Curcumin pretreatment enhances the capacity of BMSC exosomes to attenuate renal ischemia-reperfusion injury by ferroptosis suppression via miR-16-5p/Smad3/Mb axis.

BACKGROUND: Renal ischemia-reperfusion injury (RIRI) refers to kidney damage following blood flow restoration, with limited effective treatments available. Bone mesenchymal stem cell (BMSC) derived exosomes exhibit therapeutic potential via targeted molecular delivery, though limited by isolation challenges and transient retention, while curcumin demonstrates multi-organ protective capacities in RIRI. METHODS: In vivo, RIRI mice received tail vein injections of BMSC exosomes (exo) or curcumin preconditioned BMSC exosomes (cur-exo). Biodistribution was tracked via bioluminescence/immunofluorescence, while therapeutic efficacy was evaluated through renal function parameters, histopathology, and ferroptosis biomarkers. In vitro, ferroptosis-induced renal tubular epithelial cells were treated with exo and cur-exo, with subsequent quantification of Fe²⁺, lipid peroxidation, glutathione, mitochondrial ultrastructure, ROS levels, and ferroptosis-related protein/mRNA expression. Mechanistic studies integrated transcriptomics, siRNA/overexpression systems, ChIP, dual-luciferase assays, SPR, Co-IP and bioinformatics to delineate anti-ferroptosis pathways of cur-exo and the effect of curcumin on miR-16-5p. RESULTS: Curcumin preconditioning can enhance the targeted delivery capability of BMSC exosomes to injured kidneys and improves the restoration of renal function and tissue damage in mice with ischemia-reperfusion injury by inhibiting ferroptosis. In vitro, TCMK-1 cells can take up both exo and cur-exo, with cur-exo significantly enhancing the survival rate of TCMK-1 cells induced by ferroptosis compared to exo. This is achieved by downregulating lipid peroxidation levels, improving iron overload and ROS accumulation, and restoring mitochondrial structure to exert anti-ferroptosis effects. Mechanistically, curcumin increases the expression of miR-16-5p in cur-exo by regulating the activity of CYP1B1, and cur-exo inhibits the translation of Smad3 by delivering miR-16-5p that targets the 3'UTR of Smad3, leading to the downregulation of myoglobin (Mb) transcriptional activity and thereby antagonizing ferroptosis in TCMK-1 cells. CONCLUSION: Our research indicates that curcumin preconditioned BMSC exosomes can exert a therapeutic effect on RIRI by inhibiting cellular ferroptosis. The primary mechanism behind this effect involves curcumin increasing the expression of miR-16-5p by modulating CYP1B1 activity, and cur-exo promoting the alleviation of ferroptosis in TCMK-1 cells through the miR-16-5p/Smad3/Mb axis. This study provides a new strategy for enhancing the biological functions of exosomes and presents new targets and ideas for the treatment of RIRI.