California scientists have successfully coped the genes that make insulin in rats, a breakthrough they feel could lead to easier and cheaper production of human insulin by 1979.
The development is one of the major accomplishments so far of the new "recombinant DNA" research by which scientists can insert genetic material from one species into the cells of another.
What workers at the University of California in San Francisco reported yesterday is that they are growing, or "cloning," rat insulin genes (which consist, like all genes, of deoxyribonucleic acid, or DNA) in colonies of the bacterium called E. coli.
Their hope is to isolate and grow the human insulin gene in the same way, then again use harmless strains of E. coli as factories to make almost endless supplies of insulin for diabetics.
Insulin is now extracted from cattle or pig pancreases. It is essential for thousands of diabetics, who must inject it into themselves once or twice a day to make up for the insulin their own bodies fail to produce. But insulin has sometimes been in short supply, and some diabetics develop allergic reactions to cattle or pig insulin. The body requires insulin to metabolize sugar.
The California work was reported by Professors William Rutter and Howard Goodman, whose laboratories and workers have collaborated.
Normal insulin is produced by cells called islets of Langerhans in the pancreas. The Californians used genes from rats because fresh human pancreases are hard to get, and because any such work with human DNA would have to be done in a kind of tightly sealed laboratory that does not yet exist.
Safety guidelines set by the National Institutes of Health in Bethesda specify that such work must be confined to a so-called P4 laboratory, lest some unexpectedly dangerous genes or bacteria result and cause harm.
Two P4 laboratories will be completed soon at NIH and its satellite facilities at Ft. Detrick, Md., "and if necessary we'd go to Ft. Detrick to work," Rutter said.
Some scientists have said the manufacture of insulin in laboratory factories by genetic engineering is five to 10 years away.
"But I believe it'll be done sooner than anyone has expected," Rutter said.
The Californians' next step will be to try to induce their new mass-produced genes to actually manufacture insulin - in biological language, to make the genes express themselves.
"This is a complicated business with a lot of complicated technology, and the insulin protein goes through several stages before it is completed," Rutter said. "But I have confidence that within a year we'll have demonstrated this."
He and Goodman believe they will do still more. For their achievement includes learning much that is new about insulin genes - rats have two separate genes that do the job, not just one as in humans - as well as about insulin manufacture in animal cells.
Another benefit, Rutter said, could be "to understand what regulates gene expressions," the way genes govern cells to make every living creature and every part of the body what it is.