NEW YORK, NY -- A study by Columbia researchers suggests that cells in the patient's intestine could be coaxed into making insulin, circumventing the need for a stem cell transplant. Until now, stem cell transplants have been seen by many researchers as the ideal way to replace cells lost in type I diabetes and to free patients from insulin injections.
The research--conducted in mice--was published 11 March 2012 in the journal Nature Genetics.
Type I diabetes is an autoimmune disease that destroys insulin-producing cells in the pancreas. The pancreas cannot replace these cells, so once they are lost, people with type I diabetes must inject themselves with insulin to control their blood glucose. Blood glucose that is too high or too low can be life threatening, and patients must monitor their glucose several times a day.
A longstanding goal of type I diabetes research is to replace lost cells with new cells that release insulin into the bloodstream as needed. Though researchers can make insulin-producing cells in the laboratory from embryonic stem cells, such cells are not yet appropriate for transplant because they do not release insulin appropriately in response to glucose levels. If these cells were introduced into a patient, insulin would be secreted when not needed, potentially causing fatal hypoglycemia.
The study, conducted by Chutima Talchai, PhD, and Domenico Accili, MD, professor of medicine at Columbia University Medical Center, shows that certain progenitor cells in the intestine of mice have the surprising ability to make insulin-producing cells. Dr. Talchai, who works in Dr. Accili's lab, is a New York Stem Cell Foundation-Druckenmiller Fellow.
The gastrointestinal progenitor cells are normally responsible for producing a wide range of cells, including cells that produce serotonin, gastric inhibitory peptide, and other hormones secreted into the GI tract and bloodstream.
Drs. Talchai and Accili found that when they turned off a gene known to play a role in cell fate decisions--Foxo1--the progenitor cells also generated insulin-producing cells. More cells were generated when Foxo1 was turned off early in development, but insulin-producing cells were also generated when the gene was turned off after the mice had reached adulthood.
"Our results show that it could be possible to regrow insulin-producing cells in the GI tracts of our pediatric and adult patients," Dr. Accili says.
"Nobody would have predicted this result," Dr. Accili adds. "Many things could have happened after we knocked out Foxo1. In the pancreas, when we knock out Foxo1, nothing happens. So why does something happen in the gut? Why don't we get a cell that produces some other hormone? We don't yet know."
Insulin-producing cells in the gut would be hazardous if they did not release insulin in response to blood glucose levels. But the researchers say that the new intestinal cells have glucose-sensing receptors and do exactly that.
The insulin made by the gut cells also was released into the bloodstream, worked as well as normal insulin, and was made in sufficient quantity to nearly normalize blood glucose levels in otherwise diabetic mice.
"All these findings make us think that coaxing a patient's gut to make insulin-producing cells would be a better way to treat diabetes than therapies based on embryonic or iPS stem cells," Dr. Accili says. The location of the cells in the gut may also prevent the diabetes from destroying the new insulin-producing cells, since the gastrointestinal tract is partly protected from attack by the immune system.
The key to turning the finding into a viable therapy, Dr. Accili says, will be to find a drug that has the same effect on the gastrointestinal progenitor cells in people as knocking out the Foxo1 gene does in mice. That should be possible, he says, since the researchers found that they could also create insulin-producing cells from progenitor cells by inhibiting Foxo1 with a chemical.
"It's important to realize that a new treatment for type I diabetes needs to be just as safe as, and more effective than, insulin," Dr. Accili says. "We can't test treatments that are risky just to remove the burden of daily injections. Insulin is not simple or perfect, but it works and it is safe."
Additional contributors are Shouhong Xuan (CUMC), Tadahiro Kitamura (Gunma University, Maebashi, Japan), and Ronald A DePinho (Harvard Medical School).
The research was supported by the NIH (DK58282, DK64819, DK63608), the New York Stem Cell Foundation, and the Russell Berrie Foundation.
The authors report no financial or other conflict of interest.
Upon its official opening in October 1998, the Naomi Berrie Diabetes Center at Columbia University Medical Center established a new standard of care for the 1.6 million people with diabetes in the New York area--combining world-class diabetes research and education programs with unprecedented family-oriented patient care. Named for the mother of the late Russell Berrie, founder of RUSS™ Toys, the center is today recognized as the most comprehensive diabetes research and treatment center in the tri-state region and has been designated a national "Diabetes Center of Excellence" - one of only three in the state of New York. Approximately one hundred faculty and students, affiliated with the Center, conduct basic and clinical research related to the pathogenesis and treatment of all forms of diabetes and its complications. For more information, visit www.nbdiabetes.org.
Columbia University Medical Center provides international leadership in basic, pre-clinical and clinical research, in medical and health sciences education, and in patient care. The medical center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the College of Physicians and Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. Established in 1767, Columbia's College of Physicians and Surgeons was the first institution in the country to grant the M.D. degree and is among the most selective medical schools in the country. Columbia University Medical Center is home to the largest medical research enterprise in New York City and state and one of the largest in the United States. For more information, please visit www.cumc.columbia.edu.