20
Bacterial Cellulose
Influence.of.Oxygen.Availability.on.Tube.Formation. ................................. 36
Properties.and.Components.of.CSL............................................................... 37
Conclusion.and.Future.Perspectives. .................................................................. 38
Acknowledgments................................................................................................. 39
References. ............................................................................................................... 39
New.materials.that.are.not.thrombogenic.and.have.mechanical.properties.
that.mimic.the.native.blood.vessel.are.in.very.great.demand..Nanocellulose.
produced.by.the.bacteria.Gluconacetobacter xylinus.is.a.biomaterial.that.has.
gained. interest. in. the. field. of. tissue. engineering. because. of. its. unique.
properties,.such.as.great.mechanical.strength,.high.water.content.(around.
99%),.and.the.ability.to.be.shaped.into.three-dimensional.structures.during.biosynthesis..The.fabrication.process.of.bacterial.nanocellulose.(BNC).
vascular.grafts.is.very.unique.because.the.material.synthesis.and.product.
formation. takes. place. simultaneously.. The. bio. mechanical. performance,.
which. includes. rupture. pressure. and. compliance. along. with. biological.
response. (endothelialization,. blood. compatibility,. etc.),. is. dependent. on.
the.morphology.of.a.fibrillar.network..The.network.formation.is.affected.
by.cellulose.assembly.and.bacteria.motion,.proliferation.rate,.and.other.
factors..An.understanding.of.the.effects.of.cultivation.conditions.on.BNC.
network.formation.is.therefore.of.great.importance.
Introduction
The. network. of. cellulose. nanofibrils. produced. by. the. acetic. acid. bacteria. Gluconacetobacter xylinus. creates. a. biomaterial. with. great. mechanical.
strength,.high.water.content.(around.99%),.and.the.ability.to.be.shaped.into.
three-dimensional. (3D). structures. during. biosynthesis.. Cultivation. can. be.
done.in.the.presence.of.molds.and.porogens.of.different.sizes.and.shapes,.
which.makes.it.possible.to.design.desirable.biomaterial.geometries..Bacterial.
nanocellulose. (BNC). has. been. used. in. wound. healing. applications. (Wei.
et. al.. 2011;. Zhang. et. al.. 2010),. cartilage. repair. (Svensson. et. al.. 2005),. bone.
regeneration. (Zaborowska. et. al.. 2010),. and. most. recently,. for. blood. vessel.
replacements.(Wippermann.et.al..2009)..The.focus.of.this.review.will.be.on.
the.development.of.tubular.cellulose.scaffolds.for.use.as.small-caliber.artificial.blood.vessels.(see.Figure 2.1).
Cardiovascular. disease. is. the. major. cause. of. death. and. morbidity. in.
Western.countries..Surgical.bypass.with.autologous.grafts.remains.the.most.
used. treatment.. However,. many. patients. in. need. of. reconstruction. of. their.
vascular.system,.either.in.the.heart,.lower.extremities,.or.other.locations,.do.
not.have.suitable.vessels.due.to.preexisting.vascular.disease.or.amputation..
Approximately.5%–10%.of.all.patients.that.need.coronary.bypass.need.a.good.
Bacterial Cellulose
Influence.of.Oxygen.Availability.on.Tube.Formation. ................................. 36
Properties.and.Components.of.CSL............................................................... 37
Conclusion.and.Future.Perspectives. .................................................................. 38
Acknowledgments................................................................................................. 39
References. ............................................................................................................... 39
New.materials.that.are.not.thrombogenic.and.have.mechanical.properties.
that.mimic.the.native.blood.vessel.are.in.very.great.demand..Nanocellulose.
produced.by.the.bacteria.Gluconacetobacter xylinus.is.a.biomaterial.that.has.
gained. interest. in. the. field. of. tissue. engineering. because. of. its. unique.
properties,.such.as.great.mechanical.strength,.high.water.content.(around.
99%),.and.the.ability.to.be.shaped.into.three-dimensional.structures.during.biosynthesis..The.fabrication.process.of.bacterial.nanocellulose.(BNC).
vascular.grafts.is.very.unique.because.the.material.synthesis.and.product.
formation. takes. place. simultaneously.. The. bio. mechanical. performance,.
which. includes. rupture. pressure. and. compliance. along. with. biological.
response. (endothelialization,. blood. compatibility,. etc.),. is. dependent. on.
the.morphology.of.a.fibrillar.network..The.network.formation.is.affected.
by.cellulose.assembly.and.bacteria.motion,.proliferation.rate,.and.other.
factors..An.understanding.of.the.effects.of.cultivation.conditions.on.BNC.
network.formation.is.therefore.of.great.importance.
Introduction
The. network. of. cellulose. nanofibrils. produced. by. the. acetic. acid. bacteria. Gluconacetobacter xylinus. creates. a. biomaterial. with. great. mechanical.
strength,.high.water.content.(around.99%),.and.the.ability.to.be.shaped.into.
three-dimensional. (3D). structures. during. biosynthesis.. Cultivation. can. be.
done.in.the.presence.of.molds.and.porogens.of.different.sizes.and.shapes,.
which.makes.it.possible.to.design.desirable.biomaterial.geometries..Bacterial.
nanocellulose. (BNC). has. been. used. in. wound. healing. applications. (Wei.
et. al.. 2011;. Zhang. et. al.. 2010),. cartilage. repair. (Svensson. et. al.. 2005),. bone.
regeneration. (Zaborowska. et. al.. 2010),. and. most. recently,. for. blood. vessel.
replacements.(Wippermann.et.al..2009)..The.focus.of.this.review.will.be.on.
the.development.of.tubular.cellulose.scaffolds.for.use.as.small-caliber.artificial.blood.vessels.(see.Figure 2.1).
Cardiovascular. disease. is. the. major. cause. of. death. and. morbidity. in.
Western.countries..Surgical.bypass.with.autologous.grafts.remains.the.most.
used. treatment.. However,. many. patients. in. need. of. reconstruction. of. their.
vascular.system,.either.in.the.heart,.lower.extremities,.or.other.locations,.do.
not.have.suitable.vessels.due.to.preexisting.vascular.disease.or.amputation..
Approximately.5%–10%.of.all.patients.that.need.coronary.bypass.need.a.good.