Abstract 17173: Impact of Geometry and Cell Density on Structural and Functional Maturation in Large-format Mesh Engineered Cardiac Tissues Generated From Human iPS Cells

• Published in: Circulation (New York, N.Y.) N.Y.), 2016-11, Vol.134 (Suppl_1 Suppl 1), p.A17173-A17173
• Main Authors: Nakane, Takeichiro, Maumoto, Hidetoshi, Tinney, Joseph P, Yuan, Fangping, Kowalski, William J, Ye, Fei, Minakata, Kenji, Ikeda, Tadashi, Sakata, Ryuzo, Yamashita, Jun K, Keller, Bradley B
• Format: Article
• Language: English
• ISSN: 0009-7322; 1524-4539

BackgroundLinear-shaped engineered cardiac tissues (ECTs) from human iPSC-derived cardiovascular cells demonstrate therapeutic and myocardial regenerative potential in rat MI models; however, this format is not scalable for clinical use. Therefore, we developed a scalable, porous large-format ECT.Methods & ResultsWe explored multiple 15x15 mm ECT geometries using PDMS molds with rectangular internal short posts at a staggered position (mesh, ME) and molds without posts (plain sheet, PS) or with long parallel posts (multiple linear bundles, ML). We combined hiPSC-derived cardiomyocytes and vascular cells with a gel matrix (6M cells/construct, 15M cells/ml density), then poured the mixture into tissue molds to generate ECTs, which matured in vitro for 14 days. ME-ECTs displayed the lowest dead cell ratio (ME vs. ML vs. PS3.4±2.1 vs. 12.7±10.1 vs. 32.9±17.9%, p < 0.001). ME and ML-ECTs matured into 0.5 mm wide myofiber bundles with higher active stress (ME vs. ML vs. PS0.54±0.21 vs. 0.56±0.21 vs. 0.21±0.01 mN/mm, p < 0.05) and greater 3D cell alignment quantified by concentration parameter κ (ME vs. ML vs. PS3.13±0.33 vs. 2.96±0.80 vs. 1.97±0.25, p < 0.05) versus PS-ECTs. We selected ME-ECTs and determined the relationship between initial cell seeding number or density and ECT properties by comparing 6M, 9M, and 12M cells and 12M cells at doubled density (12MH). Increased initial cell number resulted in an increased dead cell ratio (9M11.2±6.0, 12M15.3±8.2, 12MH14.8±8.8%, p < 0.01 vs. 6M) and lower active stress (9M0.20±0.06, 12M0.18±0.06, 12MH0.29±0.11 mN/mm, p < 0.01 vs. 6M). Thus, construct geometry, seeding number, and density impact ECT structural and functional maturation. We then implanted a 6M-ME-ECT onto an infarcted athymic rat heart to explore therapeutic potential. Echocardiogram revealed higher ejection fraction (66.6±5.8 vs. 49.3±13.2%, p < 0.05) at four weeks after implantation compared to sham-operated controls. Masson’s trichrome staining also confirmed the reduction of scar area (11.6±7.6 vs. 23.9±7.2%, p < 0.05). Finally, we generated a larger (30x30 mm) ME-ECT and confirmed scalability.ConclusionScalable large-format ECTs are feasible for hiPSC-based preclinical and clinical cardiac regeneration paradigms.