Morphology of the rat peritoneum after carbon dioxide and helium pneumoperitoneum: a scanning electron microscopic study

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

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

Does thermodynamic stability of peritoneal collagen change during laparoscopic cholecystectomies? A differential scanning calorimetry (DSC) study

Background

Carbon dioxide pneumoperitoneum used during laparoscopic surgeries alters the integrity of the peritoneum and results in denudation of the basal lamina that might cause altered immune response, inhibited fibrinolysis, hypoxia, and acidosis. The changes in the structure of pneumoperitoneum were described as bulging of mesothelial cells, irregular cell junction’s cell membrane degradation, and mesodermal edema. As denaturation of peritoneal proteins reflects overall condition of its structure and interactions with the surrounding molecules, the physical status of collagen was assessed on the basis of parameters of thermal denaturation measured by DSC method.

Methods

Twenty-four female patients operated on due to cholelithiasis were enrolled in this study. Laparoscopic cholecystectomy was performed using standard four-trocar technique, and standard values of insufflated carbon dioxide pneumoperitoneum were used. After trocar placement, the first collection of peritoneal sample (sample A) was performed. The second peritoneal sample (sample B) was collected after the removal of gall bladder. Differential scanning calorimetry (Q200 calorimeter, TA Instruments) was performed on samples defrosted at room temperature.

Results

In all samples of peritoneum, a nonreversible endothermal process recognized as denaturation was observed. Sample B obtained at the end of surgery did not differ from sample A obtained at the beginning in terms of all parameters under study. Temperature of denaturation in A and B was correlated only marginally, but enthalpy and specific heat were significantly correlated. The analysis of data from DSC measurements did not reveal differences in physical stability of collagen in peritoneal samples obtained at the beginning and at the end of surgery. Significant negative correlations between duration of CO₂ pneumoperitoneum and enthalpy of denaturation in sample B were found.

Conclusions

Differences in enthalpy of denaturation may reflect a quantitative relation between amount of native collagen molecules in the sample and other, non-collagenous components or impaired collagen.

Structural deteriorations of the human peritoneum during laparoscopic cholecystectomy. A transmission electron microscopic study

BACKGROUND

In previous studies, changes in the surface of the peritoneum during laparoscopic surgery are well defined. Nevertheless, almost all of these studies were performed on rodents via scanning electron microscopy. In the present study, structural alterations of the mesothelial cells of peritoneum were examined during laparoscopic cholecystectomy using transmission electron microscopy.

METHODS

Twenty patients with symptomatic cholelithiasis were included in the study. Peritoneal biopsy was performed immediately after CO2 pneumoperitoneum creation and at the end of surgery just before gallbladder removal. Biopsies were taken from the right upper quadrant, i.e., apart from operative manipulation. Peritoneal sample cross-sections were compared using transmission electron microscopy.

RESULTS

The carbon dioxide pneumoperitoneum during laparoscopic cholecystectomy caused deteriorations of the peritoneal mesothelium. Apoptosis were developed in mesothelial cells. Bulging of mesothelial cells, irregular cell junctions, focal intercellular clefts, apical cell membrane degeneration, deep nuclear invaginations, and lipid droplets in the cytoplasm of the mesothelial cells were other remarkable findings. Mesothelial edema also was determined.

DISCUSSION

As seen in previous studies, basement membrane nudity appeared after carbon dioxide pneumoperitoneum could be attributable to mesothelial cell apoptosis, deterioration of the cell structure, and cell organelles.

Carbon dioxide-induced inhibition of mechanical activity in gastrointestinal smooth muscle preparations isolated from the guinea-pig

Mechanical responses of smooth muscle elicited by application of CO2-gas bubbled physiological salt solution (CO2-gas solution) were investigated in isolated stomach antrum and colon preparations of the guinea-pig. Circular smooth muscle preparations of both colon and stomach were spontaneously active with periodic generation of phasic contractions. In colonic preparations, the CO2-gas solution produced a biphasic response, with an initial small transient contraction followed by a sustained inhibition of phasic contractions. Removal of the CO2-gas solution allowed a slow recovery of the spontaneous contractions over a period of about 40 min. The recovery developed with a similar time course irrespective of the length of time exposed to CO2-gas solution. The inhibitory responses elicited by CO2-gas solution were not modulated by atropine, Nω-nitro-L-arginine or neostigmine. Atropine-sensitive excitatory responses of smooth muscle elicited by transmural nerve stimulation or exogenously applied acetylcholine were attenuated or abolished in the presence of CO2-gas solution. In stomach preparations, the CO2-gas solution elicited a tri-phasic response, with an initial transient relaxation followed by a transient contraction and then a sustained inhibition of the rhythmic contractions. The peak amplitude of the transient contraction was about 2.5 times larger than the spontaneous phasic contractions. The pH of the CO2-gas solution was reduced to about 6. Application of pH 6 solution again produced a tri-phasic response, as was the case for the CO2-gas solution, however the amplitude of the transient contraction was only about 0.4 times that of the spontaneous contractions. The re-appearance of the abolished phasic contraction was quicker with the pH 6 solution (about 1.8 min) than it was for the CO2-gas solution (about 6 min). The inhibitory responses elicited by the CO2-gas solution could be simulated only partly by the acidified solution, and a possible involvement of additional factors in the inhibition elicited by CO2-gas solution was considered.

Application of stereology to study the effects of pneumoperitoneum on peritoneum

BACKGROUND

Scanning electron microscopy is unable to provide sufficient data to obtain definitive results for research into the morphologic effect of pneumoperitoneum on peritoneum. To overcome this difficulty, we adopted stereology to examine the effect of the type of gas insufflated, pressure, duration, and gas flow on morphologic alterations of peritoneum.

METHODS

Fifty SD rats were divided into ten groups. One group served as control. Pneumoperitoneum was established at 5 mmHg and 1.0 l/min gas flow for 1, 2 or 3 h with CO2 (in groups C1h, C2h, and C3h, respectively) or with He (in groups H1h, H2h, and H3h, respectively). CO2 pneumoperitoneum was further established at 8 mmHg and 1.0 l/min gas flow for 1 h (group C8p), at 5 mmHg and 2.0 l/min gas flow for 1 h (group C2f), and at 5 mmHg and 3.0 l/min gas flow for 1 h (group C3f). After the procedures, five specimens were sampled from anterior peritoneum and measured by stereological and electron-microscopic techniques.

RESULTS

Groups H1h and C1h, H2h and C2h, and H3h and C3h, respectively, were the same in terms of area fraction of basal lamina exposed and diameter of mesothelial cells (P>0.05). The magnitudes of peritoneal trauma in groups C2h, C3h, C8p, C2f, and C3f were significantly higher than that in group C1h (P<0.01), and the same result was observed in groups H2h and H3h against group H1h (P<0.01), and in group C3f against group C2f (P<0.01). Furthermore, the area fractions of basal lamina exposed in groups C3h and H3h were remarkably higher than those in groups C2h and H2h, respectively (P<0.01). The mechanism of basal lamina exposure comprises mesothelial cell desquamation and plasmatorrhexis.

CONCLUSIONS

Peritoneal morphologic trauma during pneumoperitoneum can be attributed to the pressure, duration, and gas flow instead of the type of gas insufflated.

Carbon dioxide modifies the morphology and function of mesothelial cells and facilitates transepithelial neuroblastoma cell migration

BACKGROUND

The response of mesothelial cells to surgical trauma and bacterial contamination is poorly defined. We have recently shown that CO(2) pneumoperitoneum increases systemic metastasis of neuroblastoma cells in a murine model. Thus, we hypothesized that CO(2) alters the morphology and function of mesothelial cells and facilitates transmesothelial tumor cell migration.

MATERIALS AND METHODS

Murine mesothelial cells were exposed to 100% CO(2) and 5% CO(2) as control. Scanning electron microscopy (SEM) investigations, as well as LPS-induced granulocyte-colony stimulating factor (G-CSF) production and mitochondrial activity (MTT assay) were measured. Transmesothelial migration of neuroblastoma cells (Neuro2a) was determined using a transwell chamber system.

RESULTS

CO(2) incubation was associated with a significant destruction of the microvillar formation in SEM. Migration studies showed that the barrier function of the mesothelial monolayer decreased. A significantly increased migration of neuroblastoma cells was identified after 100% CO(2) exposure (P < 0.05). Although the conversion of MTT as an indicator of mitochondrial activity was only slightly and not significantly reduced after CO(2) incubation, the release of G-CSF induced by LPS was completely blocked during the incubation with 100% CO(2) (P < 0.05). The capacity of G-CSF release recovered after the incubation.

CONCLUSION

We observed that peritoneal mesothelial cells lose their typical cell morphology by CO(2) incubation, which is accompanied by facilitated migration of neuroblastoma cells. Moreover, the synthesis of immunological factors is blocked, but this effect is not long lasting. These mechanisms may explain an increased metastasis rate of neuroblastoma cells after CO(2) pneumoperitoneum, which was recently observed in a murine model.

Anti-beta1 integrin antibody reduces surgery-induced adhesion of colon carcinoma cells to traumatized peritoneal surfaces

OBJECTIVE

To study the mechanisms behind surgery-induced augmentation of tumor outgrowth.

SUMMARY BACKGROUND DATA

Surgery provides the best chance of cure for most primary intra-abdominal carcinomas. Effective treatment is however relatively frequent complicated by peritoneal recurrences, which often originate from free-floating intraperitoneal tumor cells that implant on peritoneal surfaces. We previously reported that surgical trauma promotes development of peritoneal metastases.

METHODS

Evaluation of adhesion of CC531s rat colon carcinoma cell line intraperitoneally after laparotomy using in vivo, ex vivo, and in vitro models. Also, human ex vivo models were used to study peritoneal tumor cell adhesion.

RESULTS

Peritoneal imprints of operated rats showed that direct damaging of the peritoneum resulted in enhanced adhesion of rat CC531 colon carcinoma cells to submesothelial extracellular matrix (ECM) proteins in vivo, which was confirmed by electron microscopy. Additionally, the inflammatory reaction of the peritoneal cavity led to retraction of mesothelial cells, hereby also exposing ECM at peritoneal surfaces that had not been traumatized directly. Furthermore, we demonstrated that beta1 integrin subunits represented the primary mediators involved in adherence to either isolated ECM components or excised traumatized rat and human peritoneum. Importantly, incubation of CC531s cells with anti-beta1 integrin antibodies resulted in a significant decrease of tumor cell adhesion in vivo.

CONCLUSIONS

Surgical trauma results in exposure of ECM at directly and nondirectly damaged peritoneal surfaces, leading to increased beta1 integrin-dependent tumor cell adhesion. Perioperative therapies, which aim to block beta1 integrin subunits, might therefore serve as new clinical tools for the prevention of peritoneal recurrences.

Cœlioscopie et cancer en gynécologie : le point en 2005

All the surgical procedures, which may be required to treat a gynecologic cancer, can be performed endoscopically. However prospective randomized studies required to confirm the oncologic efficacy of the technique are still lacking in gynecology, whereas such studies are available in digestive surgery. Animal studies suggested that the risk of tumor dissemination in non traumatized peritoneum is higher after a pneumoperitoneum than after a laparotomy. Experimental studies also emphasized two points: the surgeon and the surgical technique are essential, all the parameters of the pneumoperitoneum may influence the postoperative dissemination. Changing these parameters we may, in the future, be able to create a peritoneal environment adapted to oncologic patients in order to prevent or to decrease the risks of peritoneal dissemination and/or of postoperative tumor growth. Until the results of prospective randomized studies become available, the preoperative selection of the patients and the surgical technique should be very strict. In patients with endometrial cancer, the laparoscopic approach should be reserved to clinical stage I disease, if the vaginal extraction is anticipated to be easy accounting for the volume of the uterus and the local conditions. In cervical cancer, the laparoscopic approach should be reserved to patients with favorable prognostic factors: stage IB of less than 2 cm in diameter. Laparoscopy is the gold standard for the surgical diagnosis of adnexal masses. But the puncture should be avoided whenever possible. The surgical treatment of invasive ovarian cancer should be performed by laparotomy whatever the stage. In contrast restaging of an early ovarian cancer initially managed as a benign mass, is a good indication of the laparoscopic approach. The laparoscopic management of low malignant potential tumors should include a complete staging of the peritoneum. Knowledge of the principles of endoscopy and of oncologic surgery is required. Teaching and diffusion of endoscopic oncological techniques are among the major challenges of gynecologic surgery within the next few years.