Endothelial Progenitor Cells—Potential New Avenues to Improve Neoangiogenesis and Reendothelialization - International Review of Cell and Molecular Biology - page 69

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. To use EPC in a preseeding and in vivo implantation approach to form specific
tissue .
As mentioned earlier, the biggest problem for TE constructs remains
vascularity. To improve the survival of implanted structures such as der-
mal substitutes, EPCs have been used to augment revascularization
( Kung et al., 2008 ). This concept has also been used for the improvement
of TE of the bladder ( Chen et al., 2011a ). EPCs have been found in these
cases to be actively involved in the formation of new vessels.
In summary ( Section 5 ), in vitro and in vivo studies have been performed to
explore the possibilities of EPC-based therapies. Moreover, EPCs are used
more and more to solve the problems encountered in TE as well as in appli-
cations to reduce problems after cardiological interventions (e.g., EPC-
capturing stent). But still no therapy has shown such a significant improve-
ment that would lead to a broad implementation of EPC in clinical
daily practice.

6. CONCLUSIONS
EPCs have been shown to amply contribute to the revascularization of
ischemic areas. The discovery of EPC has substantively altered our view of
adult tissue angiogenesis, indicating that circulating BM-derived cells can
contribute to new blood vessel formation. However, after 15 years of
vigorous research, no consensus about the appearance of EPC has been
reached yet. It is widely accepted that EPCs promote angiogenesis and
vasculogenesis by virtue of the release of paracrine angiogenic factors, which
they carry with them as cargo.
Until now, it is known that EPCs are a subset of MNCs that are mobi-
lized from BM by endocrine and paracrine effects. EPCs home to sites of
vascular injury and can form vascular networks in vivo and in vitro . Further-
more, EPC can be subdivided into several subgroups that are termed CAC,
ECFC, or CFU, with CFU being more of a unit holding EPC and other cell
types. The identification of EPC or their subtypes is until now not really
standardized, whereby the comparison of different EPC-based research
efforts becomes often difficult or impossible.
EPCs are supposed to originate from the hemangioblast, an early hem-
angiogenic precursor cell that is supposed to be located in the BM during the
embryonal phase. The exact function of EPC is until now also hypothesized
as a cell that gives rise to newly formed vessels in situ or as an adjunct to ECs