An off-the-shelf bioactive EV delivering cryogel orchestrating immunomodulatory reprogramming and angiogenesis for diabetic ulcer healing.

Abstract

Chronic diabetic foot ulcers (DFUs) are marked by persistent inflammation, oxidative stress and hypoxia, leading to impaired healing and limited treatment success. While extracellular vesicles (EVs) are promising in modulating the immune microenvironment and promoting regeneration, their clinical use is constrained by instability and loss of function over storage. Alternatively, scaffolds that deliver oxygen have shown regenerative potential and can act as a delivery system for EVs. Here, we report a multifunctional Bioactive Oxygenated Off-the-Shelf EV Therapy (BOOST) that integrates lyophilized EVs, oxygen release and immunomodulatory function within a single cryogel scaffold. BOOST synergistically orchestrates immunomodulatory reprogramming, driving macrophages from a pro-inflammatory M1 to a pro-regenerative M2 phenotype while concurrently driving angiogenesis and collagen remodelling. As an off-the-shelf therapy, BOOST preserved EV bioactivity for over 6 months, delivered sustained oxygen and reduced ROS with accelerated wound closure in diabetic wounds. BOOST reprogrammed macrophage polarization and upregulated anti-inflammatory IL10 levels, directing angiogenesis (VEGF, CD31), collagen synthesis (COL1A and COLIIIA) and promoting hair follicle regeneration while mitigating oxidative stress (8-OHdG). This work presents a clinically relevant strategy that merges EV therapy with oxygen delivery and immune modulation to address multiple pathophysiological barriers, offering a potent off-the-shelf therapeutic solution for DFUs.