Water droplets produced by electrospray render cells permeable to
external DNA.
Genetically engineered products have
become indispensable. For example, genetically modified bacteria produce
human insulin. In future, gene therapy should make it possible to
introduce genes into the cells of a diseased organism so that they can
address deficiencies to compensate for malfunctions in the body. In
order for this to work, foreign (or synthetic) DNA must be introduced
into host cells, which is not exactly a trivial task. Japanese
researchers have now developed a method which could represent a true
alternative to conventional processes. As described in the journal
Angewandte Chemie, the cells are �bombarded� with water droplets
produced and accelerated by electrospray.
There are several methods to transfer DNA into a host cell. In the
simplest case the foreign DNA forces its way into the cell through a
cell membrane that has been made porous, through treatment with
electrical current or UV lasers, for example. Viruses and liposomes
can be used as genetic transporters and the genetic material can be
injected or shot into the cell with a �particle gun�. These methods
all have the disadvantage of either severely damaging delicate cells
or of being markedly expensive and complicated.
A team at the Saitama University led by Takafumi Sakai, in cooperation
with Kazuto Ikemoto (Mitsubishi Gas Chemical Company), has now
developed a methodology that could provide an alternative: They
�bombard� the cells with tiny electrically charged water droplets. The
droplets tear tiny holes in the cell membranes, through which external
DNA molecules can enter. After about one minute, the holes have closed
back up and even delicate cells survive the procedure undamaged.
This method is based on a technique called electrospray, which has
long been used with success, particularly in mass spectrometry. In
this process, the tip of an extremely fine steel capillary is put
under a high voltage. A highly charged drop of water exits the
capillary and is atomized into many micro- or nanoscopic droplets.
These charged microdroplets are strongly accelerated in an electrical
field�toward the plate holding the cell culture.
The advantage of this new method: It is suitable for a large variety
of cell types - mammalian cell cultures and
bacteria, as well as living tissue, as was demonstrated with bird
embryos. No cytotoxic reagents that could damage the cells are needed;
only pure water or a cell-tolerated saline solution are used. An
entire plate of cell cultures can be �sprayed� bit by bit, or a
specific point on some tissue can be targeted. The equipment needed is
simple, inexpensive, and portable.
Further Information
and Source:
-
Yusuke Okubo, Kazuto Ikemoto, Dr., Kanako Koike, Chihiro Tsutsui,
Ichiro Sakata, Dr., Osamu Takei, Dr., Akihito Adachi, Dr., Takafumi
Sakai, Prof.: DNA Introduction into Living Cells by Water Droplet Impact with
an Electrospray Process.
In: Angewandte Chemie International Edition, published
online: 18 Jan 2008;
doi: 10.1002/anie.200704429.
