Figure 5.1
93
Bacterial Cellulose Surface Modifications
(a)
(b)
(c)
(d)
(e)
(f )
Figure 5.1
SEM.micrographs.of.BC.treated.with.(a,.b).RGD-CBM,.(c,.d).CBM,.and.(e,.f).buffer..The.arrows.
mark.cells.with.an.elongated.morphology..(a,.c,.e).Scale.50.μm;.(b,.d,.f).scale.5.μm..(Reproduced.
from.Andrade.et.al..2010.)
proteins. (different. constructs. containing. CBM-RGD). and. tested. in. fibroblast.cell.cultures..The.results.showed.that.only.the.proteins.with.the.RGD.
sequence. significantly. improved. fibroblast. adhesion. as. compared. to. the.
unmodified.membrane.(Figure 5.1).
The. results. also. demonstrated. that. the. protein. containing. a. single. RGD.
copy. had,. surprisingly,. a. stronger. effect. than. the. protein. containing. two.
. copies.of.RGD..Another.work.from.the.same.group.showed.that.the.presence.
of. chimeric. peptides. (RGD. and. GRGDY). significantly. increases. the. adhesion.of.human.microvascular.endothelial.cells.(HMECs).on.BNC,.with.RGD.
showing.a.stronger.effect.than.GRGDY.(Figure 5.2).
Moreover,.the.presence.of.RGD.stimulated.elongation.of.the.cells.and.the.
early.formation.of.cordlike.structures,.however,.it.decreased.the.ingrowth.
of.these.endothelial.cells.through.the.BNC.(Andrade.et.al..2010)..In.a.recent.
work,.Andrade.et.al..(2011).studied.the.blood.compatibility.of.BNC.treated.
with.the.RGD-CBM.protein..The.presence.of.RGD.increased.platelet.adhesion,.probably.because.the.RGD.was.recognized.by.the.platelets’.integrins..
However,.when.endothelial.cells.were.cultured.on.RGD-treated.BNC,.a.confluent.cell.layer.was.formed.and.almost.no.platelets.adhered.to.the.. material.
(Figure 5.3).. Thus. the. improvement. of. BNC. blood. compatibility. through.
modification.with.adhesion.peptides.seems.to.be.an.interesting.strategy.for.
the.development.of.BNC.vascular.grafts.
folds,.Wan.et.al..(2011).developed.heparinized.membranes..Although.a.common. way. to. perform. heparinization. is. the. coating. process. where. heparin.
is. immobilized. on. the. surface. of. the. materials. by. ionic. binding,. the. early.
depletion. of. heparin. (leaving. a. heparin-free. material. behind). is. a. major.
93
Bacterial Cellulose Surface Modifications
(a)
(b)
(c)
(d)
(e)
(f )
Figure 5.1
SEM.micrographs.of.BC.treated.with.(a,.b).RGD-CBM,.(c,.d).CBM,.and.(e,.f).buffer..The.arrows.
mark.cells.with.an.elongated.morphology..(a,.c,.e).Scale.50.μm;.(b,.d,.f).scale.5.μm..(Reproduced.
from.Andrade.et.al..2010.)
proteins. (different. constructs. containing. CBM-RGD). and. tested. in. fibroblast.cell.cultures..The.results.showed.that.only.the.proteins.with.the.RGD.
sequence. significantly. improved. fibroblast. adhesion. as. compared. to. the.
unmodified.membrane.(Figure 5.1).
The. results. also. demonstrated. that. the. protein. containing. a. single. RGD.
copy. had,. surprisingly,. a. stronger. effect. than. the. protein. containing. two.
. copies.of.RGD..Another.work.from.the.same.group.showed.that.the.presence.
of. chimeric. peptides. (RGD. and. GRGDY). significantly. increases. the. adhesion.of.human.microvascular.endothelial.cells.(HMECs).on.BNC,.with.RGD.
showing.a.stronger.effect.than.GRGDY.(Figure 5.2).
Moreover,.the.presence.of.RGD.stimulated.elongation.of.the.cells.and.the.
early.formation.of.cordlike.structures,.however,.it.decreased.the.ingrowth.
of.these.endothelial.cells.through.the.BNC.(Andrade.et.al..2010)..In.a.recent.
work,.Andrade.et.al..(2011).studied.the.blood.compatibility.of.BNC.treated.
with.the.RGD-CBM.protein..The.presence.of.RGD.increased.platelet.adhesion,.probably.because.the.RGD.was.recognized.by.the.platelets’.integrins..
However,.when.endothelial.cells.were.cultured.on.RGD-treated.BNC,.a.confluent.cell.layer.was.formed.and.almost.no.platelets.adhered.to.the.. material.
(Figure 5.3).. Thus. the. improvement. of. BNC. blood. compatibility. through.
modification.with.adhesion.peptides.seems.to.be.an.interesting.strategy.for.
the.development.of.BNC.vascular.grafts.
folds,.Wan.et.al..(2011).developed.heparinized.membranes..Although.a.common. way. to. perform. heparinization. is. the. coating. process. where. heparin.
is. immobilized. on. the. surface. of. the. materials. by. ionic. binding,. the. early.
depletion. of. heparin. (leaving. a. heparin-free. material. behind). is. a. major.