Preparative Electrophoresis of Living Mammalian Cells in a Stationary Ficoll Gradient

An apparatus was designed for the vertical density-gradient electrophoresis of viable mammalian cells. Cultured Chinese hamster cells (M3-1F3) were grown is suspension and layered on top of a 0-10% ficoll gradient which was also an inverse 6.8-5.1% sucrose gradient in phosphate buffer, pB 7.2 and 1Z glucose. A 60-ml vertical gradient of this composition covered the density range 1.04-1.05 g/cm 3 over a distance of 15 cm in a 2.3 cm diameter glass column. An electric field of approximately 2.3 V/cm was applied for 5 hr. The cells migrated 4.7 cm during this period. The migration rate was consistent with the cells having an electrophoretic mobility of -1.15 ± 0.20 μm/sec per volt/cm, equal to that determined by microelectrophoresis. The gradient was harvested in 50 fractions after electrophoresis, and the viability of the cells was 75% on the basis of colony formation.