The Pig Cell issue:
The
main problem with xenotransplants is the fear of transferring of disease
from one species to the next. For example, the pig could have been a carrier
for a strain of influenza that killed 20 million people in 1918. However,
as far as neural xenotransplant, the main concern is porcine endogenous
retroviruses (PERV).
Positive
result that show that pig cells could pass on disease:
A
study done by Dr Ulrich Martin and colleagues from Germany shows that PERV
can be produced by cells from pig aortas, livers, lung, and skin. (Williams, Rebecca
D. 1996)
Under
laboratory conditions, Robin Weiss of the Institute of Cancer Research
in
London was able to show that two types of these viruses were able to spread from pig
cells to human cells. This shows that there is a possibility that there can be a transfer
of virus from pigs to animals. (Coghlan,
Andy 1998)
A
study by Walid Heneine and colleagues from the USA and Sweden: Here ten
patients were given 400 million to 2 billion insulin-producing cells from pigs. These
patients are also imunosuppresed and no evidence of PERV infection was found in
the blood samples. Patients that had survived for over a year showed no pig virus
DNA , did not have antibodies against pig virus, and had no sign of reverse
transcriptase enzymes. (Heneine, Walid at al. 1998)
A
study by Clive Patience and colleagues from the UK and Sweden: A transplant
in
which two kidney-failure patients received pig kindneys. In both of these patients
there was no sign of transference of PERV to the patients. (Coghlan, Andy 1998)
A
study by Diacrin, a company in Charlestown Massachusetts: Pig cells were
injected in the brain of 24 patients. Some of these people were treated 3 years prior
and none showed signs of PERV infection. (Coghlan, Andy 1998)
The procedure involving injection of pig cells into the human brain requires the passing of needles into a person's brain.
Risks
for passing a needle into the brain:
1
in 500 needle passes could result in a stroke. (Golberg, Jeff 1995)
Since
operations take about 14 to 16 needle passes, there is a 3% chance of
stroke (Golberg, Jeff 1995).
Currently there seems to be no transfer of PERV from the implanted porcine cells. However, a longer and more careful study needs to be accomplished before we can be certain that there is no transfer of disease by porcine cells. Concerning the danger of the procedure itself, there seems to be a very high risk involved. However, if this procedure proves to be successful and since Parkinson's disease is such a horrible disease, many people may accept this risk and have the treatment done.
