Gene transfer into human leukemia cell lines by electroporation: experience with exponentially decaying and square wave pulse.

The efficiency of gene transfer into human leukemia cell lines by electroporation was investigated. For both transient expression (beta-galactosidase gene) and stable transformation (neomycin resistance gene), the transfer efficiency into leukemia cell lines using a square wave pulse was superior to that using an exponentially decaying wave. The transfer rate of pMoZtk (containing beta-galactosidase gene) into K562 by electroporation using a square wave was approximately 5%, compared with 1% by an exponentially decaying pulse. Whereas the transfer rate of pMAM-neo into K562 by electroporation using an exponentially decaying pulse was less than 10(-5), a square wave generated much more efficient introduction rate of nearly 10(-3). In the other leukemia cell lines also, some square wave yields were better than exponential yields and all square wave yields were at least as good as the exponential yields.