Transfection efficiency

[Dave Bates]

I've been wondering about how people measure their transfection
efficiency. A lot of messages here, and in papers talk about
transfection efficiencies with liposomes bvetween 20 and 40% In my
experience that was what it looked like I was getting in my cells
(endothelial cells). I started comparing different liposomes and
actually did a count of number of cells transfected as a percentage as
the total number of cells in the microscope field. The figures I came
up with though were around 8%, and the highest was 12%. I got a few
other people in the lab to estimate the efficiency and they all said
between 25 and 30% when it was actually below 10%. I've seen a couple
of papers with similar numbers of cells transfected per field - with
the cells around the same size -  saying that they were getting 40 or
even 50% transfection efficiency. I tried doing a literature search on
transfection efficiencies in endothelial cells and others and didn't
come up with anything definitive (i.e. counting cells). Does anyone
know of a reference for this sort of thing and has anybody actually
been anal enough to do their own counting.

Also if you transfect at 50% confluence, and half the cells die, then
the survivors grow back to 100% and then you assay, if you get 40% of
the cells transfected isn't the transfection efficiency only 10% (i.e.
only 1 in ten of the cells you started with transfected, which
multiplied by four times to reach confluence). Is my logic correct
here?

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Dave Bates PhD                                     Tel: 916 752-7081
Postdoctoral Researcher                            Fax: 916 758-2554 
Dept of Human Physiology                         email:
dobates at ucdavis.edu
University of California at Davis                drink: anything
Davis, California 95616, USA            No I don't have a sense of
humour 
                                                now buy me a beer      
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