More new developments from the people (PPL) that brought you dolly. Got to give these people credit for great pr.
LONDON (AP) - The laboratory where the cloned sheep Dolly was created says it has used a similar method to produce a lamb - this one named Polly - with a human protein gene.
The latest development, in which five lambs were produced, is apparently the first time the cloning technique used to generate Dolly has been successfully replicated. It also is the first case in which animals have been cloned from cells taken from living adult animals.
The five lambs were all born carrying additional genes but only one, named Polly, was given the human gene.
Animals with human genes, including pigs, have been fabricated before. But the use of the ``nuclear transfer'' technique is a step toward achieving more efficient production of proteins that could be used to treat human disease and injury, a spokesman for PPL Therapeutics said Thursday.
Scientists at The Roslin Institute in Edinburgh, Scotland, announced in February that they had cloned an adult mammal for the first time, producing Dolly. The scientists used cells from the udder of a dead sheep.
In the new experiment, the five lambs were produced by PPL and the Roslin Institute. Researchers slipped human genetic material into the nuclei of cells from sheep. These cells were then inserted into sheep's eggs from which the DNA genetic coding had been removed.
The resulting embryos were transplanted into sheep. Blood samples taken from the resulting lambs confirmed the presence of added genes.
Producing a human protein in animals by inserting a human gene is not new. Such proteins are already produced in the milk of animals that received human DNA before birth.
But DNA is normally introduced into a fertilized egg, explained the PPL spokesman, Chris Gardner. In the new procedure, the DNA was introduced instead into fibroblast cells - specialized cells like those in organs.
This, said American physiologist Robert H. Foote, is significant because fertilized eggs are in shorter supply and the use of more common fibroblast cells would greatly increase efficiency and likelihood of success.
``Through this procedure, scientists can use a few animals that can produce proteins useful in human medicine, to treat burns, etc.,'' said Foote, emeritus professor of animal physiology at Cornell University in Ithaca, N.Y.
``They have taken the next step toward the ultimate goal, which is to produce genetically engineered sheep producing efficiently high levels of proteins for pharmaceutical or clinical use,'' said Colin Stewart, an embryology developmental biologist connected with the U.S. National Cancer Institute.
In a PPL statement Thursday, the company's research director, Dr. Alan Colman, said, ``These lambs are the realization of our vision to produce instant flocks or herds which express (produce) high concentrations of valuable therapeutic proteins very quickly.''
``Until now,'' PPL's statement said, ``techniques such as microinjection allowed only the introduction of new genetic material into an animal.''
Using nuclear transfer, it said, ``more subtle modifications can be performed during cell culture, including the replacement of animal genes with the equivalent human gene.''
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