Programming Cellular Alignment in Engineered Cardiac Tissue via Bioprinting Anisotropic Organ Building Blocks

Abstract

To date, several methods have been developed to induce alignment in engineered cardiac tissues. [7][8][9][10][11] One common approach is to seed cardiomyocytes onto micro-or nanopatterned surfaces that contain topographical cues, which guide cellular alignment. [12,13] Another approach is to seed cells onto anisotropic polymer scaffolds [14][15][16] or decellularized matrices [17] that guide tissue alignment. In addition, cell-laden hydrogels seeded into molds of varying geometry can self-assemble into aligned cardiac rods, rings, bundles, and sheets. [18][19][20][21][22][23][24] Unfortunately, these methods are typically confined to thin cardiac tissues (≤100 µm thick) with either linear or radial alignment. By contrast, extrusionbased bioprinting offers broad flexibility to control tissue composition and architecture. Recently, we and others have demonstrated that synthetic and biological fibers exhibit shear-induced alignment during printing, opening the possibility to program tissue alignment via cell templating. [25][26][27][28][29][30][31][32][33][34] However, programming the architecture of human tissues by directly aligning anisotropic tissue building blocks has yet to be explored.Here, we report the fabrication of engineered cardiac tissue with programmable alignment via bioprinting of anisotropic organ building blocks (aOBBs) (Figure 1). These aOBBs are elongated microtissues composed of cellular aligned hiPSC-CMs that can be modularly assembled into a printable bioink (Figure 1a). Individual aOBBs within this bioink align along the print path due to the same shear and extensional forces that orient acellular fibers upon extrusion through a tapered nozzle (Figure 1b). [35] Using this method, we fabricated cardiac tissues with high cellular density and programmed alignment across multiple length scales; ranging from individual aOBBs to the sarcomeric machinery that drives their contractile function (Figure 1c). Results and DiscussionThe first step in creating our cardiac bioink is to fabricate scalable micropillar arrays by stereolithography (SLA). These micropillar arrays are used to generate tens of thousands of aOBBs with controlled aspect ratio and cellular composition. After optimizing these parameters, we employed a sequential transfer micromolding process to create a single contiguousThe ability to replicate the 3D myocardial architecture found in human hearts is a grand challenge. Here, the fabrication of aligned cardiac tissues via bioprinting anisotropic organ building blocks (aOBBs) composed of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) is reported. A bioink composed of contractile cardiac aOBBs is first generated and aligned cardiac tissue sheets with linear, spiral, and chevron features are printed. Next, aligned cardiac macrofilaments are printed, whose contractile force and conduction velocity increase over time and exceed the performance of spheroid-based cardiac tissues. Finally, the ability to spatially control the magnitude and direction of contractile force...

Emerging technologies for cardiac tissue engineering and artificial hearts

“…Ahrens et al described a bioprinting strategy to achieve aligned cardiac tissues by using a gelatin-fibrinogen ECM bioink containing anisotropic organ building blocks as shown in Figure 1A. 45 These building blocks were composed of human iPSC-derived cardiomyocytes, which could assemble along the printing path under the action of shear and extensional forces (Figure 1B). Based on the facile bioprinting model, the cardiac constructs based on living units with different architectures, including linear, spiral, and chevron patterns, could be obtained (Figure 1C).…”

“…Ahrens et al. described a bioprinting strategy to achieve aligned cardiac tissues by using a gelatin‐fibrinogen ECM bioink containing anisotropic organ building blocks as shown in Figure 1A 45 . These building blocks were composed of human iPSC‐derived cardiomyocytes, which could assemble along the printing path under the action of shear and extensional forces (Figure 1B).…”

“…(C) Bioprinting‐derived cardiac constructs composed of various featured architectures: (i) linear, (ii) chevron, and (iii) spiral ones. Source : (A–C) Reproduced with permission 45 . Copyright 2022, John Wiley and Sons.…”

Leaf-venation-directed cellular alignment for macroscale cardiac constructs with tissue-like functionalities

“…To generate functional cardiac and vascular tissues, the critical point is to recapitulate the physiologically relevant, highly aligned and densely packed cellular arrangement, eliciting the tight intercellular connections which govern their concerted biological activity (1,30). To achieve this, we propose an LVD strategy using leaf venation microchannels as geometric con nement to guide the morphological evolution of high-density cells in ECM hydrogel.…”

Tailored Polypeptide Star Copolymers for 3D Printing of Bacterial Composites Via Direct Ink Writing

“…[3] Various maturation. [20,21] It should be noted that the behavior of cellular components within the 3D environment may be regulated by the physical and chemical properties of the hydrogel network allowing for further tuning of performance. [22] This is of particular interest for the 3D printing of bacterial composites [23][24][25] where the controlled fabrication of these living systems holds significant potential in wound-healing, [26] bioremediation, [27] and biosensor applications.…”