Biomedical Engineering Reference
In-Depth Information
humans is uncertain, despite numerous
in vivo
animal studies. To date,
there are still no TEBVs approved for clinical use by the FDA. The ambi-
tious goal of manufacturing 'off-the-shelf' grafts, resembling the naturally
occurring vasculature in structure and function, remains distant as a number
of issues remain unresolved.
There is no substantial evidence confi rming whether constructs with mul-
tiple layers, akin to the tunicae intima, media and adventitia of naturally
occurring vessels, are preferable to sheet-based tissue engineering. Although
many scaffold varieties have been manufactured from both synthetic mate-
rials and biopolymers, none of these constructs is regularly used by a broad
cohort of groups seeking to manufacture TEBVs. The presence of mature,
healthy vascular cells in naturally occurring arteries is important to their
structure and function, which are directly associated with CVS homeostasis.
The employment of mature vascular cells such as ECs and SMCs in TEBVs
is thought to be critical, particularly when attempting to achieve an anti-
thrombotic luminal layer. The routine seeding of ECs onto synthetic con-
duits prior to their implantation is not, however, commonplace. Intensive
investigation is still required into stem cells before their exciting potential
as a substitute for mature vascular cells is realised (Deb and Patterson,
2010). There are also ethical issues to resolve before stem cells are routinely
employed in TEBVs.
Once 'off-the-shelf' TEBVs are successfully, consistently and safely
deployed, humanity's cardiovascular health will benefi t immensely. In the
process, our understanding of cardiovascular pathology will expand. The
investigative techniques mastered may be employed in other tissue engi-
neering applications and may also prove useful in examining conditions
requiring urgent attention such as cancer.
12.9 References
ABBOTT, W.M., MEGERMAN, J., HASSON, J.E., L'ITALIEN, G., and WARNOCK, D.F. (1987).
Effect of compliance mismatch on vascular graft patency.
J Vasc Surg
5
,
376-382.
AIRD, W.C. (2007). Phenotypic heterogeneity of the endothelium: II. Representative
vascular beds.
Circulation Res
100
, 174-190.
ALLAIRE, E., BRUNEVAL, P. , MANDET, C., BECQUEMIN, J.P., and MICHEL, J.B. (1997). The
immunogenicity of the extracellular matrix in arterial xenografts.
Surgery
122
,
73-81.
ALSBERG, E., VON RECUM, H.A., and MAHONEY, M.J. (2006). Environmental cues to guide
stem cell fate decision for tissue engineering applications.
Expert Opin Biolog
Therapy
6
, 847-866.
AMIEL, G.E., KOMURA, M., SHAPIRA, O., YOO, J.J., YAZDANI, S., BERRY, J., KAUSHAL, S.,
BISCHOFF, J., ATALA, A., and SOKER, S. (2006). Engineering of blood vessels from
acellular collagen matrices coated with human endothelial cells.
Tissue Eng
12
,
2355-2365.
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