Biomedical Engineering Reference
In-Depth Information
17.4.2.1 Materials that induce angiogenesis
Fibrin-binding VEGF121 ( α 2PI1-8-VEGF121) mixed with fibrin
exhibits e cacious angiogenic properties, as assessed using a
chorioallantoic membrane (CAM) assay 34 : the blood vessel density
in the presence of fibrin-binding VEGF121 was approx 1.5 times
higher than that induced by native VEGF121. In addition, α 2PI1-
8-VEGF121 induces the formation of nonleaky vessels on a Teflon
chamber coated with fibrin andsubcutaneously implanted.
Implantable scaffolds combined with collagen-binding growth
factors have also been studied. Vessel migration into collagen scaf-
folds is enhanced by CBD-bFGF, 21 although the collagen-binding
a nitydoesnotvarymuchbetweennativebFGFandCBD-bFGF.The
difference in the angiogenic effect between native and engineered
bFGFswasapparentatsevendaysbutnotatfourdays,afterimplan-
tation.Collagen-bindingHGF(CBD-HGF) 26 alsoenhancesbloodves-
sel migration into subcutaneously implanted collagen sponges that
are combinedwiththe fusion protein.
17.4.2.2 Artificial blood vessel and heart valve
Extended polytetrafluoroethylene (ePTFE) is used as the material
for small-caliber artificial blood vessels. Figure 17.4a shows our
preliminary design of artificial blood vessels with HGF activity; an
ePTFE sheet was treated serially with an amphiphilic polymer and
collagen and was then combined with CBD-HGF. Endothelial cells of
the human coronary artery grew only on the surface, where CBD-
HGF ispresent (Fig. 17.4b).
The effect of the application of CBD-HGF on endothelializa-
tion of implant materials was further studied. Porcine heart valves
that were decellularized (i.e., mainly composed of collagen) were
combined with CBD-HGF. 48 Endothelialization of the valves after
implantation into a dog pulmonary artery was enhanced by CBD-
HGF. Earlier coverage of valve surfaces by endothelial cells may
prevent surface thrombosis and contribute to the durability of the
implants.
A sheet of collagen preparation (decellularized porcine urinary
bladder matrix) was combined with CBD-HGF and implanted into
 
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