Biomedical Engineering Reference
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Figure 17.3. Stability of the growth stimulation activity of collagen-
binding EGF. Fresh proteins or proteins stored at 4 C for 30 days in cul-
ture medium (left graph) or bound to collagen-coated wells (right graph)
were applied to culture of human dermal fibroblasts (48-well plate). Filled
column, day 0; open column, day 30. Cell growth activity was evaluated at
seven days of culture using a WST1 colorimetric assay (absorbance at 450-
650 nm; mean
±
SD).
vessels after balloon-catheter injury. The application of CBD-HGF to
the injured area enhances reendothelialization. 28
Growth factors directly fused to collagen or other matrix pro-
teins may represent the ultimate binding protein. Hayashi et al . 29
produced a fusion protein of EGF and type III collagen that adopts a
triple helical structure, similarly to native collagen. This fusion pro-
tein can be incorporated into collagen fibrils to allow the prepara-
tion of collagen material that includes EGF.
17.3.2 Fibrin-Binding Growth Factors
Fibrin is an abundant protein present on the surface of injured
tissues. In addition, it has been studied as a material for tissue
engineering scaffolds. Therefore, growth factors with fibrin-binding
a nity are considered useful for tissue regeneration. Sakiyama-
Elbert et al . 30 produced a fusion protein between NGF and a
short polypeptide of the α 2-plasmin inhibitor ( α 2-pI); the activated
coagulation factor XIII (FXIIIa) mediated the cross-linking of this
sequence to fibrin. In addition, a plasmin cleavage sequence was
inserted between the α 2-pI sequence and the growth factor. The
fusion protein (TG-P-NGF) was incorporated into fibrin clots by
FXIIIa and was then released by plasmin when the tissues started
 
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