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 newscientist.comnews.jspOpen ↗
Comment: Solution: stop dating pigs.
Posted by Robert Karl Stonjek.