Biomedical Engineering Reference
In-Depth Information
Otto et al. attempted to make a whole working heart using
decellularized rat hearts, which were prepared with detergents
through coronary perfusion, and obtained a perfusable accellular
vascular construct with chambers and valves by preserving the
myocardium matrix. They recellularized this construct with
neonatal rat cardiac cells or rat aortic endothelial cells and showed
that it had contractile abilities. The pump function showed that the
left ventricular pressure was recorded up to 2.4 mm Hg at eight days
after cultivation. This approach has the potential to solve the blood
supply problem to engrafted cells by retaining the natural structures
and guiding the formation of vessels [7].
6d.3
Cell Sheet-Based Cardiac Pumps
In contrast to scaffold-based cardiac pumps, we have successfully
fabricated a beating cardiac tube in vitro using temperature-
responsive culture dishes and an original cell sheet-wrapping
device. Triple neonatal rat cardiac cell sheets were harvested from
temperature-responsive culture surfaces and wrapped around
fibrin tubes. Our in vitro-fabricated beating cardiac tube showed
spontaneously synchronized pulsations at the macroscopic level.
We also confirmed an increased rest length and the inotropic effects
of increased Ca
2+
concentrations. Additionally, the cardiac tubes
presented measurable inner pressure changes in response to the
spontaneous tube contraction. The mean inner pressure gradient
was 0.11 mmHg [8]. Subsequently, we fabricated an implantable
tube-shaped myocardial tissue by wrapping a neonatal rat cardiac
cell sheet around a resected adult rat thoracic aorta and transplanted
it into the abdominal aorta of athymic rats [9]. Four weeks after
transplantation, the engineered myocardial tubes demonstrated
spontaneous and synchronous pulsations independent of the
host heartbeat macroscopically. Detection of electrical potentials
confirmed that the spontaneous electrical excitation spikes were
independent of the host heartbeat. Independent graft pressures
were observed with a magnitude of 5.9 mm Hg due to their
independent pulsations. Histological examination and transmission
electron microscopy (TEM) showed that the engineered beating
tubes were composed of cardiac tissues that resembled the native
heart. Immunostaining for troponin-T revealed that the stratified
