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Pancreas in Disguise
Scientists force liver cells to make insulin
By Serena Gordon
MONDAY, Oct. 25 (HealthSCOUT) -- It may sound like science fiction, but researchers have discovered a way to genetically alter liver cells so they produce insulin, with the hope that the cells can some day be used to treat patients with severe diabetes.
Ordinarily, insulin is produced in the pancreas and keeps blood sugar at safe levels. The researchers at the Medical College of Virginia in Richmond are trying to manipulate the cells further so that they will only release insulin in response to rising blood sugar levels.
"This is potentially a very exciting development; however, much needs to be done before one can hope to extend this to patient trials," says Dr. Bruce Zimmerman, president of the American Diabetes Association. "Unregulated release of insulin from liver cells would be worthless. The insulin release must appropriately respond to the blood glucose level before it would be of any benefit at all. Thus, this is an avenue that should be pursued, but we must be very careful not to raise false hopes at this stage."
Dr. Robert Fisher, director of the Liver Transplantation Program at the Medical College of Virginia and the lead researcher on this study agrees: "We're just beginning work on the small animal model. Our hope is that we'll be able to get baseline control of blood sugar in the small animal model, then move on to a large animal model and, hopefully, then in humans. Our expectation is that in another three years we'll be able to move to the next size larger animal model."
Fisher and his colleagues incorporated the gene for insulin into liver cells and then tricked the liver cells into changing the inactive form of insulin (proinsulin) into active insulin, the form that processes glucose. The researchers hope to create "factories" of glucose-regulating cells in the liver to maintain consistent blood sugar levels.
Working with liver cells offered the researchers several advantages. They are the only cells in the body that continually replicate and regenerate, and they are not susceptible to diabetes, the autoimmune disease that destroys the insulin-producing cells in the pancreas. Liver cells also have an enzyme that converts inactive substances into their active form, which is how researchers were able to produce biologically active, mature insulin from the cells. Also. liver cells already have a glucose response mechanism.
Fisher says one of the first tests of the genetically engineered liver cells could be in a diabetic patient who also has liver disease and is awaiting a liver transplant. Fisher says it might be possible to use liver cells rather than a whole organ transplant, but again he emphasizes, "We still have a lot of work to do. This is not something [diabetics] can get tomorrow."
What To Do
As the researchers say, this is very experimental and won't be available for diabetics for a long time -- if ever.
For more information on treating diabetes and maintaining healthy blood sugar levels, check the
For more information on treating diabetes and maintaining healthy blood sugar levels, check the American Diabetes Association or the Juvenile Diabetes Foundation.Popular Science (February 1999)
Anger in a Can FEELING UPSET? Aggressive? A bit moody? Could be your carpet cleaner. Or your car wax. Or your weed killer. Or not. That's what the EPA is trying to figure out. The agency recently introduced a program to screen 15,000 common manmade chemicals--many of which you have in your home--ensure that they aren't making you feel lousy. These potential intruders, called endocrine disrupters, are found in cosmetics, pesticides, solvents, plastics, and waxes. By interfering with the body's natural hormone balance, they alter behavior of people and animals. In addition, they can affect fertility, growth, and development. The testing is set to begin this summer or fall, says John Haley, senior director for molecular biology at OSI Pharmaceuticals in Uniondale, New York, where the first tests are being designed. After the initial screening, chemicals that are deemed to have high potential to affect human behavior will undergo more rigorous testing. --by Christopher Morrison
