Melt-Based Embedded Printing of Macroscopically-Conformal, Electro-Conductive and Elastomeric Patches for Improved Myocardial Infarction Repair

Poly(glycerol sebacate) (PGS) is promising for engineering flexible cardiac patches for myocardial infarction repair due to its unique elasticity. However, its insulating nature and complex thermal curing process hinder existing 3D printing techniques from producing patches that recapitulate the mechanical, electrical, and anatomical features of native myocardium. Here, a melt-based embedded printing strategy enabling direct, freeform fabrication of thermosetting PGS architectures with in situ thermal curing is proposed. The viscoelastic matrix enables high-fidelity extrusion of PGS prepolymer into microscale filaments while providing temporary support for in situ curing of PGS elastomeric architectures with seamless interface fusion and mechanical stability. This platform further allows direct printing of electro-conductive cardiac patches using carbon nanotube-incorporated PGS that mimic ventricular curvature and mechanical anisotropy. Compared to pure PGS controls, the electro-conductive patches enhance cardiomyocyte maturation in vitro, evidenced by improved sarcomere organization, calcium handling, and electrical synchronization. In vivo, these acellular patches improve mechanical integration with host myocardium, promote vascularization, reduce inflammation, and preserve cardiomyocyte survival, collectively maintaining ejection fraction and attenuating adverse remodeling. This work, therefore, establishes a generalizable manufacturing strategy for printing thermosetting elastomeric constructs with integrated conductivity as acellular, mechanically and electrically functional patches for structural cardiac repair.