Bioengineered Electrically Conductive and Tri-cellularized Hydrogel as a Synthetic Muscle Graft for Volumetric Muscle Loss Patients

Introduction: Volumetric Muscle Loss (VML) is an acute traumatic muscle injury resulting in 20% or more significant loss of the native muscle tissue and affects many military personnel and civilians. VML leads to substantial loss of muscle matrix, vasculature, and neural components needed for electric-motor control, leading to long-term disability. Therefore, VML injuries go beyond the normal regenerative capacity of skeletal muscle and require extensive therapy. Despite recent advances in cell transplantation and biomaterials, there are currently no treatments for VML that completely recover the lost muscle tissue and function. Purpose: An electrically conductive polymer integrated into Gel-MA Alginate will increase conductivity levels within the hydrogel, allowing for cell-to-cell signaling in Tri-cellularized tissue constructs leading to faster regeneration and full functioning restoration. Methods: The 3D printing ink for conductive scaffolds was prepared by mixing specific concentrations of gelatin methacrylate, sodium alginate, and Poly 3,4-Ethylenedioxythiophene-Poly Styrene Sulfonate (PEDOT: PSS) in Dulbecco’s phosphate buffered saline. Hydrogels were tested for viscoelastic properties measurements, 3D printing parameter optimization, mechanical properties, electrical conductivity, and swelling testing. In-vitro and in-vivo testing using electrically conductive and cellularized (Tri-culture system- muscle+ neurons+ endothelial cells) 3D-printed muscle grafts loaded with PGE 2 is conducted to evaluate proliferation, differentiation, and molecular mechanisms leading to muscle regeneration. Results: Viscoelastic measurements indicated no significant changes in the complex viscosity of the three tested hydrogels. The addition of sodium alginate into the GELMA and GELMA-PEDOT:PSS increased the mechanical properties of the scaffolds. The polymer hydrogel has shown dramatic increases in electrical flow and current pathways compared to pure GelMA hydrogels. The results indicated increased absorption in alginate. Raman results confirmed the incorporation of sodium alginate and the PEDOT: PSS into the GELMA hydrogel structure, which enhanced the mechanical properties of the construct. The 3D printed scaffolds enhanced the skeletal muscles, neuronal, and endothelial cells attachment and viability. Our in-vitro studies have shown that PGE 2 significantly enhances neurite outgrowth for NMJ formation and accelerates muscle cell differentiation and regeneration after damage while also promoting myoblast and neuronal cell proliferation and differentiation. The synthetic muscle grafts are being tested in-vivo, and we expect enhanced muscle regeneration and functional restoration. Conclusion: These bioengineered electrically conductive muscle grafts show promising properties for enhanced muscle regeneration after VML. These studies received support from the UT-System TRC4 and UTSW-NCATs grant # 1UL1TR003163-04 grants. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.