Introduction: Islet graft dysfunction is mainly driven by hypoxia-induced injury. ROS generated under hypoxic conditions oxidize membrane thiol (–SH) groups into disulfides (S–S), disrupting redox homeostasis and aggravating islet damage. However, ROS-targeted therapies have shown limited efficacy, highlighting the need for alternative strategies. In this study, we developed fusogenic liposomes (DA-1) that anchor to the cell membrane and competitively scavenge hypoxia-induced ROS. This preserves surface –SH groups, restores redox balance, and alleviates oxidative injury, ultimately improving islet cell survival and function. Mechanistically, this redox stabilization enhances mitochondrial energy metabolism, supporting β-cell viability and insulin secretion, and improving transplantation outcomes.
Method: Islet cell activity was assessed by flow cytometry, redox status by DCFH-DA fluorescence, and insulin secretion following glucose stimulation by ELISA. Transmission Electron Microscope(TEM) was performed to examine ultrastructural features of the islet. Neonatal porcine islets were transplanted under the renal capsule of NCG mice. Fourteen days post-transplantation, grafts were retrieved for transcriptomic analysis. Graft function was evaluated by insulin immunohistochemistry, viability by TUNEL staining, and redox homeostasis by thiol-specific labeling.
Results: In vitro, DA-1 efficiently bound islet membranes (>95% at 15 min, 10 μg/mL) and was retained >90% for 7 days. Under hypoxia conditions, islet cells exhibited disrupted redox homeostasis, evidenced by reduced membrane thiol (–SH) levels due to excessive ROS accumulation. DA-1 treatment significantly restored membrane thiol expression (45.60 ± 5.51% vs. 59.87 ± 2.53%) and lowered intracellular ROS levels (mean fluorescence intensity: 132.90 ± 3.70 vs. 87.50 ± 6.75), thereby improving islet cell viability (29.33 ± 2.98% vs. 46.20 ± 9.00%) and glucose-stimulated insulin secretion (5.15 ± 2.26 vs. 22.58 ± 6.20 mIU/L). In vivo, DA-1–treated grafts maintained surface thiol expression, preserved insulin function, and reduced TUNEL+ apoptosis at days 3, 7, and 14 post-transplantation, in contrast to progressive functional decline in controls. Correlation analysis revealed that higher membrane thiol levels positively associated with better graft viability and insulin function. Transcriptomic analysis revealed enrichment in redox and mitochondrial metabolic pathways, confirmed by GO/KEGG. TEM further demonstrated DA-1–mediated preservation of mitochondrial ultrastructure under hypoxia, supporting its role in maintaining redox balance and mitochondrial energy metabolism to enhance graft function.
Conclusion: This study highlights redox regulation as a key determinant of islet graft outcome under hypoxia stress. By stabilizing the SH/S–S redox interface and protecting mitochondrial function, DA-1 offers a promising strategy to enhance islet viability and therapeutic efficacy in transplantation.