Imaging the Governing Step of Metastasis in Gelfoam^® Histoculture

Distant organ colonization by cancer cells is the governing step of metastasis. We review in this chapter the modeling and imaging of organ colonization by cancer cells in Gelfoam^® histoculture. ANIP 973 lung cancer cells expressing green fluorescent protein (GFP) were injected intravenously into nude mice, whereby they formed brilliantly fluorescing metastatic colonies on the mouse lung. The seeded lung tissue was then excised and incubated in the three-dimensional Gelfoam^® histoculture that maintained the critical features of progressive in vivo organ colonization. Tumor progression was continuously visualized by GFP fluorescence of individual cultures over a 52-day period, during which tumor colonies spread throughout the lung. Organ colonization was selective in Gelfoam^® histoculture for lung cancer cells to grow on lung tissue, since no growth occurred on histocultured mouse liver tissue. The ability to support selective organ colonization in Gelfoam^® histoculture and visualize tumor progression by GFP fluorescence allows the in vitro study of the governing processes of metastasis.