Posted by ali on July 19, 19103 at 11:18:22:
In Reply to: Liver Cells Genetically Altered to Produce Insulin posted by Stephanie Lau on October 15, 1999 at 11:29:31:
: Scientists have turned to a new possible solution to help treat people with type 1 or insulin-dependent diabetes: genetics.
: Researchers at the Medical College of Virginia, Richmond, have genetically altered liver cells to function as pancreatic islets -- clusters of cells in the pancreas that produce insulin, the hormone used to regulate blood sugar levels.
: The researchers, led by Dr. Robert A. Fisher, director of the liver transplantation program at Medical College of Virginia, are working to further alter the liver cells called hepatocytes so that they will release insulin in direct response to fluctuations in blood sugar levels.
: Ultimately, the researchers hope to create ``factories'' of blood sugar-regulating cells in the liver that may be used to control diabetes. The research was unveiled at the American College of Surgeons Annual Clinical Congress, held October 10 to 15 in San Francisco.
: The research showed that by genetically altering hepatocytes, the liver cells would produce mature, biologically active insulin. Fisher said that DNA of the body's inactive insulin can be read and sequenced by an enzyme and then placed into the liver, thus producing a form of active insulin. ``The idea was to fix this native enzyme to make it convert inactive insulin into the real thing,'' he said.
: Liver cells offer two strong advantages. First, unlike islet cells, they are not affected by diabetes. Second, liver cells are the only cells in the body that can continually regenerate. The scientists therefore surmised that if an insulin-producing ``factory'' can be created within the regenerating liver cells, ``that factory may stay open indefinitely.''
: The researchers have yet to test the new cells in animals, which would be the next step before moving on to clinical trials involving humans. Fisher said that the research will expand to include altering a different natural liver enzyme, in hopes that it will recognize changes in blood sugar levels. He explained that the enzyme will be tagged to the gene for human insulin. In theory, this will enable the altered liver cells to release and process the flow of insulin when blood sugar is high and turn it off when blood sugar is low.
: Fisher said that he has pursued genetic altering because type 1 diabetes is often difficult to control, as people with the disease are unable to produce insulin naturally. Blood sugar levels can be monitored with over-the-counter test kits, but as the levels in people with type 1 diabetes fluctuate often, it can be difficult to maintain levels consistently and within normal ranges. People with type 1 diabetes may need to adhere to aggressive insulin-replacement therapy, in which they have to monitor their blood sugar levels and inject themselves with insulin several times daily.
: Russ Colchamiro
: New York Times Syndicate
: c. 1999 Medical Tribune News Service