title: Intravital dual-colored visualization of colorectal liver metastasis in living mice using two photon laser scanning microscopy.
abstract: A major challenge of cancer biology is to visualize the dynamics of the metastatic process in secondary organs at high optical resolution in vivo real-time. Here, we presented intravital, dual-colored imaging of liver metastasis formation from a single cancer cell to metastatic colonies in the living liver of living mice using two photon laser scanning microscopy (TPLSM). Red fluorescent protein expressing murine (SL4) or human (HT29) colorectal cancer cell lines were inoculated to the spleen of green fluorescent protein expressing mice. Intravital TPLSM was performed by exteriorizing and fixing the liver lobe of living mice. This was repeated several times for the long-term imaging of the same mouse. Viable cancer cells in the living liver of living mice were visualized intravitally at a magnification of over 600×. Single cancer cells were arrested within hepatic sinusoids 2 h after injection. Platelet aggregation surrounding a cancer cell was observed, indicating a phenomenon of tumor-cell induced platelet aggregation. Cancer cells were extravasated from hepatic sinusoids to the space of Disse. Protrusions of Kupffer cells surrounding a cancer cell were observed, indicating that Kupffer cells appear to phagocytose cancer cells. SL4 cells formed liver metastatic colonies with extensive stromal reaction. Liver metastases by HT29 cells were observed as a cluster of micrometastatic nodules. High-resolution, dual-colored, real-time visualization of cancer metastasis using intravital TLPSM can help to understand spatiotemporal tumor-host interactions during metastatic processes in the living organs of living animals.
authors.affiliation: Department of Gastrointestinal and Pediatric Surgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan. qouji@clin.medic.mie-u.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Yuhki
authors.initials: Y
authors.lastname: Morimoto
authors.forename: Yuji
authors.initials: Y
authors.lastname: Toiyama
authors.forename: Yoshinaga
authors.initials: Y
authors.lastname: Okugawa
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Inoue
authors.forename: Keiichi
authors.initials: K
authors.lastname: Uchida
authors.forename: Kazushi
authors.initials: K
authors.lastname: Kimura
authors.forename: Akira
authors.initials: A
authors.lastname: Mizoguchi
authors.forename: Masato
authors.initials: M
authors.lastname: Kusunoki
mesh_terms: D000818:Animals; D015179:Colorectal Neoplasms / Q000473:pathology*; D003952:Diagnostic Imaging; D049452:Green Fluorescent Proteins; D019073:HT29 Cells; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000556:secondary*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000379:methods*; D017785:Photons
chemical_list: D049452:Green Fluorescent Proteins