Biomedical Engineering Reference
In-Depth Information
A scaffold-based, three-dimensional, human dermal fibroblast culture (3DFC)
has been tested as a cardiac patch to stimulate revascularization and preserve left
ventricular function following infarction in severe combined immunodeficient
(SCID) mice (Kellar et al.
2005
). The 3DFC contains viable cells that secrete
angiogenic growth factors and has been previously shown to stimulate angiogene-
sis. These results show that the 3DFC as a cardiac patch functioned to attenuate
further loss of left ventricular function accompanying acute myocardial infarct, and
that this may be related in part to myocardial revascularization.
Cardiac Repair with Myoendothelial Cells from Skeletal Muscle
A novel population of myoendothelial cells have recently been identified and puri-
fied from human skeletal muscle. These cells coexpress myogenic and endothelial
cell markers and produce robust muscle regeneration when injected into cardio-
toxin-injured skeletal muscle (Okada et al.
2008
). Myoendothelial cells stimulated
the growth of new blood vessels in the heart and were more effective at repairing
the injured cardiac muscle and reducing scar tissue than previous approaches that
have used muscle myoblasts. At 6 weeks after injection, the myoendothelial cell-
injected hearts functioned 40-50% more effectively compared with hearts that had
been injected with myoblasts, thereby dramatically improving the function of the
injured left ventricle. These cells represent a novel cell population from human
skeletal muscle that may hold promise for cardiac repair as an autologous trans-
plant. This means that for a patient who suffers a heart attack, myoendothelial cells
can be isolated from a muscle biopsy, purified, and then reinjected into the injured
heart muscle, thereby avoiding any risk of rejection by introducing foreign cells.
Myocardial Tissue Engineering
Myocardial tissue engineering involves seeding cells in 3D matrices of biodegrad-
able polymers or cell sheet engineering without artificial scaffolds to form new
myocardial constructs. Functional assembly of engineered cardiac muscle can be
enhanced by oxygen supply provided by mechanisms resembling those in normal
vascularized tissues. To mimic the capillary network, cardiomyocytes and fibro-
blasts isolated from the neonatal rat hearts were cultured on a highly porous elas-
tomer with a parallel array of channels that were perfused with culture medium
(Radisic et al.
2006
). To mimic oxygen supply by hemoglobin, culture medium was
supplemented with a perfluorocarbon (PFC) emulsion; constructs perfused with
unsupplemented culture medium served as controls. Consistently, constructs culti-
vated in the presence of PFC contained higher amounts of DNA and cardiac bio-
markers (troponin I, connexin-43) and had significantly better contractile properties
as compared to control constructs. In both groups, electron microscopy revealed
open channels and the presence of cells at the channel surfaces as well as within
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