Assessment of Angiogenesis and Tumor Growth in Conscious Mice by a Fluorimetric Method

Abstract

Angiogenesis and tumor growth in conscious mice have been determined using the kinetics of appearance of a fluorescent tracer in the bloodstream after application to subcutaneously implanted sponges bearing tumor cells. The functional parameter expressed in terms of half-time (t1/2; time taken for the fluorescence to reach 50% of the peak in the systemic circulation), which is inversely proportional to blood flow, showed that in the tumor-free implants t1/2 values decreased from 11.55 ± 1 min at day 1 to 5.7 ± 0.44 min by day 14. In the tumor-bearing implants, this process was accelerated and maximum vascularization was achieved by day 7 (3 days after tumor cell inoculation). Increases in t1/2 values were observed at days 10 and 14, which paralleled the tumor growth as indicated by wet weight. The hemoglobin content (μg Hb/mg wet weight) in the tumor-free group increased during the 14-day period. In contrast, in the tumor-bearing implants. Hb concentration decreased per unit of tissue weight. Dexamethasone treatment for 13 days prevented fibrovascular tissue infiltration in tumor-free implants, but was unable to delay tumor growth, indicating that this procedure can be used to exclude the inflammatory reaction induced by the implantation technique, thus allowing tumor angiogenesis to be studied without the confounding influence of the host inflammatory cells. The results of our experimental observation indicate the suitability of this combination of techniques for analyzing angiogenesis induced by tumor cells and several hemodynamic features of Ehrlich tumor growth in awake animals.