Forced adhesive growth of K562 leukemic cells that normally grow in suspension induces variations in membrane lipids and energy metabolism: a proton NMR study.

Abstract

The mechanisms responsible for the adhesion of cells onto a material's surface and the effects that that adhesion may have on cell structure and function are fundamental questions in biomaterials research. We recently demonstrated that the erythroleukemic cell line K562, which normally grows in suspension, can be induced to grow attached to a polylysine-coated solid surface in an anchorage-dependent manner. In this study, the effects of the growth of K562 cells onto polylysine were further investigated utilizing 500 MHz 1H-NMR spectroscopy. The NMR results showed that when K562 cells are grown attached to a positively-charged polylysine surface, there are alterations in lipids and energy metabolism. In particular, there was a 31% increase in phosphatidylcholine and a 15% decrease in each of its two precursors, glycerophosphatidylcholine and choline, as well as a 20% increase in CH2 lipids and a 7% decrease in CH3 lipids in treated cells compared to the controls. These results suggest that adhesive growth can induce strong variations in membrane structure, including the membrane fluidity of K562 cells. In addition, in cells attached to polylysine there was about a 10% decrease in creatine (together with phosphocreatine), a 20% increase in gamma-glutamate, a 15% increase in beta-glutamate, and a 24% decrease in lactate. This second set of results, which is closely related to energy metabolism, indicates that not only does adhesive growth induce changes in K562 cell membrane structure, but also in the utilization of energy in these cells. The data are discussed in view of the possible role played by surface charge in affecting cell structure and function in cells that come into direct contact with charged biopolymers.