Fully Reduced HMGB1-Containing Peptide-Based Polyurethane Scaffold with Minimal Functional Unit of Skin (MFUS) Enhances Large and Deep Wounded Skin Healing

A novel peptide-based polymer is developed by lysine-diisocyanate (LDI), glycerol (Gly), and fully reduced HMGB1 (frHMGB1). This frHMGB1-LDI-Gly polymer either forms sponge-like foam (scaffold) or a hydrogel or a film under different reaction conditions. It degrades into nontoxic lysine, glycerol, and frHMGB1. The hydrogel glues tissues together and the glued tissues have strong mechanical properties. The film and scaffold provide the suitable environment for enhancing cell proliferation by releasing frHMGB1. The scaffold carries 1 mm diameter of full-thickness rat skin-island as a minimal functional unit of skin (MFUS) to treat large full thickness skin wounds, and the hydrogel glues the MFUS and scaffold with skin edges together (MFUS+Scaffold group). The scaffold treated wounds (Scaffold group) heal much faster than the wounds either treated with MFUS (MFUS group) or without treatment (Wound group). The MFUS+Scaffold treated wound regenerates more functional full-thickness skin with more hair follicles and sweat glands, higher CD146 and α-smooth muscle actin levels, more blood vessels and collagen productions, and less scar tissues when compared to the other three groups. The results demonstrate that the combination of frHMGB1-LDI-Gly polymer with MFUS provides a new tissue engineering approach for large full-thickness skin wound healing.