Creation of myocardial tubes using cardiomyocyte sheets and an in vitro cell sheet-wrapping device

Regenerative medicine involving injection of isolated cells and transplantation of tissue-engineered myocardial patches, has received significant attention as an alternative method to repair damaged heart muscle. In the present study, as the next generation of myocardial tissue engineering we demonstrate the in vitro fabrication of pulsatile myocardial tubes using cell sheet engineering technologies. Three neonatal rat cardiomyocyte sheets, which were harvested from temperature-responsive culture dishes, were wrapped around fibrin tubes using a novel cell sheet-wrapping device. The tubular constructs demonstrated spontaneous, synchronized pulsation within 3 h after cell sheet wrapping. Contractile force measurements showed that the contractile force increased in accordance with both increasing rest length (Starling mechanism) and increasing extracellular Ca2+ concentration. Furthermore, the tissue-engineered myocardial tubes presented measurable inner pressure changes evoked by tube contraction (0.11±0.01 mmHg, max 0.15 mmHg, n=5). Histological analyses revealed both well-differentiated sarcomeres and diffuse gap junctions within the myocardial tissues that resembled native cardiac muscle. These data indicate that tissue-engineered myocardial tubes have native heart-like structure and function. These new myocardial tissue constructs should be useful for future applications in physiological studies and pharmacological screening, and present a possible core technology for the creation of engineered tissues capable of independent cardiac assistance.