Generation of a large-scale vascular bed for the in vitro creation of three-dimensional cardiac tissue.

Introduction: The definitive treatment for severe heart failure is transplantation. However, only a small number of heart transplants are performed each year due to donor shortages. Therefore, novel treatment approaches based on artificial organs or regenerative therapy are being developed as alternatives. We have developed a technology known as cell sheet-based tissue engineering that enables the fabrication of functional three-dimensional (3D) tissue. Here, we report a new technique for engineering human cardiac tissue with perfusable blood vessels. Our method involved the layering of cardiac cell sheets derived from human induced pluripotent stem cells (hiPSCs) on a vascular bed derived from porcine small intestinal tissue.

Methods: For the vascular bed, a segment of porcine small intestine was harvested together with a branch of the superior mesenteric artery and a branch of the superior mesenteric vein. The small intestinal tissue was incised longitudinally, and the mucosa was resected. Human cardiomyocytes derived from hiPSCs were co-cultured with endothelial cells and fibroblasts on a temperature-responsive dish and harvested as a cardiac cell sheet. A triple-layer of cardiac cell sheets was placed onto the vascular bed, and the resulting construct was subjected to perfusion culture in a bioreactor system.

Results: The cardiac tissue on the vascular bed pulsated spontaneously and synchronously after one day of perfusion culture. Electrophysiological recordings revealed regular action potentials and a beating rate of 105 ± 13/min (n = 8). Furthermore, immunostaining experiments detected partial connection of the blood vessels between the vascular bed and cardiac cell sheets.

Conclusions: We succeeded in engineering spontaneously beating 3D cardiac tissue in vitro using human cardiac cell sheets and a vascular bed derived from porcine small intestine. Further development of this method might allow the fabrication of functional cardiac tissue that could be used in the treatment of severe heart failure.