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ROS scavenging ability. Notably, the hydrogel could transform M1 into M2

macrophages without any additional components. Hypoxic bone marrow mesenchymal

stem cell-derived exosomes (hyBMSCExos) were important in regulating cellular
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functions through the microRNAs they carry. Kui Xu et al. showed a multifunctional
hydrogel based on gallic acid (GA)-coupled chitosan (CSGA) and partially oxidized

hyaluronic acid (OHA). Hybmscexos-loaded hydrogels showed excellent ability to

promote diabetic wound healing by modulating macrophage polarization to the M2. It

can be ascribed to that the extracellular vesicle miR-4645-5p and the antioxidant

properties of the hydrogel work together to inhibit the activity of SREBP2 in

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macrophages. Yongjun Zheng et al. designed a methacrylic acid GelMA hydrogel for
sustained release from the wound and evaluated its potential as a hydrogel for

promoting wound healing in diabetic patients. Mechanistic studies showed that the

wound liner regulated macrophage heterogeneity through the A2bR/STAT/PPARγ

signaling pathway and promoted endothelial cell function, thereby accelerating wound
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healing in diabetic patients. Xueqi Gan et al. developed and applied a silk

fibroin/gelatin (SG) gel for chronic diabetic wounds and incorporated Mdivi-1 (SG/M).
Compared with pure SG hydrogel, the SG/M hydrogel obviously improved wound

healing in diabetic patients. The therapeutic value of Mdivi-1 depended on enhancing

macrophage polarization to M2 and retaining mitochondrial dynamics and function

disorders mediated by high glucose in macrophages and human umbilical vein

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endothelial cells (HUVECs). Zhihong Su et al. prepared an asymmetric bilayer
hydrogel by ultraviolet polymerization of chemically modified CS (TA@CS)

chemically combined with deamidated and pyrogallol-derivative of marine collagen

(JDP). Simultaneously, asymmetric hydrogel exhibited asymmetric adhesion property,

a property critical for repairing diabetic and gastrointestinal wounds, which can avoid

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the complexity of gel application during surgery and the risk.
3.3. Promoting angiogenesis and tissue regeneration

In the process of diabetic wound healing, angiogenesis and tissue regeneration

were the key biological links that ultimately determine the repair effect. They

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