Interaction of cardiomyocytes from CCND2-overexpressing human induced pluripotent stem cells with electrically conductive hydrogels

The use of biomaterials has been widely studied as a platform to deliver regenerative cells, such as human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs), into damaged heart tissue. However, these biomaterials often lack the electroconductivity needed for effective heart function. In this study, we developed a gold nanorod-embedded gelatin-methacrylate (GelMA-GNR) hydrogel scaffold seeded with hiPSC-CMs and hiPSC-derived cardiac fibroblasts (hiPSC-CFs). Three experimental groups, pristine GelMA (GelMA), GelMA embedded with 0.5 mg mL^-1 of GNRs (GelMA+0.5GNR), and GelMA embedded with 1.0 mg mL^-1 of GNRs (GelMA+1.0GNR), were included in this study. hiPSC-CMs at 28 days after initiation of cardiogenic differentiation were used. The hiPSC-CMs (2.4 million) and hiPSC-CFs (0.4 million) were co-cultured on the GelMA hydrogel scaffold for 14 days before experiments to evaluate cell maturation. Morphological assessments through immunofluorescence staining showed enhanced alignment, sarcomere structure, and connexin-43 expression in the two GNR-treatment groups. GNRs did not affect cell viability or spontaneous beating but promoted the expression of maturation markers and improved action potential propagation modestly, as evaluated by reverse transcript PCR and optical mapping. In conclusion, these findings demonstrate that GNR-enhanced scaffolds facilitate hiPSC-CM maturation, offering a promising approach to improve the maturation of engineered heart tissue.