Engineered heart tissue graft derived from somatic cell nuclear transferred embryonic stem cells improve myocardial performance in infarcted rat heart.

The concept of regenerating diseased myocardium by implanting engineered heart tissue (EHT) is intriguing. Yet it was limited by immune rejection and difficulties to be generated at a size with contractile properties. Somatic cell nuclear transfer is proposed as a practical strategy for generating autologous histocompatible stem (nuclear transferred embryonic stem [NT-ES]) cells to treat diseases. Nevertheless, it is controversial as NT-ES cells may pose risks in their therapeutic application. EHT from NT-ES cell-derived cardiomyocytes was generated through a series of improved techniques in a self-made mould to keep the EHTs from contraction and provide static stretch simultaneously. After 7 days of static and mechanical stretching, respectively, the EHTs were implanted to the infarcted rat heart. Four weeks after transplantation, the suitability of EHT in heart muscle repair after myocardial infarction was evaluated by histological examination, echocardiography and multielectrode array measurement. The results showed that large (thickness/diameter, 2-4 mm/10 mm) spontaneously contracting EHTs was generated successfully. The EHTs, which were derived from NT-ES cells, inte grated and electrically coupled to host myocardium and exerted beneficial effects on the left ventricular function of infarcted rat heart. No teratoma formation was observed in the rat heart implanted with EHTs for 4 weeks. NT-ES cells can be used as a source of seeding cells for cardiac tissue engineering. Large contractile EHT grafts can be constructed in vitro with the ability to survive after implantation and improve myocardial performance of infarcted rat hearts.

Creation of engineered cardiac tissue in vitro from mouse embryonic stem cells.

BACKGROUND: Embryonic stem (ES) cells can terminally differentiate into all types of somatic cells and are considered a promising source of seed cells for tissue engineering. However, despite recent progress in in vitro differentiation and in vivo transplantation methodologies of ES cells, to date, no one has succeeded in using ES cells in tissue engineering for generation of somatic tissues in vitro for potential transplantation therapy. METHODS AND RESULTS: ES-D3 cells were cultured in a slow-turning lateral vessel for mass production of embryoid bodies. The embryoid bodies were then induced to differentiate into cardiomyocytes in a medium supplemented with 1% ascorbic acid. The ES cell-derived cardiomyocytes were then enriched by Percoll gradient centrifugation. The enriched cardiomyocytes were mixed with liquid type I collagen supplemented with Matrigel to construct engineered cardiac tissue (ECT). After in vitro stretching for 7 days, the ECT can beat synchronously and respond to physical and pharmaceutical stimulation. Histological, immunohistochemical, and transmission electron microscopic studies further indicate that the ECTs both structurally and functionally resemble neonatal native cardiac muscle. Markers related to undifferentiated ES cell contamination were not found in reverse transcriptase-polymerase chain reaction analysis of the Percoll-enriched cardiomyocytes. No teratoma formation was observed in the ECTs implanted subcutaneously in nude mice for 4 weeks. CONCLUSIONS: ES cells can be used as a source of seed cells for cardiac tissue engineering. Additional work remains to demonstrate engraftment of the engineered heart tissue in the case of cardiac defects and its functional integrity within the host's remaining healthy cardiac tissue.