In vivo, vascularized, functional, 3-dimensional cardiac tissue engineering

Abstract

Abstract Introduction: Engineering cardiac tissue in three dimensions is limited by the ability to supply nourishment to cells in the center of the construct. This study describes a method of engineering contractile three dimensional cardiac tissue with the incorporation of an intrinsic vascular supply. Methods: Silicone tubes were filled with a suspension of neonatal cardiac myocytes in fibrin gel, and surgically placed around the femoral artery and vein of adult rats. At three weeks, the tissues in the chambers were harvested for in vitro contractility evaluation and processed for histologic analysis. Results: By three weeks, the chambers had become filled with living tissue. HandE staining showed large amounts of surviving muscle tissue. Electron micrographs revealed well-organized contractile machinery and a high degree of intercellular connectivity. Immunostaining for vonWillebrand factor demonstrated neovascularization throughout the constructs. With electrical stimulation, the constructs were able to generate an average active force of 263 micronewtons (n = 5) with a maximum of 849 micronewtons. Electrical pacing was successful without fatigue at frequencies of 1 to 5 Hz. In addition, the constructs exhibited positive inotropy in response to the addition of ionic calcium and positive chronotropy in response to epinephrine. Conclusions: As engineering of cardiac replacement tissues proceeds, vascularization is an increasingly important component in the development of three-dimensional structures. This study demonstrates the in vivo survival, vascularization, organization and functionality of transplanted myocardial cells.