| Thu Aug 28, 2:28 PM ET
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - In a move that could make producing drugs almost as easy as brewing beer, U.S. scientists said on Thursday they had figured out how to use yeast to make vital human proteins.
The scientists hope the technology can be put to work producing human proteins in large quantities and make it possible to use as drugs proteins that now cannot be mass-produced.
Therapeutic proteins include insulin, blood factors that treat hemophilia, proteins used to boost the blood cells of cancer patients and multiple sclerosis drugs.
Experimental proteins are in the works that could treat cancer and help patients with genetic diseases including cystic fibrosis. In theory, any disease that has a faulty gene as its basis could be treated with a therapeutic protein.
"This technology has the potential to revolutionize the way therapeutic proteins are made -- better, cheaper, faster, safer -- and offer a level of control over the quality of the end product that has never existed before," said Tillman Gerngross, associate professor of biochemical engineering at Dartmouth College who helped lead the study.
Gerngross is also chief scientific officer at GlycoFi, a privately held company in Lebanon, New Hampshire, that he helped found to develop and exploit the technology.
Some human proteins, such as insulin, can be made cheaply now using bacteria. The bacteria are simply genetically engineered to make the protein.
But this process only works with some proteins, Gerngross said.
Most human proteins are covered with complex sugar molecules in a process known as glycosylation. Bacteria such as E. coli cannot glycosylize in a human pattern.
"About 70 percent of all therapeutic proteins have sugars attached to them," Gerngross said in a telephone interview.
These have to be made using batches of cells from mammals, called mammalian cell lines. They are expensive, difficult to maintain and carry the threat of transferring animal retroviruses to the human protein.
"They take a very long time to produce a protein -- two to three weeks, where yeast takes three to four days," Gerngross said.
Writing in the journal Science, Gerngross and his colleagues said they added five human genes to the yeast Pichia pastoris, making it into a human protein machine.
"We have essentially been able to humanize the yeast," he said. "The process time is shorter and yield much, much higher."
Gerngross and colleagues, who have patented their process, now are taking on the production of therapeutic proteins directly, and selling the technology to other biotech firms that make proteins.
It may be possible to make existing products more cheaply and Gerngross said his company may be able to patent the process and make the equivalent of a generic version of an expensive protein-based treatment.
Gerngross believes his technology is more precise and safer than cell-based methods.
The process will also challenge the fledgling industry of bioengineered animals. Goats, sheep, rabbits and cows have all been genetically engineered to make human proteins in their milk. | |
