ALTERING THE BIOCHEMICAL STATE OF INDIVIDUAL CULTURED-CELLS AND ORGANELLES WITH ULTRAMICROELECTRODES

We describe an efficient technique for the selective chemical and biol ogical manipulation of the contents of individual cells. This techniqu e is based on the electric-field-induced permeabilization (electropora tion) in biological membranes using a low-voltage pulse generator and microelectrodes. A spatially highly focused electric field allows intr oduction of polar cell-impermeant solutes such as fluorescent dyes, fl uorogenic reagents, and DNA into single cells. The high spatial resolu tion of the technique allows for design of, for example, cellular netw ork constructions in which cells in close contact with each other can be made to possess different biochemical, biophysical, and morphologic al properties. Fluorescein, and fluo-3 (a calcium-sensitive fluorophor e), are electroporated into the soma of cultured single progenitor cel ls derived from adult rat hippocampus. Fluo-3 also is introduced into individual submicrometer diameter processes of thapsigargin-treated pr ogenitor cells, and a plasmid vector cDNA construct (pRAY 1), expressi ng the green fluorescent protein, is electroporated into cultured sing le COS 7 cells, At high electric field strengths, observations of dye- transfer into organelles are proposed.