Biomedical Engineering Reference
In-Depth Information
Fibers
Adhesive proteins
Proteoglycans
Figure 8.1
(See companion CD for color igure.)
.The.topography.of.the.ECM.is.characterized.by.various.features—many.
falling.within.nanoscale.proportions..The.intertwined.ibers.act.as.structural.supports,.while.adhesive.proteins.
facilitate.interaction.between.cells.and.matrix..Proteoglycans.occupy.the.interstitial.voids.to.protect.the.ECM.
from.external.stresses.and.attract.growth.factors.
laminins..Collagens.primarily.provide.support.for.the.cells.residing.in.different.tissues..
Elastins.complement.the.general.stiffness.of.collagens.by.providing.some.lexibility..Unlike.
the. aforementioned. two. structural. components,. laminins—small. adhesive. proteins—
work. to. attract. integrins,. which. are. responsible. for. facilitating. an. array. of. cell-cell. and.
cell-matrix.interactions..The.interstitial.matrix.ills.the.voids.of.the.basement.membrane's.
ibrous.network..It.contains.a.number.of.proteoglycans—heparin.sulfate.and.hyaluronic.
acid,. for. example—that. safeguard. the. ECM. from. stresses. imposed. on. it. and. promote.
deposition.of.growth.factors.(Dvir.et.al..2011).
8.1.2 Biomimetic Materials
Formerly. perceived. as. merely. a. structural. scaffold. for. the. body's. tissues. and. organs,.
the.ECM.has.emerged.as.an.indispensible.guide.for.cell.morphogenesis,.proliferation,.
differentiation,.adhesion,.and.migration.(Tsang.et.al..2010)..An.avenue.of.great.interest.
in. tissue. engineering. involves. designing. biomaterials. that. can. function. in. the. same,.
or. at. least,. in. a. highly. similar. capacity. as. the. natural. ECM.. Much. effort. has. initially.
focused. on. the. macroscopic. microenvironment. and. how. to. better. replicate. it.. But.
the. eventual. need. to. pay. attention. to. the. nanoscale. becomes. apparent,. as. various.
components. of. the. ECM. function. at. that. level.. For. example,. synthetic. nanoibers.
(50-500.nm). have. been. generated. to. mimic. the. ECM's. naturally. occurring. collagen.
I. ibers. (Smith. and. Ma. 2011).. One. of. the. most. direct. approaches. to. manipulate. cell.
behavior. is. to. vary. a. substrate. to. match. the. natural. cell-substrate. interactions.. Such.
biomimetic. surfaces. are. produced. from. a. repertoire. of. fabrication. techniques.. Early.
attempts.entailed.crude.methods,.such.as.etching,.sandblasting,.and.particle.coating..
The.progression.into.more.advanced.terrain.was.marked.by.approaches.that.included.
electrospinning,.phase.separation,.polymer.demixing,.and.self-assembly..Additionally,.
surfaces. were. further. augmented. with. ECM. macromolecules. to. enhance. bioactivity.
(von. der. Mark. et. al.. 2010).. More. recent. lithographic. techniques. (colloidal,. electron.
beam,. nanoimprint,. etc.),. originally. invented. for. the. microelectronic. industry,. have.
the. capability. to. produce. nanopatterns. at. very. high. resolution. and. great. complexity..
Adopted.for.biomedical.applications,.these.advanced.fabrication.techniques.will.help.
understand.how.cells.interact.with.the.natural.ECM.and.inspire.the.next.generation.of.
biomaterials.and.implant.design.
