A spatiotemporal release hydrogel based on an M1-to-M2 immunoenvironment for wound management.

Cutaneous wounds remain a major clinical challenge that urgently requires the development of advanced and functional wound dressings. During the wound healing process, macrophages are well known to exhibit temporal dynamics with a pro-inflammatory phenotype at early stages and a pro-healing phenotype at late stages, thus playing an important role in regulating inflammatory responses and tissue regeneration. Meanwhile, disrupted temporal dynamics of macrophages caused by poor wound local conditions and deficiency of macrophage function always impair the wound-healing progression. Here in this work, we proposed a novel controllable strategy to construct a spatiotemporal dynamical immune-microenvironment for the treatment of cutaneous wounds. To achieve this goal, a concentric decellularized dermal hydrogel was constructed with the combination of type 1 and type 2 macrophage-associated cytokine complexes in the sheath portion and core portion, respectively. The in vitro degradation experiment exhibited a sequential cascade release of pro-inflammatory cytokines and pro-healing cytokines. The enhanced cell biocompatibility and tube formation of HUVECs were confirmed. A full-thickness skin defect model of rats was developed to analyze the effect of the spatiotemporal dynamical bioactive hydrogels on wound healing. Remarkable angiogenesis, rapid wound restoration, moderate extracellular matrix deposition and obvious skin appendage neogenesis were identified at different time points after treatment with the macrophage cytokine-based decellularized hydrogels. Consequently, the concentric decellularized hydrogels with spatiotemporal dynamics of immune cytokines have considerable potential for cell-free therapy for wound healing.