Cell Therapy for Cardiovascular Disorders - Applications of Biotechnology in Cardiovascular Therapeutics - page 202

Targeted Delivery of Endothelial Progenitor Cells
Labeled with Nanoparticles
Circulating endothelial progenitor cells (EPCs) are involved in physiological pro-
cesses such as vascular re-endothelialization and postischemic neovascularization.
However, the success of cell therapies depends on the ability to deliver the cells to
the site of injury. Human EPCs labeled with iron oxide superparamagnetic nano-
particles, could be targeted to site of common carotid artery injury in rats using an
externally applied magnetic device (Kyrtatos et al. 2009 ). There was a fivefold
increase in EPC localization at the site of vascular injury at 24 h after implantation
in vivo.
Fetal Cardiomyocytes Seeding in Tissue-Engineered
Cardiac Grafts
The synthetic materials currently available for the repair of cardiac defects are
nonviable, do not grow as the child develops, and do not contract synchronously
with the heart. To overcome this problem Genzyme and surgeons at the Toronto
General Hospital (Toronto, Canada) developed a beating patch by seeding fetal
cardiomyocytes in a biodegradable scaffold in vitro. A gelatin patch was used to
replace the right ventricular outflow tract in syngeneic rats. The seeded cells sur-
vived in the right ventricular outflow tract after the scaffold dissolved 12 weeks
after implantation. In addition, the unseeded patches encouraged the ingrowth of
fibrous tissue as the scaffold dissolved and the patches remained completely
endothelialized. Clinical trials are planned with the autologous bioengineered
cardiac graft.
UCB Progenitor Cells for Engineering Heart Valves
Engineering of biologically active heart valve leaflets using prenatally available
human UCB-derived progenitor cells as the only cell source has been demonstrated
(Schmidt et al. 2006 ). Wharton's Jelly derived cells and UCB-derived endothelial
progenitor cells were subsequently seeded on biodegradable scaffolds and cultured
in a biomimetic system under biochemical or mechanical stimulation or both.
Depending on the stimulation, leaflets showed mature layered tissue formation with
functional endothelia and extracellular matrix production comparable with that of
native tissues. This demonstrates the feasibility of heart valve leaflet fabrication
from prenatal UCB-derived progenitor cells as a further step in overcoming the lack
of living autologous replacements with growth and regeneration potential for the
repair of congenital malformations.