Biomedical Engineering Reference
In-Depth Information
QD-based.contrast.agents.can.be.utilized.in.many.biomedical.applications,.such.as.tumor.
targeting.and.imaging,
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.lymph.node.mapping,
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.and.vascular.imaging.
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2.8 CellularFateTrackinginDevelopmentalBiology
Developmental.biology.is.among.the.rapidly.growing.and.interesting.ields.in.biology.that.
study.the.initiation.and.maturation.of.living.organisms..It.can.integrate.different.levels.of.
biology,.such.as.molecular.biology,.physiology,.cell.biology,.genetics,.etc.,.so.that.the.study.
of.development.is.indispensable.for.a.better.understanding.of.different.ields.in.biology..
Development.is.a.progressive.process.in.which.a.single.cell.is.able.to.generate.a.multicellu-
lar.organism.with.different.cell.types..Therefore,.producing.cellular.diversity.within.each.
generation.is.one.of.the.main.goals.followed.during.development,.which.leads.to.several.
fundamental.questions,.such.as:.How.can.a.single.cell.differentiate.into.hundreds.of.dif-
ferent.cell.types?.Which.cell.in.an.early-stage.embryo.will.inally.develop.into.which.part.
of.the.inal.creature?
Because.of.QDs.exceptional.photostability,.symmetrical.diffusion.among.daughter.cells.
during.cell.divisions,.and.remaining.within.labeled.cells,.these.nanoparticles.can.be.effec-
tively. exploited. for. labeling. early-stage. embryonic. cells. in. order. to. perform. in. vivo. fate.
mapping. and. monitoring. of. migration. and. differentiation. of. individual. cells,. which. is.
still.unachievable.with.currently.available.tracing.agents..In.an.elegant.set.of.experiments.
designed. by. Dubertret. et. al.,. micelle-encapsulated. CdSe-ZnS. QDs. were. microinjected.
into.individual.cells.in.early-stage.
Xenopus
.embryos..In.particular,.the.QD.micelles.were.
equally. transferred. to. daughter. cells,. and. they. were. highly. stable. and. compatible. with.
normal.embryonic.development,.resulting.in.real-time.monitoring.of.cell.lineage.and.dif-
ferentiation.up.to.the.tail.bud.stage.
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.The.embryonic.development.of.zebra.ish.as.the.ver-
tebrate.model.organism.has.also.been.studied.by.Rieger's.group
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.due.to.its.optical.clarity,.
external.development,.and.ease.of.manipulation..Red.light-emitting.QDs.have.been.coin-
jected.with.mRNA-encoding.GFP,.an.established.lineage.tracer.in.zebra.ish.embryos,.into.
individual.blastomeres.at.the.32-.and.64-cell.stage..The.results.demonstrated.that.QDs.can.
reliably.mark.a.large.subfraction.of.the.descendants,.besides.the.injected.embryos,.to.up.to.
10
8
.QDs/cell,.did.not.show.any.malformations.or.developmental.problems.during.embryo-
genesis..In.another.study,.QDs.coated.with.commercial.phospholipids.were.electroporated.
into.mouse.embryonic.neural.stem.and.progenitor.cells.(NSPCs)..Consequently,.QD.label-
ing.had.no.adverse.effects.on.the.normal.developmental.ability.of.such.cells.either.in.vitro.
or.in.utero.following.implantation.of.the.labeled.embryos..Using.an.in.utero.ultrasound-
guided.electroporation.system,.Slotkin.et.al..revealed.that.the.labeled.NSPCs.were.able.to.
survive,.migrate,.and.differentiate.into.nervous.system.lineages.
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.These.studies.demon-
strated. that. QDs. are. favorably. stable. in. physiological. conditions,. and. are. biocompatible.
with.the.highly.controlled.and.sensitive.process.of.embryonic.development,
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.which.makes.
them.promising.intravital.lineage.tracer.agents.for.analyzing.many.aspects.of.embryogen-
esis.within.the.living.and.developing.organisms.
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