Heralding cell transplantation as a potential cure for diabetes, Gordon Weir, chair of the Research and Wellness Foundation at the Joslin Diabetes Center, spoke on the use of stem cells as a form of treatment on Tuesday before an audience in the Haldeman Center.
"I'm a little depressed we haven't cured diabetes yet," Weir said.
Weir hopes scientists make progress towards finding a cure for diabetes by researching beta cells, an insulin-producing cell located within the pancreas, he said. People with Type 1 diabetes lack beta cells and are unable to produce insulin, a hormone that controls glucose levels in the blood. Current treatment for Type 1 diabetes includes frequent injections of insulin. Weir identified beta cell replacement as a potential way to address Type 1 diabetes, provided that an adequate number of cells are harvested to meet the demand of the diabetic population and that these cells can be successfully transplanted into the pancreas.
Weir discussed the history of beta cell research, beginning with work on replacement therapy in the 1960s, when doctors completed the first successful pancreas transplant. In 1972, researchers began performing islet transplants in rats, and by the 1980s pancreas transplants were widespread in lab animals. The first serious human transplants, beginning in 1989, produced "depressing" results -- only one in 10 patients was cured and the symptoms returned within a week. In 2000, scientists developed the Edmonton Protocol, the process of extracting islets from the pancreases of human cadavers.
Current methods of transplantation are not without flaws, Weir said. At least two pancreases are needed to give insulin-producing independence to a Type 1 diagnosed individual. In addition, this independence is usually lost within two years of transplantation.
Alternate methods of producing beta cells include initiating normal beta cell development using stem cells or regeneration, a process that Weir described as "giving someone an elixir so that they grow new beta cells." So-called "xenotransplants," where beta cells are transplanted from nonhuman species such as pigs, are also being pursued, Weir said.
Beta cells for transplantation can also come from an infant's umbilical cord blood, Weir said. Many individuals often have umbilical cells preserved so they can be used if the individual develops diabetes later on. Treatment using these cells avoids the side effects of other transplantation options because the body's immune system does not target the cells for attack as foreign infiltrates.
Weir cited a recent study by Novocell, a San Diego-based biotechnology company, as evidence of significant progress in beta cell replacement therapy. Scientists injected precursor beta cells into 105 mice hoping the premature cells would develop into full beta cells that could conceivably be transplanted to humans. The researchers found that the beta cells matured completely and cured the mice of diabetes after 90 days, though seven mice developed benign tumors. Despite concern about how readily the process can be applied to humans, the experiment represents a major step towards the achievement of beta cell replacement therapy, Weir said.
Dartmouth's Student Society for Stem Cell Research organized Weir's lecture.
