Hyaluronic acid secretion during carbon dioxide pneumoperitoneum and its association with port-site metastasis in a murine model

Animal models of colorectal peritoneal metastasis

Colorectal cancer remains an important cause of mortality worldwide. The presence of peritoneal carcinomatosis (PC) causes significant symptoms and is notoriously difficult to treat. Therefore, informative preclinical research into the mechanisms and possible novel treatment options of colorectal PC is essential in order to improve the prognostic outlook in these patients. Several syngeneic and xenograft animal models of colorectal PC were established, studying a wide range of experimental procedures and substances. Regrettably, more sophisticated models such as those giving rise to spontaneous PC or involving genetically engineered mice are lacking. Here, we provide an overview of all reported colorectal PC animal models and briefly discuss their use, strengths, and limitations.

The addition of 4% oxygen to the CO(2) pneumoperitoneum does not decrease dramatically port site metastases

STUDY OBJECTIVE

Port site metastases (PSM) after laparoscopic surgery for advanced-stage ovarian carcinoma are a cause of concern, but the pathophysiology is unknown. Because CO(2) pneumoperitoneum was recently demonstrated to be a cofactor in adhesion formation and tumor implantation in a laparoscopic mouse model, and because both could be prevented by the addition of 4% oxygen to the CO(2) pneumoperitoneum, we wanted to test the hypothesis that PSM could be related to tumor cell hypoxia during CO(2) pneumoperitoneum.

DESIGN

A randomized controlled pilot trial to compare the incidence of PSM in women undergoing laparoscopy with a pure CO(2) pneumoperitoneum in comparison with women with CO(2) pneumoperitoneum with the addition of 4% oxygen (Canadian Task Force classification C).

SETTING

University Hospital Gasthuisberg, Leuven, Belgium.

PATIENTS

Since January 1, 2007, 22 consecutive women undergoing laparoscopy for suspected ovarian cancer with subsequent debulking laparotomy were included.

INTERVENTIONS

Diagnostic laparoscopy with 100% CO(2) versus laparoscopy with addition of 4% oxygen.

MEASUREMENTS AND MAIN RESULTS

In the control group, 9 (47%) PSM found in 19 port sites were excised. In the CO(2)+oxygen group, a similar incidence was found, that is, 8 (50%) PSM in 16 port sites. The incidence of PSM was higher in small women (p <.018) and in high-grade malignancies. The pathophysiology of PSM is unknown, but besides direct wound contamination, aerosolization of tumor cells and gas leaks have been suggested together with a causal relationship with the CO(2) pneumoperitoneum. Tumor cell hypoxia probably is not an important mechanism because PSM were not prevented by adding small amounts of oxygen to the CO(2) pneumoperitoneum.

CONCLUSION

The hypothesis of tumor cell hypoxia by the CO(2) pneumoperitoneum as a mechanism for PSM could not be confirmed.

The effects of CO2 pneumoperitoneum on the apoptotic index in the peritoneum

During laparoscopic surgery, gases such as carbon dioxide (CO(2)), helium, or normal air are insufflated into the intra-abdominal cavity so the surgeon can obtain a clear surgical field; however, this insufflation technique may cause injury to the intra-abdominal organs. This study was undertaken to evaluate the effects of different pressures of CO(2) on the apoptotic index in the peritoneum during laparoscopic surgery. A total of 30 Sprague-Dawley male rats were used in the study. CO(2) was insufflated into the intra-abdominal cavity via an angiocatheter cannula by an insufflator at pressures of 10 and 20 mm Hg over 60 min. In the control group, the cannula was inserted into the intra-abdominal cavity, but no gas was insufflated. After 60 min, the rats were killed; peritoneum was harvested from the abdominal wall and was cultured in the cell culture laboratory. Apoptotic and living cells were detected immunohistochemically, and the apoptotic index was calculated and statistically analyzed. The data collected revealed that the apoptotic index increases in proportion to the level of CO(2) pressure. CO(2) pneumoperitoneum is a very useful technique. Gas pressure must be carefully set during the operation, however, or injured mesothelial cells may cause serious malfunction.

ICAM-1 mediated peritoneal carcinomatosis, a target for therapeutic intervention

Development of peritoneal metastasis is a significant issue in the treatment of abdominal cancers. Primary interaction between tumour cells and the mesothelium is a vital step in initiating this process. Our aim was to determine the role of the intercellular adhesion molecule-1 (ICAM-1) in mesothelial-tumour adhesion and the effectiveness of therapeutic intervention. Mesothelial cells were derived from omental tissue. ICAM-1 expression in resting state, in the presence of TNF-alpha or after the application of heparin or hyaluronan was determined by flow cytometry. Functional effects on tumour adhesion to a mesothelial monolayer were determined via a Calcein-AM in vitro adhesion assay. In vivo studies were performed utilising 30 WAG/rij rats, which underwent mini-laparotomy with the injection of 1 x 10(5 )CC 513 tumour cells intraperitoneally. Tumour growth was assessed macroscopically and microscopically by two independent examiners. Mesothelial cells expressed high level of ICAM-1, which was up-regulated by the presence of TNF-alpha. The introduction of heparin caused a decrease in ICAM-1 expression, however hyaluronan did not affect the expression. A significant decrease in tumour-mesothelial cell adhesion in vitro and complete aberration of tumour growth in vivo was observed with heparin application. In vitro studies showed utilisation of high molecular weight hyaluronan, which was more limited in vivo. These data imply that heparin may be used as a potential therapeutic through a defined molecular mechanism both in vitro and in vivo. Hyaluronan appears to function as a barrier and hence may be unreliable in blocking peritoneal recurrence.

Laparoscopic enhancement of tumour cell binding to the peritoneum is inhibited by anti-intercellular adhesion molecule-1 monoclonal antibody

BACKGROUND

There still remain some concerns over the phenomenon of port-site metastases (PSM) after laparoscopic surgery. The aim of this study was to investigate the effect of the pneumoperitoneum on tumor-mesothelial cell interactions.

METHODS

The adhesion of a colon carcinoma cell line to a mesothelial cell monolayer exposed to carbon dioxide, helium, or air was assessed using an in vitro adhesion assay. Changes in adherence were correlated with alterations in cell surface molecule expression by the mesothelial cells using flow cytometry after exposure to the different environments.

RESULTS

Exposure of the mesothelial cells to an in vitro pneumoperitoneum significantly enhanced tumor cell binding to the mesothelial cell monolayer. No differences in cell viability were observed between the groups. This was associated with increased expression of mesothelial intercellular adhesion molecule-1 (ICAM-1) mediated by nuclear factor kappa-B. The enhanced adhesion was abolished by ICAM-1 inhibition.

CONCLUSIONS

This study demonstrated that the laparoscopic environment increases the susceptibility of the mesothelium to tumor cell adherence, and this may be explained by changes in ICAM-1 expression.

Laparoscopic port-site metastases: etiology and prevention

OBJECTIVE

The purpose of this article is to summarize current hypotheses for the possible sources of laparoscopic port-site metastasis, to review the results of experimental models that support such hypotheses, and to discuss the potential options for preventing these metastases.

METHODS

We performed a Medline search to identify in vitro and in vivo studies and clinical trials that analyzed port-site metastases associated with laparoscopic surgery. We report the incidence of port-site metastases and causative factors associated with this condition.

RESULTS

The estimated incidence of port-site metastases in all patients undergoing laparoscopic surgery for malignant disease is approximately 1-2%. Multiple factors are associated with this complication. Among the most common proposed etiologies are the wound implantations caused by the surgical technique and instrumentation; the leakage of insufflation gas through the ports, known as the "chimney effect"; and the impact of pneumoperitoneum on local immune reactions. Several preventive measures, have been suggested, including careful patient selection, lavage of the peritoneal cavity as well as of the port wounds with cytotoxic agents, and modifications of surgical technique.

CONCLUSIONS

Only through the results of well-conducted large multi-institutional prospective randomized trials will we learn not only the true incidence of port-site metastases, but also the potential factors that lead to the occurrence of this complication.

Abdominal wall recurrences after colorectal resection for cancer: results of the Italian registry of laparoscopic colorectal surgery

PURPOSE

The purpose of the present study was to evaluate prospectively the abdominal wall recurrence rate after laparoscopic resection for colorectal cancer, to analyze the impact of the learning curve on abdominal wall recurrence, and to assess the outcome of those patients.

METHODS

The Italian Registry of Laparoscopic Colorectal Surgery database was analyzed to obtain data on cancer patients with abdominal wall recurrence, concomitant local or distant metastases, and interval between initial surgery and diagnosis of trocar site or minilaparotomy recurrences. The records of the initial procedures and the technique of specimen removal were reviewed.

RESULTS

From January 1992 to July 2000, 2,583 patients (1,753 cases of carcinomas and 830 cases of benign diseases) were recorded. The malignant lesions were located on the right colon in 19 percent, the left colon in 48.8 percent, and rectum in 32.2 percent. Sixteen patients with histologic evidence of colorectal adenocarcinoma recurrences at the abdominal wall were observed (0.9 percent). Ten patients presented an advanced stage (III for 7 patients and IV for 3 patients). Eleven cases occurred during the learning curve period (the first 50 consecutive cases). The median survival time after abdominal wall recurrence diagnosis was 16 (range, 12-60) months. By July 2000 only two patients were alive.

CONCLUSIONS

The results of the Italian prospective Registry of Laparoscopic Colorectal Surgery confirm that the incidence of abdominal wall recurrences is similar to that reported in open studies (<1 percent). Most abdominal wall recurrences occurred in the learning curve period, suggesting that surgical experience may play a role in the development of this outcome. The prognosis of these patients is very poor.

Port site metastasis after diagnostic laparoscopy for upper gastrointestinal tract malignancies: an uncommon entity

BACKGROUND

The role of laparoscopy for diagnosing, staging, and treating intra-abdominal malignancies is increasing. This study was designed to examine the incidence of port site metastasis and open incision site metastasis for upper gastrointestinal tract (GI) malignancies.

METHODS

From a prospective database maintained by the Department of Surgery, patients undergoing laparoscopy for upper GI malignancies were identified. Clinical outcomes and recurrences were noted.

RESULTS

Between January 1993 and January 2001, 1965 laparoscopic procedures were identified. After those patients lost to follow-up were excluded, 1650 procedures were performed in 1548 patients. Port site implantation for all laparoscopies occurred in 13 (.79%) of 1650, with a median time to recurrence of 8.2 months. After laparotomy, open incision site recurrence occurred in 9 (.86%) of 1040 (not significant). Among the patients resected, there were 5 (.60%) of 830 port site recurrences and 7 (.84%) of 830 open incision site recurrences. At the time of diagnosis of recurrence, all of the patients with port site and five of seven with open site implantation had distant or local disease, or both, as well.

CONCLUSIONS

Port site implantation after diagnostic laparoscopy for upper GI malignancy is uncommon, does not seem to be different from open incision site recurrence, and occurs in the setting of advanced disease. Therefore, the risk of port site recurrence cannot be used as an argument against laparoscopy in upper GI malignancy.

Increased expression of P-cadherin mRNA in the mouse peritoneum after carbon dioxide insufflation

BACKGROUND

Although systemic responses to carbon dioxide (CO(2)) pneumoperitoneum have been studied, there have been few reports of local responses within the peritoneum. We investigated the expression of mRNA for adhesion molecules involved in cell-cell interactions, including ICAM-1, VCAM-1, CD44, E-cadherin, P-cadherin, and N-cadherin, after the induction of a CO(2) pneumoperitoneum in mice.

METHODS

Mice were treated with CO(2) pneumoperitoneum (4-6 mmHg for 30 min) and then killed after 24 h, 48 h, and 72 h. The peritoneum of the abdominal wall was resected, and total RNA was extracted by the acid guanidinium thiocyanate-phenol-chloroform extraction procedure, cDNA were synthesized by reverse transcription. Expression of the mRNA for each gene was normalized to that of b-actin for semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The expression of P-cadherin mRNA was significantly increased at 48 h (p = 0.007) and returned to the control level by 72 h after CO(2) pneumoperitoneum. The expression of CD44 increased gradually, reaching a peak at 48 h and returning to the control value by 72 h after CO(2) pneumoperitoneum. Expression of ICAM-1 mRNA was not changed significantly after the application of CO(2).

CONCLUSION

The expression of P-cadherin mRNA in the peritoneum can be induced to repair injuries to mesothelial cells caused by CO(2) pneumoperitoneum.

Enhancement of port site metastasis by hyaluronic acid under CO2 pneumoperitoneum in a murine model

BACKGROUND

The mechanism underlying the development and progression of port site metastasis after laparoscopic surgery for cancer is still not understood. Hyaluronic acid secreted from mesothelial cells is thought to be a key factor that causes adhesion between cancer cells and mesothelial cells. Using a murine model of carbon dioxide (CO2) pneumoperitoneum, we evaluated the effect of exogenous hyaluronic acid on port site metastasis.

METHODS

BALB/c mice were injected with 5 A- 106 human gastric carcinoma (MKN45) cells and divided into four groups treated with or without hyaluronic acid and with or without pneumoperitoneum. Three weeks later, the frequency and weight of port site metastases were determined. The effects of hyaluronic acid on tumorigenicity and tumor growth were examined in mice subcutaneously injected with MKN45 cells.

RESULTS

Port site metastasis occurred significantly less frequently in the pneumoperitoneum-only group than in the pneumoperitoneum-with-hyaluronic-acid group (75% vs 100%, p < 0.05). The port site metastatic tumor weighed significantly less in the control group (anesthesia only) than in the hyaluronic acid group (89 +/- 17 vs 288 +/- 35 mg, p < 0.05); it also weighed less in the pneumoperitoneum-only group than in the pneumoperitoneum-with-hyaluronic-acid group(87 +/- 24 vs 298 +/- 51 mg, p < 0.05). The frequency and weight of tumors in the subcutaneous tissue were not significantly different between groups with or without hyaluronic acid injection (95% vs 90%, 331 +/- 128 vs 322 +/- 115 mg).

CONCLUSIONS

Under CO2 pneumoperitoneum, exogenous hyaluronic acid increased the frequency and weight of port site metastasis in a murine model. Hyaluronic acid secreted from mesothelial cells may be associated with the formation of port site metastasis after laparoscopic surgery for cancer under pneumoperitoneum.