Exosomal miR-2467-3p derived from human umbilical cord mesenchymal stem cells promotes diabetic wound healing by regulating autophagy via targeting CYP1A1.

OBJECTIVE

This study aimed to investigate the molecular mechanisms by which human umbilical cord-derived mesenchymal stem cell exosomes (hUC-MSC-Exo) promote diabetic wound healing by focusing on the delivery of specific microRNAs (miRNAs) that regulate downstream target genes and subsequently activate the autophagy pathway.

METHODS

A skin defect model was established in mice with type 2 diabetes mellitus (DM) using a high-fat diet combined with streptozotocin injection. The therapeutic effect of locally administered hUC-MSC-Exo was evaluated. Wound healing quality, collagen deposition, autophagic activity, and oxidative stress levels were analyzed using histological staining (hematoxylin-eosin (HE) and Masson), immunofluorescence (IF), and Western blotting. Human immortalized keratinocytes (HaCaTs) were treated with high glucose (HG) to mimic a diabetic microenvironment. The effects of MSC-Exo on cell function, reactive oxygen species (ROS) levels, and autophagy were assessed. Bioinformatics screening, gene knockdown/overexpression, dual-luciferase reporter assay, and quantitative PCR were employed to identify and validate the key target gene, Cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1), and its upstream regulatory miRNA, miR-2467-3p.

RESULTS

Mice treated with hUC-MSC-Exo showed significantly accelerated wound closure, manifested by increased collagen deposition and enhanced autophagy activity. In vitro, MSC-Exo were internalized by HaCaT cells, which further promoted cell growth by activating autophagy. These effects were reversed by the autophagy inhibitor, 3-MA. CYP1A1 expression was significantly upregulated both in vivo and in vitro, whereas MSC-Exo treatment reduced its expression levels. Functionally, CYP1A1 knockdown mimicked the effects of MSC-Exo, whereas CYP1A1 overexpression produced opposite effects, antagonizing the benefits of MSC-Exo. The dual-luciferase reporter assay confirmed that miR-2467-3p directly binds to the 3'UTR of CYP1A1 and inhibits its expression. miR-2467-3p was enriched in MSC-Exo and delivered to recipient cells. Inhibition of miR-2467-3p markedly attenuated the ability of MSC-Exo to downregulate CYP1A1, subsequently reducing autophagy and suppressing cell growth.

CONCLUSION

This study demonstrates that hUC-MSC-Exo promotes diabetic wound healing by delivering miR-2467-3p, which further inhibits CYP1A1 expression and activates autophagy. Our findings revealed a novel MSC-Exo/miR-2467-3p/CYP1A1/Autophagy regulatory axis, providing a potential therapeutic target for wound healing in DM.