Protective Effects of PD-L1-Overexpressing MSCs and Their Derived Extracellular Vesicles in Type 1 Diabetes.

This study was conducted to address the urgent need for novel therapies for type 1 diabetes. We investigated whether programmed death-ligand 1 (PD-L1)-overexpressing mesenchymal stromal/stem cells (PD-L1-MSCs) and their extracellular vesicles (PEVs) can modulate immune responses and protect pancreatic islets, and whether these effects depend on PD-L1 signaling. Our results demonstrate that both PD-L1-MSCs and PEVs suppress T-cell activity, enhance regulatory T-cell populations, delay the onset of diabetes, and reduce immune cell infiltration in pancreatic islets. These findings suggest that PD-L1-MSCs and PEVs represent promising therapeutic strategies for type 1 diabetes by promoting immune tolerance and preserving β-cell function.