Immunometabolic reprogramming of macrophages by miR-423-5p-enriched small extracellular vesicles delivered via...

Chronic diabetic wounds remain a formidable clinical challenge due to a self-sustaining immunometabolic dysfunction. The hyperglycemic and pro-oxidative microenvironment locks infiltrating macrophages in a glycolysis-dependent pro-inflammatory state, actively suppressing the phenotypic switch to pro-reparative M2 polarization and severely impairing angiogenesis. Current single-target interventions fail to disrupt this vicious inflammatory-metabolic cycle, underscoring an urgent need for strategies capable of spatiotemporally resetting local immune homeostasis.

In this study, the pro-reparative capacity of ADSCs-EVs and UCMSCs-EVs was systematically compared through a panel of in vitro functional assays (proliferation, migration, tube formation, and macrophage polarization) and a diabetic mouse wound model. Small RNA sequencing was employed to identify a key effector miRNA enriched in UCMSCs-EVs, and its target regulatory mechanism was validated through miRNA mimic transfection combined with HDDC3 overexpression rescue experiments. Meanwhile, a glucose/ROS dual-responsive injectable hydrogel (DCH) was constructed from oxidized dextran, carboxymethyl chitosan, and phenylboronic acid-modified hyaluronic acid via physical mixing and dynamic double crosslinking through Schiff-base and boronate ester bonds, enabling the pathology-triggered, on-demand release of EVs.

Comparative bioactivity profiling revealed that extracellular vesicles derived from umbilical cord mesenchymal stem cells (UCMSCs-EVs) exhibited greater capacity than adipose-derived EVs to drive macrophage M2 polarization and metabolic reprogramming. Mechanistic dissection identified miR-423-5p as a highly enriched cargo within UCMSCs-EVs. This microRNA directly targeted and suppressed HDDC3 expression, thereby modulating the AMPK/mTOR signaling axis to enforce a metabolic shift from glycolysis toward fatty acid oxidation and establish a stable pro-repair phenotype. To address the poor retention and rapid clearance of free EVs within the hostile wound bed, an injectable dual-network hydrogel was engineered, integrating dynamic boronate ester and Schiff-base crosslinks. This smart platform maintained structural integrity under physiological conditions yet underwent selective dissociation exclusively in response to the elevated glucose and reactive oxygen species (ROS) levels characteristic of diabetic wounds. This pathology-triggered degradation facilitated on-demand, sustained release of UCMSCs-EVs while concurrently scavenging local ROS. The synergistic coupling of this microenvironment-responsive delivery with miR-423-5p-encoded immunometabolic regulation effectively resolved chronic inflammation and accelerated granulation tissue formation.

This study establishes a translatable framework for precision regenerative medicine by integrating stimuli-responsive biomaterial engineering with the intrinsic regulatory circuitry of stem cell-derived EVs, effectively overcoming the immunometabolic barriers inherent to diabetic tissue repair.