SELECTIVE ELECTROFUSION OF CONJUGATED CELLS IN FLOW

Using a modified flow cytometer we have induced electrofusion of K562 and L1210 cells in flow. The two cell types are stained with two diffe rent fluorescent membrane probes, DiO and Dil, to facilitate optical r ecognition, and then coupled through an avidin-biotin bridge. In the f low cytometer, the hydrodynamically focused cells and cell pairs are f irst optically analyzed in a normal flow channel and then forced to fl ow through a Coulter orifice. If the optical analysis indicates that a cell pair is present, an electric pulse is applied across the orifice to induce fusion. The pulsed cell pairs were subsequently analyzed us ing normal and confocal microscopy to evaluate fusion induction. It ap pears that fusion can be induced in about 10% of pulsed cell pairs whe n one electric pulse with a duration of 10-15 ps and an effective elec tric field strength of 4-8 10(5) V/m is used.