Researchers at Stanford Medicine say they have developed a combination treatment method that cured or prevented type 1 diabetes in mouse models by pairing blood stem cell transplantation with pancreatic islet cell transplantation under a substantially reduced preconditioning regimen. The approach creates a mixed immune system from both donor and recipient cells, which stopped autoimmune destruction of insulin-producing cells while also producing long-term tolerance to the transplanted tissue. The findings, published in the Journal of Clinical Investigation Insight, show that reversing type 1 diabetes can be accomplished without chronic immunosuppression or the toxic conditioning via radiation or chemotherapy currently used for hematopoietic stem cell (HCT) transplantation.
“The possibility of translating these findings into humans is very exciting,” said senior author Seung K. Kim, MD, PhD, a professor of developmental biology at Stanford. “The key steps in our study—which result in animals with a hybrid immune system containing cells from both the donor and the recipient—are already being used in the clinic for other conditions. We believe this approach will be transformative for people with type 1 diabetes or other autoimmune diseases, as well as for those who need solid organ transplants.”
Type 1 diabetes is an autoimmune disease that attacks pancreatic islet cells. While islet transplantation can restore insulin production, it typically requires immunosuppressive drugs that carry risks including infection, malignancy, and organ damage. The Stanford team’s approach reduced these negative effects by inducing immune tolerance through mixed hematopoietic chimerism, a state in which donor and recipient immune cells coexist.
“Mixed hematopoietic chimerism after hematopoietic cell transplantation (HCT) can modulate the immune system and induce tolerance to allogeneic tissues,” the researchers wrote. “However, bone marrow conditioning-related toxicities preclude wider adoption of HCT for transplant allotolerance.”
The current findings by the Stanford team builds on a series of research initiatives beginning with work published in 2022, in which the researchers showed they could cure toxin-induced diabetes in mouse models using antibody-based immune conditioning combined with moderate radiation (200–300 cGy), followed by transplantation of donor-matched blood stem cells and islets. This study served as a proof of concept but used radiation at levels that are potentially toxic.
A November study published in JCI, along with the new research addressed two significant challenges for developing an effective transplantation protocol: autoimmune diabetes, in which the immune system targets islet cells, and the need to reduce conditioning toxicity. In the November study, the researchers added an immune-modulating drug used in autoimmune disease to their regimen. This change enabled the formation of a hybrid immune system that both accepted donor islets and prevented autoimmune attack. All treated mice were protected from developing diabetes, and those with already possessing the disease were cured.
To further reduce toxicity, the April study added additional agents, baricitinib, venetoclax, and an αCD47 antibody, to go with αCD117 antibody and transient T cell depletion. These agents were selected because they target distinct biological pathways involved in immune regulation and bone marrow niche clearance. Baricitinib, a JAK1/2 inhibitor, reduces inflammatory signaling and supports donor cell engraftment. Venetoclax promotes apoptosis of specific immune cells, and αCD47 disrupts a signaling pathway that normally protects cells from clearance, which helped in the removal of host stem cells to make space for donor cells.
“We systematically tested baricitinib (JAK1/2 inhibitor), venetoclax (Bcl2 inhibitor), and αCD47 antibody, agents in current clinical use, and quantified hematopoietic chimerism after HCT,” the researchers wrote. “Combined with αCD117 antibody, transient T cell depletion, and just 10 centigray (cGy) total body irradiation (TBI), these agents enabled durable mixed chimerism and matching allo-islet tolerance, to cure diabetes without evidence of [graft-versus-host disease].”
This new combination allowed researchers to reduce radiation exposure to 10 cGy, a fraction of the levels used in conventional bone marrow transplantation. Mice treated using this regimen showed stable engraftment of donor cells, maintained fertility, and experienced no graft-versus-host disease. They also remained insulin-independent for the duration of the study.
The findings provide a potential pathway toward clinical adoption, which could be speedier than usual since many of the agents used for this approach are already approved or under evaluation in humans.
Work at Stanford will continue in this area and will focus on testing the reduced-intensity regimen in autoimmune diabetes models, refining conditioning strategies, and exploring alternative sources of islet cells, including those derived from stem cells.
If successfully, translated to the clinic, this treatment regimen could reduce or eliminate the need for lifelong insulin therapy, while expanding the use of transplantation-based therapies across a wider set of patients.
The post New Low-Toxicity Transplant Method Reverses Type 1 Diabetes in Mice appeared first on Inside Precision Medicine.


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