Pig-human chimeras contain cell surprise
13:42 13 January 04

Pigs grown from fetuses into which human stem cells were injected have
surprised scientists by having cells in which the DNA from the two species
is mixed at the most intimate level.

It is the first time such fused cells have been seen in living creatures.
The discovery could have serious implications for xenotransplantation - the
use of animal tissue and organs in humans - and even the origin of diseases
such as HIV.

The adult pigs that had received human stem cells as fetuses were found to
have pig cells, human cells and the hybrid cells in their blood and organs.

"What we found was completely unexpected. We found that the human and pig
cells had totally fused in the animals' bodies," said Jeffrey Platt,
director of the Mayo Clinic Transplantation Biology Program

Nuclear mix

The hybrid cells had both human and pig surface markers. But, most
surprisingly, the hybrid cell nuclei were found to have chromosomal DNA that
contained both human and pig genes. The researchers found that about 60 per
cent of the animals' non-pig cells were hybrids, with the remainder being
fully human.

Importantly, the team also found that porcine endogenous retrovirus (PERV),
which is present in almost all pigs, was also present in the hybrid cells.
Previous laboratory work has shown that while PERVs in pig cells cannot
infect human cells, those in hybrid cells can. The discovery therefore
suggests a serious potential problem for xenotransplantation.

The work also suggests a possible route of infection for other viruses that
have crossed from animals to humans.

"Perhaps HIV managed to jump from primates to humans through infected blood
from a bite, which allowed the stem cells from the two species to fuse,"
Platt told New Scientist. "When the genes recombined, perhaps the virus was
reawakened."

Read the rest at New Scientist
http://www.newscientist.com/news/news.jsp?id=ns99994558

Comment:
Solution: stop dating pigs.

Posted by
Robert Karl Stonjek.
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