Figure 2.

Recent advances in the structure and function of bioprinted cardiac tissues. Bioprinting has enabled the fabrication of biomimetic cardiac features, including (A) SWIFT-printed perfusable branching vascular channels within a cardiac tissue matrix consisting of compacted OBBs, ECM, and fibroblasts, as well as structures printed via FRESH, including (B) a perfusable, multiscale, interconnected vascular network, printed from collagen type I (scale bar: 5 mm); (C) a neonatal-scale human heart with internal features such as trabeculae, printed from collagen type I; and (D) an adult-scale human heart printed out of alginate that possesses features like valves and ventricles. Reprinted (adapted) with permission from²⁶ (Copyright 2023 American Chemical Society). Bioprinted cardiac tissues also demonstrate improvements in function: (E) a SWIFT cardiac tissue demonstrated contractility with sensitivity to electrical stimuli (scale bar = 500 µm); (F) a simplified model of the left ventricle FRESH-printed using collagen type I demonstrated circumferential calcium wavefront propagation (scale bar: 1 mm); (G) hiPSC-derived cardiomyocytes and fibroblasts cast in a collagen gel around a FRESH-printed collagen linear heart tube induced unidirectional fluorescent bead displacement, indicating pumping capabilities (scale bar: 1 mm); and (H) a FRESH-printed hChaMP demonstrated pumping and thus pressure generation, quantified as pressure-volume loops (scale bar = 0.5 cm). This figure is adapted with permission from references.^4,5,26,32,33