Dual-layer hydrogels composed of rhein and endothelial cell exosomes with differential degradation for inflammatory wound treatment

In this study, a dual-layer hydrogel (Exos HA-RC) for inflammatory wound treatment was designed. It consists of a rhein-chitosan (RC) lower layer and a hyaluronic acid methacrylate (HAMA) upper layer with HUVEC-derived exosomes (Exos HA). Using the differential degradation rates of the two layers, it precisely regulates wound healing. The RC layer releases rhein for anti-inflammation in the early stage, and the Exos HA layer releases HUVECs-exosomes (HUVECs-Exos) for angiogenesis in the later stages. In a mouse model, the Exos HA-RC significantly enhanced wound healing, showing potential for inflammatory wound treatment. • Dual-Layer Hydrogel: A novel dual-layer hydrogel (Exos HA-RC) was developed to address the unique challenges of inflammatory wound healing. • Stage-Specific Therapeutic Approach: The lower RC layer inhibits inflammation and oxidative stress in the early inflammatory phase, while the upper Exos HA layer promotes angiogenesis in the later phases. • Mechanistic Insights: Exos HA-RC exerts anti-inflammatory effects by inhibiting signaling pathways such as TLR4/NFκB and JAK2/STAT3, reducing the overexpression of inflammatory factors. • Endothelial Cell Exosome Incorporation: The Exos HA layer with HUVECs-derived exosomes is crucial for promoting angiogenesis in wound regeneration. • Innovative Wound Strategy: Exos HA-RC combines the antioxidative and anti-inflammatory properties of rhein with the regenerative power of exosomes, offering an novel approach to inflammatory wound healing. Inflammatory wounds pose significant clinical challenges, and conventional treatment methods often fail to adequately address the issues associated with them. Therefore, we developed a novel dual-layer hydrogel system with differential degradation for stage-specific inflammatory wound healing. The lower layer of the hydrogel is composed of rhein and chitosan (RC), while the upper layer consists of hyaluronic acid methacrylate (HAMA) loaded with exosomes (HUVECs-Exos) derived from human umbilical vein endothelial cells (Exos HA), forming the dual-layer hydrogel (Exos HA-RC). The Exos HA-RC exhibits significant differential degradation between its dual-layers. In vivo experiments revealed that the lower RC layer rapidly degrades during the inflammatory phase, effectively inhibiting inflammatory mediators and reducing oxidative stress. As the wound enters the proliferative and remodeling phases, the upper Exos HA layer, which degrades slowly, dominates to release HUVECs-Exos, promoting angiogenesis for inflammatory wound healing. Mechanistically, Exos HA-RC exerts its anti-inflammatory effects by inhibiting the activation of the TLR4/NFκB and JAK2/STAT3 signaling pathways. Overall, the dual-layer hydrogel system based on differential degradation offers a precise and multifunctional approach to inflammatory wound healing.