive study.

SETTING

Patients at a tertiary medical center.

PATIENTS

Female reproductive age patients undergoing gynecologic surgery who were not receiving hormonal therapy.

INTERVENTIONS

Female reproductive tract peritoneal adhesion tissue was excised, frozen, and sent for immunohistologic evaluation.

MAIN OUTCOME MEASURE

Presence of ER, PR, basic-FGF, and VEGF in adhesion tissue.

RESULTS

Nineteen of 19 specimens were positive for PR; 16 of 19 specimens were positive for ER, which was present in a variety of the different cell types constituting adhesion. Vascular endothelial growth factor and basic-FGF were detected in endothelial cells of blood vessels supplying this tissue as well as in mesothelial cells.

CONCLUSION

Adhesion tissue contains ER, PR, and growth factors that may be important in the genesis of the permanent fibrovascular bands between pelvic organs. This supports the theoretical possibility of hormonal manipulation of these tissues to negatively influence postoperative pelvic adhesion formation.

The peritoneal response to expanded polytetrafluoroethylene and oxidized regenerated cellulose surgical adhesion barriers

OBJECTIVE

To determine the peritoneal response to the surgical adhesion barriers expanded-polytetrafluoroethylene (ePTFE) and oxidized regenerated cellulose (ORC).

STUDY DESIGN

The barriers were retrieved from the peritoneal cavities of women and mice 2 hours to 14 days after insertion and subjected to histology and electronmicroscopy.

RESULTS

Macrophages and mesothelial cells rapidly appeared on the surface of both materials. ePTFE was covered by 3 days, with the macrophages gradually being replaced by mesothelium and disappearing thereafter. By 7 days, a delicate membrane with surface mesothelial cells completely enveloped the ePTFE, creating a "pseudoperitoneum". The membrane was difficult to recover as it was fragile and not adherent to the ePTFE. ORC was rapidly infiltrated and degraded by leukocytes and disappeared by 5 days in mice and from all but 1 of 20 women by 11 days.

CONCLUSIONS

ePTFE is rapidly encapsulated by a non-adherent membrane resembling peritoneum while ORC is rapidly infiltrated and degraded by peritoneal fluid leukocytes.

The effect of surgical glove powder on proliferation of human skin fibroblast and monocyte/macrophage

The effect of surgical glove powders (Biosorb, Keoflo, and CaCO3) and Hydrocote (powder-free lubricating agent, Biogel) was examined on human skin fibroblasts and monocyte/macrophage cell lines (U937 and HL-60). Glove powders (0.1-100 micrograms/ml) in the presence of 10% fetal bovine serum (FBS) had no significant effect on the rate of 3H-thymidine uptake and proliferation of these cells after 48 h and 7 days of exposure, respectively. However, they inhibited HL-60 growth after 10 days, and Biosorb and CaCO3 inhibited U937 after 10-21 days of exposure compared with control. In the presence of low serum (0.5%), Biosorb, but not Keoflo, CaCO3, and Hydrocote, inhibited HL-60 cells after the third day of exposure (p < 0.05), whereas they were without any effect on U937 cells. Further incubation resulted in a significant decrease in cell density in all treatments, as well as controls, because of cell death. In the presence of 2% serum, glove powder-treated HL-60 significantly increased in cell numbers during the first 3 days, and the cells became stationary thereafter, whereas Keoflo and CaCO3-stimulated U937 reached a maximal by 9 days of treatment. Coculturing of fibroblasts directly with macrophages (0.4-5 x 10(5) cells per dish) or incubation with macrophage culture-conditioned media (CCM) stimulated quiescent fibroblast growth equal to that induced by 10% and 0.5% serum, respectively (p < 0.05). However, incubation of fibroblasts with glove powder-treated HL-60 CCM (except CaCO3) inhibited (p < 0.05) and CCM from Biosorb-treated U937 stimulated (p < 0.05) fibroblast proliferation. The CCM from glove powder-treated HL-60 and U937 did not have any significant effect on the rate of 3H-thymidine incorporation into fibroblasts compared with controls. The present observations suggest that glove powder action on fibroblast and macrophage growth in vitro depends on both the serum concentration of the culture medium and the length of exposure. The results imply that glove powders may have an adverse effect in vivo by directly influencing the biologic activity of macrophages, as well as other cell types, leading to alterations in the early phases of wound healing.

Identification of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor in surgically induced pelvic adhesions in the rat and intraperitoneal adhesions in the human

OBJECTIVE

Our purpose was to determine the presence and cellular distribution of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor in surgically induced pelvic fibrous adhesions in rat uterine horns subjected to burn, crush, and debridement injury and intraperitoneal fibrous adhesions formed to various organs in the human.

STUDY DESIGN

A total of 15 injured and five uninjured rats were used in this study, and fibrous adhesions and intact peritoneum were removed for processing 2 weeks after surgery. Fibrous adhesions formed to uterine, ovarian, and oviductal tissues and the peritoneal wall from eight patients who had gynecologic surgery were also collected. The tissues were processed for immunohistochemical localization of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor with specific antibodies to human and rat epidermal growth factor and transforming growth factor-alpha and the extracellular binding domain of the epidermal growth factor receptor.

RESULTS

All the cell types in the rat fibrous adhesion immunostained for epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor. The highest immunostaining intensity for epidermal growth factor was associated with inflammatory cells infiltrated into the fibrous adhesion, followed by arteriole endothelial and smooth muscle cells, fascial striated muscle, and fibroblasts of the fibrous adhesion. In the uterine tissue at the site of injuries myometrial smooth muscle cells, in addition to inflammatory cells that migrated among stromal cells, also immunostained for epidermal growth factor. Fibrous adhesions also immunostained for transforming growth factor-alpha with three separate polyclonal antibodies to the amino and carboxy termini of transforming growth factor-alpha precursor and the mature transforming growth factor-alpha, with no substantial differences in their intensity and pattern compared with epidermal growth factor. The pattern and cellular distribution of epidermal growth factor receptor was similar to that seen for epidermal growth factor and transforming growth factor-alpha. Fibrous adhesions from patients with intraperitoneal adhesions immunostained for epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor with a pattern and intensity similar to that observed in fibrous adhesions in the rats.

CONCLUSIONS

The data suggest that epidermal growth factor and transforming growth factor-alpha may play a key role both in normal mechanism of peritoneal repair after injury and formation and maintenance of fibrous adhesions.

Adhesions after extensive gynecologic surgery: clinical significance, etiology, and prevention

Postoperative adhesions occur in 60% to 90% of patients undergoing major gynecologic surgery and represent one of the most common causes of intestinal obstruction in the industrialized world. The incidence of adhesion-related intestinal obstruction after gynecologic surgery for benign conditions without hysterectomy is approximately 0.3%, increasing to 2% to 3% among patients who undergo hysterectomy, and is as high as 5% if a radical hysterectomy is performed. Other adhesion-related complications include chronic pelvic pain, ureteral obstruction, and voiding dysfunction. Intraperitoneal adhesions also can limit the effectiveness of intraperitoneal therapeutic agents used in cancer treatment. Postoperative adhesions are sequelae of impaired fibrinolysis of the fibrin and cellular exudate after peritoneal injury. Adequate blood supply is essential for normal fibrinolysis. Therefore factors that increase ischemia and potentiate adhesion formation include thermal injury, infection, presence of a foreign body, and radiation-induced endarteritis. Only recently, appropriate animal models have been developed to study the process of adhesion formation and prevention. Until clinical confirmation of findings from these investigations exists, only a meticulous surgical technique can be advocated to minimize these untoward effects of surgery.

Adhesions after extensive gynecologic surgery: clinical significance, etiology, and prevention

Postoperative adhesions occur in 60% to 90% of patients undergoing major gynecologic surgery and represent one of the most common causes of intestinal obstruction in the industrialized world. The incidence of adhesion-related intestinal obstruction after gynecologic surgery for benign conditions without hysterectomy is approximately 0.3%, increasing to 2% to 3% among patients who undergo hysterectomy, and is as high as 5% if a radical hysterectomy is performed. Other adhesion-related complications include chronic pelvic pain, ureteral obstruction, and voiding dysfunction. Intraperitoneal adhesions also can limit the effectiveness of intraperitoneal therapeutic agents used in cancer treatment. Postoperative adhesions are sequelae of impaired fibrinolysis of the fibrin and cellular exudate after peritoneal injury. Adequate blood supply is essential for normal fibrinolysis. Therefore factors that increase ischemia and potentiate adhesion formation include thermal injury, infection, presence of a foreign body, and radiation-induced endarteritis. Only recently, appropriate animal models have been developed to study the process of adhesion formation and prevention. Until clinical confirmation of findings from these investigations exists, only a meticulous surgical technique can be advocated to minimize these untoward effects of surgery.

The formation of coalescing peritoneal adhesions requires injury to both contacting peritoneal surfaces

OBJECTIVE

To determine whether surgical trauma to one or both contacting peritoneal surfaces is necessary to cause coalescing adhesions.

SETTING

Research laboratory.

DESIGN

The abdominal wall peritoneum and one or both contacting medial peritoneal surfaces of surgically approximated uterine horns in mice were injured by electrocautery, cutting, scratching, or scraping. Adhesion formation was assessed visually and histologically 3 and 7 days later.

RESULTS

Regardless of the type of peritoneal injury, few adhesions resulted when only a single injury was made to the abdominal wall (< or = 6%) or to one uterine horn (< or = 13%). When both opposing uterine surfaces were injured, however, adhesions formed at 57% of the sites after electrocautery, 100% after cutting, 100% after scratching, but 0% after scraping. When previously created uterine adhesions were lysed, they reformed at 15 of 15 sites with and 12 of 13 (92%) sites without electrocautery for hemostasis at the time of lysis.

CONCLUSIONS

In this murine model, the development of postsurgical adhesions required surgical trauma to both contacting peritoneal sites, regardless of the type of injury, the mobility of the opposing peritoneal surfaces or whether hemostasis was achieved. The clinical implications are that more attention needs to be focused on protecting contacting normal peritoneal surfaces from inadvertent injury during surgery and that different therapeutic strategies may be required for prevention of adhesion formation and reformation because of the high probability of contact between injured peritoneal surfaces with the latter.

Expanded-polytetrafluoroethylene but not oxidized regenerated cellulose prevents adhesion formation and reformation in a mouse uterine horn model of surgical injury

OBJECTIVE

To evaluate the ability of the two currently available surgical barriers, oxidized regenerated cellulose and expanded-polytetrafluoroethylene (PTFE), to prevent postsurgical adhesions.

DESIGN

Murine uterine horns were approximated in the midline and the contacting uterine surfaces injured by electrocautery, cutting, and scratching, with and without barriers interposed. Sham-operated and experimental animals had adhesions assessed visually and histologically 7 days postoperatively. In another group, adhesions were created and then lysed 7 days later with barriers interposed. Readhesion formation was assessed 14 days after lysis with the PTFE being removed 7 days after lysis.

SETTING

Research laboratory

RESULTS

Adhesions occurred at 58.5% of the electrocautery sites without barriers, 100% of the readhesion sites with recautery for hemostasis, and 92% of the recautery sites without hemostasis. None of the sham-operated sites developed adhesions. When oxidized regenerated cellulose was interposed, adhesions were observed at 36% of uninjured uterine horn sites, 62% with single and 92% with double electrocautery injuries and 90% of the reformation sites. The PTFE did not cause adhesions in uninjured controls and completely prevented adhesion formation and reformation, regardless of the type of injury or whether hemostasis was achieved. A thin cellular membrane, continuous with the uterine serosa, enveloped the PTFE.

CONCLUSIONS

Expanded-polytetrafluoroethylene, but not oxidized regenerated cellulose, prevents adhesion formation and reformation in this murine uterine horn model. Additionally, oxidized regenerated cellulose was adhesiogenic even without surgical injury.

Function of peritoneal exudate cells after abdominal surgery

Peritoneal macrophages and polymorphonuclear neutrophils are key cells in the repair of postoperative injury. Increased numbers of macrophages migrate into the peritoneal cavity after operation and the function of these cells changes over the postoperative interval. Macrophage activities, such as respiratory burst, arachidonic acid metabolism, monokine secretion, and plasminogen activator inhibitory activity, are elevated by peritoneal operation. However, the secretion of plasminogen activator activity is decreased after operation. The kinetics with which each of these functions changes varies with the parameter examined, indicating a complex regulation of the differentiation of leukocytes after operation. In addition, the activity of postoperative macrophages can be modulated in vitro by exposure to cytokines and conditioned media from polymorphonuclear neutrophils and macrophages. Thus, cell-cell interactions and factors secreted within the peritoneal cavity may regulate the contribution of postoperative leukocytes to peritoneal repair after operation.

Modulation of peritoneal re-epithelialization by postsurgical macrophages

The studies reviewed here show that postsurgical macrophages are capable of modulating the proliferation of TRC. That is, macrophages either suppress or enhance the proliferation of TRC depending on the culture time and the medium used as a comparison, i.e., culture medium with only serum or spent medium from cultures of resident peritoneal macrophages. Postsurgical macrophages also modulate the morphology of (spindly or rounded appearance) and the secretion of extracellular matrices by TRC. The responsivity of TRC to control by postsurgical macrophage-spent media or growth factors changes as a function of postsurgical and/or culture time. In addition, cells harvested from the site of peritoneal trauma (TRC) did not respond to growth factors in a fashion entirely the same as fibroblasts. This indicates that cells harvested from the site of peritoneal injury are unique. Lastly, after removal of a suppressive factor from postsurgical macrophage-spent media by dialysis, the factors secreted by postsurgical macrophages are more potent in enhancing TRC proliferation than growth factors individually.

Epidermal growth factor accelerates connective tissue wound healing in the perforated rat mesentery

Epidermal growth factor (EGF) has been reported to stimulate healing of wounds in skin, cornea, and gastric mucosa. In the present study, we further investigate the effect of endogenous and exogenous EGF in healing of connective tissue wounds using the rat perforated mesentery model. Healing of mesenteric perforations is accomplished by the connective tissue fibroblasts since there are no interfering variables such as interactions of epithelial cells, desiccation, or foreign materials such as sutures or subcutaneous implants. We performed laparotomy in 114 adult male Sprague-Dawley rats and made 20 standardized perforations in the mesentery of each rat with a scalpel. Rats were randomly assigned to five groups. Group I received no treatment after surgery; Group II received intraperitoneal injections of phosphate-buffered saline (PBS) after surgery and then twice daily for the following 3 days; Group III received 10 micrograms of EGF in the PBS injections according to the same regimen as Group II; Group IV had sham exploration of the submandibular salivary glands; and Group V animals had excision of the submandibular glands 3 days before laparotomy to deprive the main source of EGF in rat. On Days 4 through 10 after surgery rats were sacrificed and the percentage of perforations in each rat which were closed was determined. The curves for the time course of wound closure for Groups IV and V were not different indicating that endogenous submandibular EGF does not play a role in healing of mesenteric wounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of interleukin-1 (IL-1) on postsurgical macrophage secretion of protease and protease inhibitor activities

Although peritoneal macrophages secrete a variety of inflammatory mediators and proteases during postsurgical repair of the peritoneum, regulation of this secretion is poorly understood. Here, the responsivity of peritoneal macrophages to interleukin-1 (IL-1) stimulation in vitro, measured by the secretion of protease and protease inhibitor activities, was evaluated as a function of postsurgical time. Macrophages were harvested at various times after peritoneal sidewall abrasion, isolated by discontinuous density centrifugation and cultured with varying concentrations of IL-1. IL-1 increased the secretion of plasminogen activator (PA) activity by peritoneal macrophages in a concentration-dependent manner on postsurgical Days 0, 3, 10, and 14. Macrophages harvested on postsurgical Day 1 after surgery responded only to high concentration of IL-1, while on Days 5 and 7 all doses of IL-1 stimulate PA. On Days 7, 10, and 14 after surgery, the secretion of PA activity (after acid treatment) by postsurgical macrophages was generally high and increased with IL-1 treatment. The level of PA activity after inactivation of acid labile inhibitors (PAI) also increased in a dose-dependent manner on Days 0, 3, and 5. Although Day 1 macrophages expressed the highest PAI activity of all groups, they had relatively low responsivity to IL-1 with regards to PAI secretion. The level of elastase activity by postsurgical macrophages was lowest on Day 1, highest on Day 7, and decreased thereafter. All concentrations of IL-1 inhibited elastase activity of macrophages on Day 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of transforming growth factor beta on postoperative adhesion formation and intact peritoneum

Transforming growth factor beta (TGF beta) is an extremely potent chemoattractant for macrophages, mononuclear leukocytes, and fibroblasts. It also acts as a potent stimulant for collagen and fibronectin synthesis and inhibits epithelial cell growth. TGF beta plays an important role in healing many types of wounds, but its role in peritoneal adhesion formation is not known. These studies were performed to determine if TGF beta could affect postoperative wound healing in a rat model. In the first experiment, 20 rats were divided into two groups and received either 2 micrograms TGF beta or control diluent IP daily for 5 days after surgical injury to the uterine horns. The severity of the adhesions were graded 2 weeks postoperatively using a score of 0-3. The TGF beta group showed a higher adhesion score at 2 weeks compared to control, 2.9 +/- 0.34 and 1.6 +/- 0.61, respectively (P less than 0.001). On H&E stained sections of the adhesions, there was an increase in the number of both inflammatory cells and fibroblasts in the TGF beta-treated animals. A comparison trial of bone-derived TGF beta (a gift from Collagen Corporation, Palo Alto, CA) versus recombinant TGF beta (a gift from Oncogen, Seattle, WA) versus control using the same protocol as above showed that both sources of TGF beta were more effective in promoting postoperative adhesions when compared to controls, and there was no difference between TGF beta groups, 3.0 +/- 0 for both TGF beta groups, and 2.2 +/- 0.91 for control (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Time course of wound healing

Wound healing is a special kind of inflammation. Undisturbed wound healing is subject to a fixed time schedule of biochemical and cellular events. It is virtually impossible to deal with the time course of wound healing without describing the cellular and non-cellular events involved. The activity and mode of cell action after injury are coordinated by spatial and chronological factors, as well as by different mediators and cell-cell interacting signals. During wound healing the sequence of different signals and message substances, such as mediators of inflammation, fulfill a key function in wound repair. The report describes the time course of healing and the control of cellular events by different mediators and cell interactions. Emphasis is placed on temporal aspects, including the various signals leading to typical cellular events in wound healing.

Regulation of proliferation of peritoneal tissue repair cells by peritoneal macrophages

Macrophages produce soluble mediators which modulate fibroblast growth during tissue repair. Interaction between tissue repair fibroblasts (TRC) and regulatory proteins from surgically elicited macrophages is important for peritoneal reepithelialization. In this study, we compared the effects of an extract from postsurgical macrophage spent medium with those of known growth factors on TRC collected from injured peritoneum to evaluate certain characteristics of macrophage secretory products on peritoneal healing. Rabbits underwent a midline laparotomy followed by resection and reanastomosis of the ileum or abrasion of the abdominal wall. TRC were then collected at various times after surgery. Peritoneal macrophages recovered from nonsurgical or postsurgical rabbits were cultured for 2 days in vitro. The peak of thymidine incorporation by TRC occurred on day 5 after surgery; this gradually decreased with extended postsurgical times. Fibroblast growth factor and epidermal growth factor stimulated, whereas TGF-beta inhibited, [3H]thymidine incorporation into TRC. Maximal thymidine incorporation occurred when TRC from Postsurgical Day 5 were cultured with an extract from postsurgical macrophage spent medium. However, when TRC recovered from Postsurgical Days 2 and 10 were cultured with an extract of postsurgical macrophage spent medium, they showed greater stimulation than Day 5 TRC. These data suggest that postsurgical macrophages may produce an array of factors that stimulate fibroblast growth and differentiation and may in turn affect tissue repair throughout the wound healing process.