An Alginate/Gelatin Injectable Hydrogel Containing Au Nanoparticles for Transplantation of Embryonic Mouse Cardiomyocytes in Myocardial Repair

In advancing cardiac tissue engineering (CTE), the development of injectable hydrogels mirroring myocardial properties is pivotal. The designed hydrogels must not only support cardiac cell growth but also have to be conductive to properly promote the functionalities of cardiac cells. Here, a facile approach is developed to incorporate gold nanoparticles (AuNPs) into an injectable hydrogel composed of Alginate (Alg) and Gelatin (Gel). The resultant nanocomposite hydrogel boasts a porous interconnected network and superior conductivity (2.04 × 10-4 S cm^-1) compared to the base Alg/Gel hydrogel. Hydrogel hydration and in vitro degradation profiles affirm their suitability as carriers for cardiac cells. Importantly, Alg/Gel+AuNPs hydrogels exhibit no toxicity to mouse Embryonic Cardiac Cells (mECCs) over 7 days, elevating connexin 43 (Cx43) and cardiac troponin T (CTnT) gene expression compared to controls. Then, the Alg/Gel+AuNPs hydrogel is used as a carrier for intramyocardial delivery of mECCs in rats with myocardial infarction. The significant increase in α-Smooth Muscle Actin (α-SMA) and cardiac troponin T (CTnT) expression along with the increase in ejection fraction (EF), smaller infarction size, less fibrosis area confirmed that the hydrogel efficiently promoted the transmission of mechanical and electrical signals between transplanted cells and surrounding tissue.