Comprising scientists from Tohoku University, the team said its research confirmed that injections of microRNAs resulted in the reproduction of pancreatic cells that secrete insulin, the hormone that controls blood sugar levels.
Most patients develop diabetes when pancreatic beta cells decline in number, making it impossible to secrete a sufficient amount of insulin. It has been said that it is difficult to raise the number of reduced beta cells again.
Inspired by reports that said bone marrow transplants in leukemia and other cases led to easing diabetes symptoms, Tetsuya Yamada, an associate professor of diabetes internal medicine at the university, and his colleagues examined about 40 types of microRNAs whose blood levels increase after bone marrow transplantation and identified two microRNAs that help reproduce beta cells.
“We need to see if reproduced beta cells will decline in number over time,” said Yamada. “As microRNAs can be chemically synthesized and do not require huge costs, I want to start a clinical trial in the near future.”
In its research, the team killed beta cells in six mice with a drug to cause them to contract diabetes. Then the scientists injected the two kinds of microRNAs into veins in the tails of the mice on the fifth day, eighth day and 11th day of the experiment.
On the 20th day, the team found the mice’s fasting blood glucose levels had been lowered 40 to 50 percent compared with untreated mice. Their improved glucose levels were just 1.2 times higher than those for healthy mice.
The scientists discovered the amount of insulin in the blood for the microRNAs-injected mice was double that for untreated mice. They confirmed through microscopy that the number of beta cells rose in the treated mice.
The team also added the microRNAs to beta cells cultivated in vitro and found they had the same effects outside the bodies of mice.
In a healthy animal’s pancreas, the proliferation of beta cells is regulated by a gene that controls cell proliferation. Beta cell proliferation was promoted in the experiment, likely because the activity of the gene was inhibited by the injected microRNAs, according to the researchers.
No serious side effects have been reported in bone marrow transplants, so the new diabetes treatment is expected to pose no major problems in terms of safety.
“The new method appears to be relatively simple as the technique just requires administration of microRNAs and gene modifications, and other complex procedures are not necessary,” said Shoen Kume, a stem cell biology professor at the Tokyo Institute of Technology. “Clinical applications of the technique will be easier, so I believe their finding is a groundbreaking achievement. I will watch closely to see if all reported treatment effects can be attributed to the proliferation of beta cells alone.”
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