RESUMO
The purpose of this study was to fabricate pulsatile tubular cardiac tissue using cell sheet based-tissue engineering. First, we fabricated human induced pluripotent stem cell (hiPSc)-derived cardiomyocyte sheets and normal human dermal fibroblast (NHDF) sheets which are harvested from temperature responsive culture dishes only by lowering the temperature. Then tubular cardiac tissues are formed by wrapping one hiPSc-derived cardiomyocyte sheet and three NHDF sheets around an octagonal column, and both ends of the tubular tissue were covered with fibrin and collagen gel. The octagonal column with the tubular tissue was connected to an in vitro circulation system in a culture box. After four-day culture, the cardiac tissue survived and pulsated spontaneously in the circulation system. Furthermore, the analysis with a Millar catheter inserted into the cardiac tubes revealed significant inner pressure changes generated by their beating. In addition, the tubular cardiac tissue pulsated in response to the electrical stimulation. Although histological analyses demonstrated that cardiac troponin T-positive cells stratified the inner surface of the tubular tissues, gene expression analyses showed an immature state of these cardiomyocytes. Thus, cell sheet-based tissue engineering realized human pulsatile tubular cardiac tissue fabrication and we believe that these tubular cardiac tissues should contribute to future drug screening and regenerative therapy for heart diseases.
RESUMO
Safety concerns of ventricular tachyarrhythmia have arisen from some clinical trials of autologous skeletal myoblast (SkM) injection therapy. This study examined the effect and safety of SkM sheet therapy in a pig model of chronic myocardial infarction. Minipigs underwent LAD occlusion using a balloon catheter for 2 h, followed by reperfusion. After 28 days, 12 SkM sheets were transplanted onto the infarcted myocardium (sheet group n = 8); the same number of cells was also injected into the myocardium (injection group n = 7), and sham operations were performed as a control (sham group n = 7). Implantable ECG loop recorders (ILR) were placed subcutaneously on the left thorax. At 28 days after transplantation, we assessed cardiac function with MDCT, interrogated ILR, and performed programmed ventricular stimulation (PVS), after which organs were harvested for histopathology. To assess the inflammatory and injury response, inflammation factors and high-sensitive CRP and troponin I were measured at 1, 3, 7, and 28 days after transplantation by the cytokine array method and ELISA, respectively. The sheet group showed an improvement in cardiac function compared with both the injection and sham groups (LVEF change: 5.8 ± 2.7%, -1.0 ± 2.6%, and -3.8 ± 1.8% in the sheet, injection, and sham groups, respectively, p < 0.05). VF was not detected in any group using ILR, while VT was detected in one pig from the injection group. VF was induced in 25.0%, 71.4%, and 28.6% of animals in the sheet, injection, and sham groups, respectively. In the injection group, anti-macrophage-positive cells were observed around the injected cells within the myocardium. Transmission electron microscopic images showed differentiated myofilaments, collagen layers, and a characteristic extracellular matrix surrounding the SkMs in the sheet group. Toroponin I and IL-6 levels were higher in the injection group compared with both the sheet and sham groups. SkM sheets transplanted onto infarcted myocardium improved cardiac function over SkM injection without increasing arrhythmogenicity.
