Angiogenesis in high- and low-metastatic mammary tumors an intravital microscopic study

Transplantable mammary tumor lines have been established in nude mice. The high-metastatic (Met-1) line gave rise to detectable pulmonary metastasis (80%; n=39) and differed significantly (P<0.001) from the low-metastatic (Db-7) line (18%; n=22) Computer-assisted intravital microscopy was used to objectively study intratumoral angiogenesis, vascular morphometry, flow and tortuosity characteristics. The microvascular development of the two lines differed in organization (branching, pattern, distribution), however, vessel/venual diameter (range=65-110 (im) and flow velocity (range=0.2-2.7 mm/s) in both lines were measured to be nearly identical Significant intratumoral vessel tortuosity existed inside Met-1, and the tumor vessel tortuosity index (shortest distance between vessel ends/actual vessel length) of Met-1 (range=0.25-0.47; mean=0.39) differed significantly (P<0.001) from Db-7 (range=0.56-0.92, mean=0.81 ). The intratumoral tortuosity and microvascular patterns of Met-1 and Db-7 have been compared with angiogenic microvessel density (MVD) measured in tx-actin stained sections of the tumors Tortuosity and microvascular patterns are unique intratumoral features and can be used to explain the MVD hoi spots identified for human breast cancer prognosis.