Establishment of lymphangioma model and a study on the promoting effect of murine melanoma cell B16-F1 on the lymphangiogenesis in vitro.

To establish an animal model of benign lymphangiomas of C57BL/6 mouse in vitro and to observe the effect of mouse ascites melanoma cell B16-F1 on the lymphangiogenesis, 16 C57BL/6 mice aged 8 weeks were given two intraperitoneal injections of incomplete Freund's adjuvant at a 15-day interval. The induced neoplasms were studied histopathologically and the neoplasms specimens were immunohistochemically examined for the expressions of VEGF-C (vascular endothelial growth factor-C) and Flt-4 (VEGFR-3, vascular endothelial growth factor receptor-3). The neoplasms were harvested and embedded in fibrin gel for culture in conditioned medium of B16-F1 cells in vitro and observed under inverted microscope. Our results showed that white solid tumor masses developed in peritoneal cavity after the induction. The tumors were confirmed to be lymphangioma by gross and histological examination. The tumor cells expressed both VEGF-C and Flt-4. Lymphatic capillaries coming from lymphangioma specimen grew into the gel and the conditioned medium of B16-F1 cells was found to be able to promote the growth of the vessels. It is concluded that intraperitoneal injection of incomplete Freund's adjuvant is a good method for inducing benign lymphangiomas in mouse and B16-F1 cells can promote lymphangiogenesis.