Biomedical Engineering Reference
In-Depth Information
Fig. 9 Functional tissues may be regenerated by designing sophisticated polymeric sys-
tems that supply growth factors in a sustained and localized fashion inspired by normal
biologic mechanisms, while exhibiting appropriate physicochemical properties
4.1
Therapeutic Angiogenesis
4.1.1
Therapeutic Significance of VEGF
Coronary heart disease, which involves the blockage of coronary arteries and
thus reduced blood flow, is the leading cause of death in the United States.
Itaccountsformorethanonequarterofalldeathseachyear.Currenttreat-
ment options to restore perfusion include lifestyle changes, medication, and
invasive surgical procedures [140-142]. However, these approaches are often
either restricted to moderately diseased patients or suffer from limitations
such as frequent re-narrowing of arteries at later times. The development
of alternative strategies may allow better treatment options for patients, and
therapeutic angiogenesis, the promotion of blood vessel formation in is-
chemic tissues, holds great potential as one treatment for cardiovascular
occlusive diseases.
Current approaches to therapeutically administer VEGF, either as recom-
binant protein or by gene transfer, have yielded promising results in an-
imal models and small-scale clinical trials; however, larger trials failed to
clearly demonstrate efficacy [16, 143, 144]. In many of these studies recom-
binant VEGF has been delivered as a single growth factor through bolus
injection [143, 145, 146]. Since the elimination half-life of VEGF is approxi-
mately 1 h, this approach results in only a temporary supply of the growth
factor [147]. Furthermore, spatially confined presentation of growth factors
is not achieved with this approach, as highlighted by the finding that injected
 
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