Replies to post #4614 on GTC Biotherapeutics (fka GTCB)

[poorgradstudent]

Without knowing exactly how they do the purification, I can tell you that DNA is rather trivial to remove from suspensions using standard ion exchange chromatography methods.

In any case, whatever gets through will be inconsequential as humans already have some DNA circulating in their bloodstream, and there is significant DNase activity in the blood.

* DNase is the enzyme that degrades DNA. In fact, many lab purification methods will employ DNase to rid protein suspensions of DNA. In the case of GTCB, I'm not sure if they add a DNase step... it would not be how I would do it, as you would be adding a protein contaminant during the purification of another protein.

[floblu14]

Might this help, OKY -

>Tangential flow filtration is an initial product recovery step that removes fats and other colloidal proteins such as casein from milk containing the target protein of interest. This approach also allows for the significant reduction in volume of the milk while yielding a material that can be aseptically processed. The resulting partially purified intermediate bulk product is more stable than unprocessed milk and can be stored for extended periods either refrigerated or frozen. The intermediate bulk product is then taken through additional purification steps, typically chromatography, to obtain a highly purified form of the desired therapeutic protein.<

http://www.transgenics.com/pressreleases/pr080105.html

[croumagnon]

"Although the filtration process is super. There is an
infinitesimal amount of goat DNA, fragments, small chaines
that do get transfused into the patient."

You already had two good answers from PGS and floblu. However, your question goes to the core of what makes people nervous about transgenics. In short, the concept of mixing the DNA's of animals into humans is a scary one.

The real question is how "infinitesimal" is that amount of DNA transference, if any, and can it down the line create problems for these patients. I do not know the exact answer to that but I recall that it had been discussed previously and it was "determined" to be really infinitessimal and of no consequences to humans... As I recall, the thinking was that you would get more such transferrence by simply drinking regular goat milk, or eating goat, than you would get from ATryn... Of course, this argument only goes so far because our digestive tracks are equipped to deal with such matters but transfusions bypass all these defense mecahnisms. Perhaps I am cluelesss here but that is my recollection and that used to be a mojor concern of mine regarding GTCB and it is still somewhat of a concern...