3D bioprintable Mg2+-incorporated hydrogels tailored for regeneration of volumetric muscle loss.

Abstract

Rationale: Current therapeutic approaches for volumetric muscle loss (VML) face challenges owing to limited graft availability and insufficient bioactivity. Three-dimensional (3D) bioprinting has become an alternative technology for fabricating native tissue-mimetic grafts, allowing for tailored structures and complex designs. Methods: We developed an Mg²⁺-incorporated bioink composed of thiolated gelatin (GtnSH) and maleimide-conjugated gelatin (GtnMI) decorated with magnesium peroxide (MgO₂), referred to as a GtnSH/GtnMI/MgO₂ bioink. We designed in situ crosslinking between GtnSH and GtnMI to prepare cytocompatible bioink for 3D bioprinting of muscle mimetics. Results: The incorporated MgO₂ particles provided oxygen supplementation and myogenic cues. In vitro assays demonstrated that C2C12 myoblasts encapsulated in the GtnSH/GtnMI/MgO₂ bioink exhibited high viability, intrinsic proliferation rate, and increased expression of key myogenic markers. In vivo transplantation of the 3D bioprinted GtnSH/GtnMI/MgO₂ constructs facilitated muscle mass restoration and M2 macrophage polarization. Additionally, they downregulate the activities of CD4⁺ and CD8⁺ lymphocytes, inducing a transition from the initial inflammatory to the restoration phase. Conclusion: The GtnSH/GtnMI/MgO₂ bioink is a potential therapeutic strategy for enhancing myogenesis and skeletal muscle tissue regeneration.