Diabetes Cured in Mice with Novel Immune System Approach

Researchers have achieved a significant milestone in the fight against type 1 diabetes, successfully curing the disease in mice without the need for long-term immune suppression. The study, detailed in the January issue of Science, demonstrates a novel approach to islet transplantation by creating a blended, or “chimeric,” immune system.

Understanding Type 1 Diabetes and Current Challenges

In type 1 diabetes, the body’s immune system mistakenly attacks and destroys insulin-producing islet cells in the pancreas. This leads to a lifelong dependence on insulin injections. While islet transplantation offers a potential cure, it traditionally requires patients to take powerful immunosuppressant drugs indefinitely to prevent the body from rejecting the transplanted cells. These drugs have significant side effects and limit the widespread applicability of the treatment.

The 'Chimeric' Immune System: A New Strategy

The research team developed a method to create a chimeric immune system, combining elements of both the recipient’s and the donor’s immune systems. This allows the recipient to tolerate the transplanted insulin-producing cells without the need for continuous immune suppression.

How the Process Works

The process involves transplanting bone-marrow stem cells and islet cells from the same donor into the recipient mouse. A carefully calibrated “conditioning” process, utilizing antibodies, low-dose radiation, and the rheumatoid arthritis drug baricitinib, creates space in the recipient’s bone marrow for the donor stem cells. This allows the donor stem cells to mature and “educate” the recipient’s immune system to accept the foreign tissue.

“If you have a mixture of donor and recipient, the donor’s immune system – the blood system – can influence the behavior of the recipient,” explained Dr. Shizuru, lead researcher on the study.

Promising Results and Future Outlook

The mice treated with this method were still producing insulin 20 weeks after the transplant, and analysis showed their immune systems were functioning well without signs of rejection. The process took approximately 12 days, and the radiation dose was lower than typically used in bone-marrow transplants.

Expert Commentary

“It does represent, in theory, a big step forward,” said Dr. DiPersio, an oncologist at Washington University in St. Louis who was not involved in the study. However, she cautioned that significant hurdles remain before this treatment can be applied to humans.

These challenges include finding approved human analogues for some of the antibodies used in the study and addressing the scarcity of donors who can provide both bone marrow and islet cells. Maintaining the immune system balance for decades, crucial for a lasting cure, also presents a significant challenge.

Study Details

The research, led by Shizuru and colleagues, involved a multistep process using antibodies, radiation, and baricitinib. The findings were published in Science, with an accompanying commentary by DiPersio. The study was authored by Bhagchandani, P., Ramos, S. A., Rodriguez, B., and others.