In vivo time-course imaging of tumor angiogenesis in colorectal liver metastases in the same living mice using two-photon laser scanning microscopy

In vivo real-time visualization of the process of angiogenesis in secondary tumors in the same living animals presents a major challenge in metastasis research. we developed a technique for intravital imaging of colorectal liver metastasis development in live mice using two-photon laser scanning microscopy (tplsm). we also developed time-series tplsm in which intravital tplsm procedures were performed several times over periods of days to months. red fluorescent protein-expressing colorectal cancer cells were inoculated into the spleens of green fluorescent protein-expressing mice. first- and second-round intravital tplsm allowed visualization of viable cancer cells (red) in hepatic sinusoids or the space of disse. third-round intravital tplsm demonstrated liver metastatic colonies consisting of viable cancer cells and surrounding stroma with tumor vessels (green). in vivo time-course imaging of tumor angiogenesis in the same living mice using time-series tplsm could be an ideal tool for antiangiogenic drug evaluation,reducing the effects of interindividual variation. copyright © 2012 koji tanaka et al.