Centrifugal elutriation and characterization of tumor cells from venous blood of tumor-bearing mice: possible relevance to metastasis.

Centrifugal elutriation was applied to separate blood-borne tumor cells using three mouse tumor systems, NFSA2ALM1, FSA1231, and FSA1233, syngeneic to C3H/HeJ mice. The tumor cells separated from venous blood were further characterized regarding cell cycle stage (DNA content), cell size, and clonogenicity in vitro. The majority of the blood-borne tumor cells were in G1 phase and dead or dying (not "clonogenic"). Clonogenic tumor cells were very few, e.g., 1.7 per mouse (NFSA2ALM1 bearing) or 0.3 per mouse (FSA1231 bearing) (i.e., a few clonogenic tumor cells of 10(8) blood-borne nucleated cells). The higher number of clonogenic blood-borne tumor cells of NFSA2ALM1 over FSA1231 was consistent with the clonogenic tumor cell release rates reported previously and paralleled spontaneous lung metastasis efficiencies of these tumors.