Tissue Engineering: Focus on the Cardiovascular System - Biomaterials Science: An Integrated Clinical and Engineering Approach - page 180

demonstrated to stimulate mature and functional blood vessel formation
in vivo [137]. Richardson et al. described a unique scaffold system deliver-
ing VEGF and PDGF-BB, each with distinct release kinetics. Only their co-
administration resulted in a synergistic effect in vivo, yielding mature, stable
vessels covered with smooth muscle cells [137]. Peters et al. demonstrated
that PLG scaffolds incorporating VEGF and seeded with human microvas-
cular endothelial cells significantly increased the density of host blood ves-
sels penetrating to the graft site within 7 days of implantation [138].
Conclusions
Engineering cardiac tissue represents a multidisciplinary, emerging field that
promises to regenerate diseased heart tissue. These techniques comprise novel
and experimental means for repairing infarcted myocardium and enhancing
cardiac function. Preclinical and clinical studies have determined the feasi-
bility and efficacy of the proposed methods yearning to enhance myocardial
functioning. However, significant levels of cell death or loss following cell
injection constitute one of the major obstacles facing researchers attempting
to design productive engraftment techniques. In this regard, the creation of
preformed cardiac construct or injectable-based biomaterial systems in tissue
engineering protocols is expected to have a notable impact on cell-delivery effi-
ciency. Biomaterials will allow for optimization of cell delivery and retention
while also providing for improved tissue formation in vitro, with enhanced
graft survival and functionality following implantation. Vascularization has
emerged as a prerequisite for designing large tissues in vitro and for enhanc-
ing graft survival following implantation by providing a robust source of
oxygen and nutrient supply as well as intracellular signaling critical to fur-
ther tissue development. While various vascularization strategies have been
described, the optimal method has yet to be defined. In summary, combina-
tion of the leading stem cell type, scaffolding biomaterial, and vascularization
techniques will allow for effective cardiac graft construction and cell therapy.
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