A novel approach to the generation and identification of experimental hepatic metastases in a murine model.

A reproducible model for the selective generation of liver metastases has been developed. The spleen is exteriorized by means of a small subcostal incision and is directly injected with a 1-ml suspension of tumor cells. Tumor cells flow out of the splenic vein into the portal vein and lodge in the liver. Splenectomy is performed approximately 1 minute after tumor cell injection. The procedure is simple, requires a single operative procedure, and is applicable to a wide variety of tumors. Over a 6-month period, more than 3,000 such procedures with the use of 5 different tumors were performed in C57BL/6 mice, resulting in a 1.9% mortality. For reliable enumeration of the number of hepatic metastatic deposits, a suspension of india ink was injected iv, and the liver was removed and bleached with Fekete's solution. Tumor nodules appeared as discrete white nodules against the black background of normal liver parenchyma. This model provides a useful tool for the study of the experimental therapy of hepatic metastases in mice.