Influence of different pneumoperitoneal pressures on tumor cell distribution in rats

More Reasonable Animal Model for Study the Effect of Pneumoperitoneum on Abdominal Tumor Cells

Background:

Many animal experimental studies showed that abdominal tumor cells will be widely spread during laparoscopic treatment and grow into metastases. These results are different from clinical observations. There is a hypothesis that too much tumor cells was injected in the animals lead to the results of theses bias. We aim to learn the difference of abdominal cavity volume between human body and the nude mice and to determine reasonable amount of tumor cells in the animal experiments.

Methods:

The insufflated CO₂ volume which represents the capacity of the abdominal cavity was recorded during laparoscopic process in 212 patients and 20 nude mice respectively, the relative volume of nude mice and human body was calculated. Based on data from the literature and this study , the amount of tumor cells in the animal experiments was determined. According to these data, we set up a new animal model and a traditional one respectively, and compared the rate of successful modeling and tumor formation between two animal models.

Results:

The intraperitoneal volumes of humans and nude mice were 3.01±0.36 L and 0.011±0.001 L respectively.The number of tumor cells that be uesd in animal should be approximately 0.26×10⁵ in terms of known data in human beings. Compared with the traditional animal model which formed a large number of intraperitoneal tumor metastasis, the new animal model was shows more moderately, and the rate of successful modeling was similar.

Conclusion:

In animal experiments, to simulate the clinical situation, about 0.26×10⁵ tumor cells should be inject in peritoneal cavity of the nude mice.

Effect of carbon dioxide pneumoperitoneum on human renal cell carcinoma proliferation and metastasis in an orthotropic xenograft nude mouse model

INTRODUCTION

This study aimed to explore the effect of carbon dioxide (CO2) pneumoperitoneum on tumor proliferation and metastasis in an orthotropic xenograft nude mice model of human renal cell carcinoma (RCC) and evaluate the safety of CO2 pneumoperitoneum laparoscopy for treating RCC.

MATERIAL AND METHODS

RCC 786-0 cells were injected to establish an orthotropic xenograft model. Fifty nude mice were given orthotropic inoculations and randomized to five groups: group A (control); group B (CO2 pneumoperitoneum for 2 h); group C (CO2 pneumoperitoneum for 4 h); group D (CO2 pneumoperitoneum for 4 h and 24 h after waking); group E (CO2 pneumoperitoneum for 4 h and 48 h after waking). The proliferation status was observed in RCC specimens by immunohistochemical staining for Ki67. The protein levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were examined by western blotting.

RESULTS

All groups showed similar Ki67-positive staining in RCC samples (p > 0.05). The relative expression of HIF-1α and VEGF gradually increased in both group B and group C, as compared with group A, but only the difference between group C and group A reached statistical significance (p < 0.05). The protein levels of HIF-1α and VEGF decreased in both group D and group E, as compared with group B and group C; however, the differences between group D, group E, and group A did not reach statistical significance (p > 0.05).

CONCLUSIONS

In an orthotropic xenograft nude mice model of RCC, CO2 pneumoperitoneum has no effect on expression of the cellular proliferation marker Ki67. However, CO2 pneumoperitoneum rapidly induces transient expression of HIF-1α and VEGF. Thus, CO2 pneumoperitoneum laparoscopy may be a safe method for treating RCC.