From Wikipedia,
the free encyclopedia.
Electroporation, or
electopermeabilization, is a
significant increase in the
electrical conductivity and
permeability of the
cell plasma membrane caused by
externally applied
electrical field. It usually
used in
molecular biology as a way of
introducing some substance inside
the cell: by loading it with a
molecular probe, bring in a drug
that can change cell's function,
or a piece of coding
DNA.
This unnatural increase in
permeability is theoretically
explained as a process of
formation of very small openings
(pores) in the plasma membrane. If
the strength of electrical field
and duration of exposure to it are
properly chosen, the pores formed
by the electrical pulse reseal
after a short period of time,
during which the extracellular
compounds have a chance to get
inside the cell. However,
excessive exposure of live cells
to electrical fields can also
cause
apoptosis and/or
necrosis -- the processes that
result in cell death. Such harsh
treatments are used for killing
tumor cells.
In molecular biology, the
process of electroporation is used
for the
transformation of
bacteria or plant protoplasts.
In addition to the lipid
membranes, bacteria also have
cell walls which are different
from the lipid membranes and are
made of cellulose and its
derivatives. However, the
cellulose walls are naturally
porous, they only act as stiff
shells that protect bacteria from
severe environmental impacts. If
bacteria and
plasmids are mixed together,
the plasmid can be transferred
into the
cell after application of a
pulsed electrical field, which
causes pore formation in the
bacterial plasma membrane. Several
hundred volts across a distance of
several millimeters are typically
used in this process. Afterwards,
the cells have to be handled
carefully until they have had a
chance to divide producing new
cells that contain reproduced
plasmid. This process is usually
ten times as effective as
chemical transformation.
This procedure is also highly
efficient for the introduction of
foreign
genes in tissue culture cells,
especially
mammalian cells, or similar.
It is for instance used in the
process of producing
knockout mice, but more
importantly, for the purpose of
tumor treatment, gene therapy and
cell-based therapy.
