Engineered stem cells show promise in reversing type 1 diabetes in mice by reprogramming immune response

Researchers at the Medical University of South Carolina have demonstrated that a single infusion of engineered mesenchymal stem cells can reverse new-onset type 1 diabetes in female mice by modulating immune cells, sparking hope for cell-based treatments aiming to restore immune tolerance.

Researchers at the Medical University of South Carolina have reported that a single infusion of engineered mesenchymal stem cells helped reverse new-onset type 1 diabetes in more than half of treated female mice, raising fresh interest in cell-based approaches that aim to reset autoimmunity rather than simply manage blood sugar. The work, published in Molecular Therapy, used mesenchymal stem/stromal cells modified to produce more alpha-1 antitrypsin, a protein known for anti-inflammatory effects, and found that the treatment was able to restore glucose control in a substantial proportion of animals.

The findings matter because current treatment for type 1 diabetes still depends mainly on insulin replacement, which can control glucose but does not stop the immune system from destroying pancreatic beta cells. According to the study, the engineered cells appeared to change that immune environment by strengthening regulatory T cells, or Tregs, which help restrain immune attacks, while pushing harmful CD8+ T cells into an exhausted state that makes them less able to kill beta cells. The treatment also reduced immune-cell infiltration in the pancreatic islets, the clusters of cells that contain the insulin-producing beta cells.

The researchers used female non-obese diabetic mice with recent-onset diabetes and gave them one intravenous dose of the engineered cells. By week five, about 61% of treated mice were diabetes-free, while none of the untreated animals entered remission. By week 10, roughly 54% of the remaining treated mice still had no diabetes after some animals had been removed for analysis. The study also found lower levels of inflammatory signalling in pancreatic lymph nodes, alongside fewer signs of insulitis, the immune invasion of the islets that drives type 1 diabetes.

Mechanistically, the team said the therapy did not simply increase the total number of Tregs, but enriched the subset thought to be most suppressive and effective. In functional testing, Tregs from treated mice were better at damping T-cell proliferation than those from untreated mice. The approach also reduced Th1 activity, another inflammatory immune pathway, and single-cell analysis suggested that many of the interferon-responsive CD4+ T cells seen in the pancreas-associated lymph nodes came from untreated animals rather than treated ones. The effect extended beyond mice: when human donor immune cells were cultured with the engineered stem cells, the proportion of Tregs increased.

The study also pointed to a second arm of the response, centred on CD8+ T cells, which are the main cells that directly destroy beta cells in type 1 diabetes. The engineered stem cells appeared to encourage these cells towards an exhausted, less destructive state, and Tregs educated by the treatment had the strongest effect on that process. The authors noted, however, that the work was limited to female mice and that further research is needed before the therapy could move towards clinical testing. They also said regulators would expect full chemistry, manufacturing, controls, potency and long-term safety data before any human trial could begin.