Some problems in using density gradient centrifugation for synchronization of L5178Y-S cells

The application of sucrose gradient sedimentation for synchronization of murine lymphoma L5178Y-S cells was investigated. Centrifugation of the cells in a linear 2--10% sucrose gradient in Fischer's medium allows to obtain populations enriched in (I) young cells, (II) DNA-synthesizing cells, and (III) old cells. Population I showed highest degree of synchrony and contained at least 70% G1 cells. However, only a proportion of cells from population I progressed normally (approximately 30% of cells from this population remained in G1 during post-separation incubation). It was shown that the sucrose concentrations used for separation did not affect growth of L5178Y-S cells. On the other hand, relatively gentle mechanical treatment severely inhibited proliferation of these cells. It is suggested that excellent adaptation of cells to the culture medium and complete stability of the medium's composition are the prerequisites for a successful synchronization of L5178Y cells by gradient centrifugation.