Potential Roles of Silicon/Silica‐Based Nanoparticles in 3D Printed Hydrogels for Skeletal Muscle Regeneration

Abstract

Introduction : Skeletal muscle constitutes about 40% of the total body mass and plays a significant role in the movement of the human body. Although skeletal muscles have remarkable endogenous regenerative capacity, this capacity is overwhelmed following acute severe traumatic injuries. Furthermore, the associated oxidative damage can delay regeneration process and prolong recovery. These traumatic injuries result from combat- and/or trauma-induced muscle injuries and often lead to irreversible tissue damage and impaired vascularization. Volumetric muscle loss (VML) is a severe traumatic injury that results in a critical loss (≥ 20%) of the native muscle mass leading to permanent disability. Our hypothesis is that using 3D bioprinted hydrogel modified with silica-based nanoparticles (NPs) laden human skeletal muscle cells will provide the required architecture and enhance muscle regeneration in VML defects where high levels of reactive oxygen species (ROS) is predominant. Materials and Methods Sodium metasilicate powder was used to adjust and optimize the effective concentration of ionic silicon, while hydrogen peroxide was used as sources of ROS to simulate the oxidative damage conditions of VML injuries. Silica based nanoparticles were embedded into GelMA-based hydrogels for 3D printing of scaffolds that mimic the skeletal muscle architecture. Results Our preliminary data using ionic silicon indicated that Si-ions are not cytotoxic to myoblast cells under tested concentrations (0.1-2.0 mM) (Figure 1). Furthermore, Si-ions significantly enhanced myoblast cell viability, proliferation, and differentiation into myotubes as indicated by a higher fusion index compared to the control. In-vitro studies indicated that0.4 mM of H2O2 into the growth media significantly decreases the cell viability after 6 and 24 hr. compared to the control (**p < 0.01, n=4 per group). Addition of 0.5-1.0 mM of Si into the growth media significantly enhances the cell viability under conditions that mimic high ROS (i.e., H202 treated group). The 3D printed scaffolds of GelMA + NPs indicated a higher myoblast cell viability significantly reducing cell death compared to the bare GelMA scaffolds as shown at Figure 2. Conclusion Our preliminary findings conclude that 0.1 mM Si-ions enhance myoblast viability, proliferation, and differentiation of C2C12 myoblast cells. Using 0.4 mM of H2O2 can simulate the oxidative damage condition in myoblast cells in-vitro. Using 0.1-0.5 mM silicon ions can attenuate the oxidative damage (0.4 mM H2O2) on C2C12 myoblast cells. 3D printed hydrogels loaded with silica-based nanoparticles are promising materials for 3D printing of muscle constructs.