Cell membrane maturation of Friend erythroleukemic cells and tocopherol-dependent erythropoietin effect: a scanning electron microscopic study.

Typical morphological features of surface structural alterations during Friend cells differentiation are described. Scanning electron microscopy (SEM) revealed that DMSO induction switched on cell alteration of the proerythroblast-like cells, possessing microvilli projections on cell membrane with some ruffles, to an advanced stage with a blebby surface. This was followed by the formation of a pear-like polarized cell separated into two zones by a narrow cytoplasmic bridge at the equatorial plane. The polarized cells showed a smooth surface and tended to disconnect into two unequal cells. The villous leukemic erythroblast has negatively charged sialic acid residues on the glycocalyx, available for latex hydrazide probe binding, while the blebby and polarized cells lack it. Tocopherol added to culture medium of DMSO-induced erythroleukemic cells prevented the formation of blebs and the polarization phenomena, without affecting hemoglobin synthesis. The tocopherol-treated cells contain available negative charges for latex hydrazide binding similar to uninduced Friend cells. Erythropoietin potentiated a repolarization ability and morphological alteration capacity to the tocopherol-treated cells and this was accompanied by a loss of glycocalyx-negative charges. At these growth conditions erythyropoietin induced a dose-dependent proliferation effect.