Early interactions of cancer cells with the microvasculature in mouse liver and muscle during hematogenous metastasis: videomicroscopic analysis

Abstract

Biomechanical interactions of cancer cells with the microvasculature were studied using high resolution intravital videomicroscopy. We compared initial arrest of murine B16F10 melanoma and D2A1 mammary carcinoma cells fluorescently labelled with calcein-AM, in low pressure (liver) vs high pressure (cremaster muscle) microvascular beds. Cells were arrested due to size restriction at the inflow side of the microcirculation, penetrating further and becoming more deformed in muscle than liver [median length to width ratios of 3.3 vs 1.3 for D2A1 cells, and 2.5 vs 1.2 for B16F10, at 1 min post-injection (p.i.)]. During the next 2 h many cells became stretched, giving maximum length to width ratios of 68 vs 22.1 (D2A1) and 28 vs 5.6 (B16F10) in muscle vs liver. Ethidium bromide exclusion demonstrated that over 97% of the cells maintained membrane integrity for > 2 h p.i. (In contrast, when an acridine orange labelling procedure was used, membrane disruption of B16F10 cells occurred within 15 min p.i.) Our experiments do not indicate the ultimate fate of the cancer cells, but if cell lysis occurs it must be on a time scale of hours rather than minutes. We report a process of 'clasmatosis' in cancer cells arrested in the microcirculation: large membrane-enclosed fragments (> 3 microns in diameter) became 'pinched off' from arrested cells, in both liver and muscle, often within minutes or even seconds of arrest. The significance of this process is not yet understood. In this study intravital videomicroscopy has thus provided a valuable clarification of the interactions of cancer cells with vessel walls during metastasis.

Dual-Color Imaging of Nuclear-Cytoplasmic Dynamics, Viability, and Proliferation of Cancer Cells in the Portal Vein Area

“…HCT-116-GFP-RFP cells injected into the portal vein were all dead within 12 hours. Rapid cell death was also reported by Morris et al (8). The liver may contain an innate rapid local defense for cells entering the liver portal veins.…”

“…Morris et al (8) previously described clasmatosis of cells in the liver. We could visualize this phenomenon more clearly by using bright dual-color fluorescent cancer cells with the cytoplasm labeled with RFP and the nucleus labeled with GFP.…”

“…Real-time intravital videomicroscopy analysis of liver metastases after intraportal injection of GFP-expressing cells via a mesenteric vein revealed that both metastatic LM-EGFP and nonmetastatic E2-EGFP rat tongue tumor cells arrested similarly in sinusoidal vessels near terminal portal venules (8). The nonmetastatic E2-EGFP cells were completely eliminated from the liver sinusoids within 3 days, with no solitary dormant cells.…”

“…However, a substantial number of LM-EGFP cells remained in the liver, possibly due to stable attachment to the sinusoidal wall. The LM-EGFP cells began to grow 3 to 4 days after inoculation (8).…”

The possible role of matrix metalloproteinase (MMP)-2 and MMP-9 in cancer, e.g. acute leukemia

“…These studies clarify that MMPs are involved in metastases, but in which steps of the process of metastasis do they play a role? Other techniques besides endpoint-studies in metastases research implicated that MMPs might be involved throughout the whole process of metastasis [157,[164][165][166][167][168][169][170].…”