Biomedical Engineering Reference
In-Depth Information
cell-dense tissues were composed of cardiac cells. Additionally,
the diffuse localization of connexin-43 throughout the cardiac
tissues also suggested gap junction formations within the grafts.
TEM confirmed the presence of functional microvessels containing
red blood cells within the lumen found throughout the aortic
replacement grafts. The results from TEM also showed the existence
of well-differentiated myocardial tissue within the beating tubes,
possessing numerous mitochondria, as well as myofilaments with
elongated sarcomeres. Furthermore, when myocardial tubes used
for aortic replacement were compared to grafts simply implanted
in the abdominal cavity of an animal model, the aortic replacement
model showed significantly thicker tissue, and the expression
of brain natriuretic peptide, myosin heavy chain-α, and myosin
heavy chain-β was also observed. These results also suggested that
pulsation due to host blood flow within the lumen of the myocardial
tubes had a profound effect on stimulating cardiomyocyte
hypertrophy and growth. Previous studies have demonstrated that
mechanical stress has the ability to induce myocardial hypertrophy
during both developmental and pathologic states. In myocardial
tissue engineering, researchers have applied these phenomena to
accelerate cardiomyocyte hypertrophy by mechanical stretching.
Therefore, the application of mechanical loads either in vitro or in
vivo seems to be an essential factor in the engineering of functional
tissues. These results demonstrate the next step of myocardial tissue
reconstruction and a shift toward the fabrication of independently
functioning cardiac structures having the potential to act as tissue-
engineered cardiac-assist devices.
6d.4
Future Perspective
The challenge to engineer organ-like tissues is an exciting new
avenue for regenerative therapies. Although this challenge has only
been performed on a small scale, the future solutions for problems
of cell source and scaling up provide a more powerful construction,
resulting in the development of remarkable tissue-engineered
cardiac-assist devices or even organ replacement.
Insufficient oxygen perfusion into engineered 3D myocardial
constructs remains a major obstacle in myocardial tissue
engineering, which limits the construct thickness to approximately
