Abstract
In this study, tumor blood vessels were examined during the proliferation of VX2 carcinoma, and the effects of the antifibrinolytic agent, tranexamic acid, on tumor growth and vascularization were investigated.
Materials and methods.
VX2 carcinoma cells were implanted into rabbit ears, and the rabbits were divided into two groups. Experimental group: tranexamic acid (2, 000 mg/kg) was given daily by femoral intramuscular administration for 14 days. Control group: tranexamic acid was not administered. Gross, histologic, scanning electron microscopic of microvasculature casts and ultrastructural observations were performed in each group 3, 5, 7 and 14 days after tumor implantation.
Results.
1. Grossly, tumor growth was suppressed in the experimental group compared with the control group throughout the experimental period.
2. Histologically, in the control group, tumor cells proliferated invasively with the formation of stroma and small tumor nests. In contrast, in the experimental group, tumor cells proliferated densely with little infiltration and small amounts of stroma were formed from early after tumor implantation.
3. Regarding the microvascular structure, in the control group, active angiogenesis of the tumor was found 3 days after tumor implantation. New capillaries and new sinusoidal capillaries sprouting from the vessels of the surrounding tissue extended to the tumor center after 5 days. Dense capillary networks were formed throughout the entire tumor region after a week, but capillaries were not found in the central area of tumor because of necrosis after 2 weeks.
4. In the experimental groups, tumor angiogenesis was delayed compared with the control. Angiogenesis was observed after 5 days, and new capillaries extended to the tumor center and anastomosed with each other; sparse capillary networks were formed after a week. Capillary networks were formed throughout the entire tumor region after 2 weeks, but were not as dense as the control. Ultrastructural observations by transmission electron microscopy demonstrated that some endothelial cells were immature compared with the control.
