Abstract 18051: Engineering of Functional Cardiac Tissue Patch with Realistic Myofiber Orientations
To maximize the potential to repair cardiac damage without causing arrhythmias, tissue engineered cardiac patches should not only contain dense, well-coupled and differentiated cardiomyocytes, but also recapitulate the spatially varying muscle fiber directions in the native tissue. To this end, we previously developed a mesoscopic hydrogel molding method to reproducibly engineer porous cardiac tissue constructs with controlled 3D cell alignment. Using this method, we now report engineering relatively large (25 × 25 mm2) and thick (219 ± 18 μm) cardiac tissue patches with realistic epicardial fiber orientations derived from diffusion tensor MRI (DTMRI) maps of human ventricle (Fig. A). Specifically, a mixture of neonatal rat cardiomyocytes and fibrin gel was casted within elastomeric tissue molds containing sub-mm sized posts oriented along the DTMRI vectors. Densely packed cardiomyocytes oriented along the post directions (Fig. B) and robustly expressed connexin-43 and N-cadherin at cell boundaries (Fig. C). Membrane staining of cardiomyocytes in 4-week-old constructs revealed registered sarcolemmal invaginations, indicating the maturation of T-tubules (Fig. D). To elucidate the effects of locally altered myofiber directions on electrical conduction, we optically mapped (60 μm spatial resolution) the propagation of Ca2+ transients in 7x7 mm2 constructs with the most abrupt change in fiber direction of 90° (Fig. E1&2). The propagation in longitudinal vs. transverse fiber direction in this setting caused rate-dependent changes in conduction velocity of 23.4 ± 2.2 vs. 17.1 ± 1.9 cm/s at 2Hz, and 17.6 ± 1.4 vs. 10.6 ± 1.1 cm/s at 5Hz pacing rate. At higher pacing rates (6 ± 0.5Hz), conduction block preferentially occurred in the transverse direction, without inducing sustained reentry. In conclusion, our approach enables reproducible fabrication of a highly functional, anisotropic tissue patch with realistic cardiac fiber directions.
- © 2010 by American Heart Association, Inc.