Biomedical Engineering Reference
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differentiation and preconditioning of stem cells in the laboratory may be required
before transplanting them to the site of injury within the heart. Preconditioning of
these CD133+ cells with cytokines vascular endothelial growth factor-A (VEGF-A)
and brain-derived nerve growth factor (BDNF) enhances the angiomyogenesis. One
drawback is the possible rejection of fetal stem cell transplant. To explore the pos-
sibility of autologous stem cell therapy, researchers are investigating to find if
human adult livers might bear traces of CD133+ stem cells or stimulation of bone
marrow stem cells with these same growth factors might also generate myocytes
and angiogenic cells.
Expansion of Adult Cardiac Stem Cells for Transplantation
In human and animal studies, scientists at Johns Hopkins (Baltimore, MD) have
developed a fast and safe method for collecting cardiac stem cells (CSCs) from
small amounts of biopsied heart tissue obtained through cardiac catheterization in
patients undergoing treatment for heart failure. CSCs are expanded in the labora-
tory to produce enough cells within 4 weeks that can be used to repair heart tissue
clinically. The resulting clusters, called cardiospheres, contain cells that retain the
ability to regenerate themselves, and to develop into more specialized heart cells
that can conduct electrical currents and contract like the heart muscle should. These
findings, if confirmed in further clinical trials, could offer patients a means of using
their own SCCs to repair heart tissue soon after they have suffered a myocardial
infarction, or to regenerate weakened muscle resulting from heart failure, perhaps
averting the need for heart transplants. Use of a person's own adult CSCs instead
of those from a donor avoids the risk of triggering an immune response that could
cause rejection.
In rats subjected coronary occlusion, intravascular injection of CSCs after rep-
erfusion limits infarct size, and ameliorates left ventricular function (Dawn et al.
2005
). This study demonstrated that CSCs are effective when delivered in a clini-
cally relevant manner, a clear prerequisite for clinical application, and that these
beneficial effects are independent of cell fusion. The results establish CSCs as
candidates for cardiac regeneration and support an approach in which the heart's
own stem cells could be collected, expanded, and stored for subsequent therapeutic
repair.
Role of MSCs in Growth of CSCs
Mesenchymal stromal cells (MSC) are present in the adult mouse heart. They can
be isolated from the mouse heart and promote growth and differentiation of adult
CSC (Lushaj et al.
2010
). These findings could have a significant beneficial impact
on future heart failure treatment. Coculture and co-implantation of cardiac-derived
MSC with adult CSC could provide extensive cardiac regeneration and mainte-
nance of the CSC population after implantation into the heart.
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