FIG. 2.

Schematic overview of various types of electroconductive scaffolds used in cardiac tissue regeneration. (A) Overview of the concept of using a suture-free technology for the attachment of an engineered cardiac patch to the organ. The process from left to the right of the panel can be explained as: Gold nanorod adsorption; cardiac cell seeding; cardiac tissue assembly; patch location and integration by NIR; and finally, the cardiac patch after integration to a rat heart.³⁶ (B) A schematic illustrating the fabrication steps to produce 3D biohybrid actuators composed of cardiac tissue on top of a multilayer hydrogel sheet impregnated with aligned CNT microelectrodes.⁴⁵ (C) Designing a multilayered hybrid scaffold, including nanofibers and hydrogels, that can suitably mimic the native cardiac tissue structure. The first step is to design an interwoven, aligned structure, and scaffold with a network structure from nanofibers of Yarn (NFYs-NET), which possess the benefits for native cardiac tissue. The middle row demonstrates the native myocardium showing a gradual transition of aligned cell layers from the endocardium to the epicardium and shows schematics of multiple layers of NFYs-NETs assembled with a gradual orientation transition. The bottom row shows the fabrication process of one-layer 3D NFYs-NET/GelMA hybrid scaffolds and subsequent CMs cultivation. A single-layer hybrid 3D scaffold is formed through encapsulating a single NFYs-NET layer within a GelMA hydrogel shell after photocrosslinking with UV-radiation. (D) Schematic concept of using a cell-laden hydrogel bioink originating from the patient's own cells that are reprogrammed to become pluripotent and then differentiated to CMs and endothelial cells and encapsulation within the hydrogel for 3D bioprinting functional cardiac tissue (so-called personalized tissue regeneration).⁴⁶ (E) Schematic concept of the application of an engineered functional and injectable cardiac patch through a shape/memory scaffold. The scaffolds recover their initial shape following injection. An image of the minimally invasive implanted injectable cardiac patch on the porcine heart without open-heart surgery is also shown.⁴⁷ 3D, three-dimensional; CMs, cardiomyocytes; CNT, carbon nanotube; GelMA, gelatin methacryloyl; NIR, near infrared; UV, ultraviolet.