Synchronization of mouse L-cells by a velocity sedimentation technique.

Differential velocity sedimentation at unit gravity has been used to separate an asynchronous population of mammalian cells into fractions synchronized in all phases of the cell cycle. Better enrichment was obtained for G(1) and S phases than for G(2)-M phase. Electronic cell volume measurements of the fractions indicated that the separation was primarily dependent on cell size, and an experimentally determined sedimentation coefficient agreed very well with its predicted value. Sources of dispersion in the separation (including the contribution of cell density heterogeneity) were quantitated and found to be insufficient to explain all of the observed dispersion. Both the limitations and the applications of the technique are discussed.