Cloned pigs give vital boost to future of transplants  The first
experimental operations to implant cells and organs from
genetically modified pigs into people could be only four years
away after the birth of a litter of cloned piglets marked a
breakthrough in the field of animal to human transplants.  The
piglets were born in Virginia on Christmas Day at a centre run
by a US subsidiary of the Edinburgh-based biotech company, PPL
Therapeutics, but PPL announced the birth only yesterday.  David
Ayares, head of research at PPL's US lab, said the new litter -
christened Noel, Angel, Star, Joy and Mary - represented "a
critical milestone" in the effort to realise animal to human
transplants, known as xenotransplantation. "This advance
provides a near term solution for overcoming the shortage of
human organs for transplants as well as insulin-producing cells
to cure diabetes," he said.  The cloned animals are the world's
first "knockout" pigs, meaning that scientists have zoomed in on
a single one of the tens of t