Closed continuous hyperthermic peritoneal perfusion model in mice with peritoneal dissemination of colon 26.

An original model of closed continuous hyperthermic peritoneal perfusion (CHPP) in mice is presented and was found to support the efficacy of intraperitoneal hyperthermia. Closed CHPP was performed after intraperitoneal inoculation of transplantable colon 26 cells into a mouse. Colon 26 cells (5 x 10(4)) were injected into 18 mice. The mice were then allocated to six groups of three each and subjected to peritoneal perfusion over time. Peritoneal washings from each mouse were sampled and counted by the cytosmear method. On day 10 after inoculation, colonies of the disseminated tumour were seen on the mesentery by staining with 0.1% methylene blue for 5 min. The number of tumour nodules on the mesentery was counted. The number of washed-out tumour cells decreased the most at 24 h after inoculation, and 76% of the inoculated cells did not wash out during the peritoneal perfusion procedure. CHPP was performed after 24 h when colon 26 cells were injected into the peritoneal cavity because this status may represent micrometastasis. The total number of nodules on the mesentery in the CHPP group was significantly smaller than that in the control (p < 0.02). In conclusion, because this treatment model is similar to the clinical CHPP, the biostaining model might be useful for the evaluation of peritoneal dissemination and it was unique and valuable in demonstrating an effective treatment for the prevention of peritoneal dissemination.