3D Bioprinting of Double‐Layer Conductive Skin for Wound Healing

Conductive hydrogels are highly attractive in 3D bioprinting of tissue engineered scaffolds for skin injury repair. However, their application is limited by mismatched electrical signal conduction mode and poor printability. Herein, the 3D bioprinting-assisted fabrication of a double-layer ionic conductive skin scaffold using a newly designed ionic conductive biomimetic bioink (GHCM) is reported, which is composed of gelatin methacrylate (GelMA), oxidized hyaluronic acid (OHA), carboxymethyl chitosan (CMCS), and 2-methacryloyloxyethyl phosphorylcholine (MPC) for the treatment of full-thickness skin defects. The combination of rigid (GelMA) and dynamic (OHA-CMCS) polymer networks imparts GHCM bioink excellent reversible thixotropy, enabling good printability, and allowing the creation of skin-like constructs with high shape fidelity and cell activity by convenient one-step bioprinting. Moreover, the incorporation of zwitterionic MPC endows the bioink with electrical signaling pattern similar to that of natural skin tissue. By integrating human foreskin fibroblasts (HFF-1), human umbilical vein endothelial cells (HUVECs), and human immortalized keratinocytes (HaCaTs), a double-layer conductive skin scaffold comprising an epidermal layer and a vascularized dermal layer is created. In vivo experiments have demonstrated that the conductive skin scaffolds provide an appropriate conductive microenvironment for cellular signaling, growth, migration, and differentiation, ultimately accelerating the re-epithelialization, collagen deposition, and vascularization of skin wounds, which may represent a general and versatile strategy for precise engineering of electroactive tissues for regenerative medicine applications.