Biomedical Engineering Reference
In-Depth Information
canine osteoblast cells, and the scaffolds with rhBMP-2 were shown
to induce higher osteocalcin expression than control groups, but
even scaffolds without rhBMP-2 were shown to sustain osteogenic
expression, as shown by osteocalcin expression and mineral con-
tent. This demonstrated the feasibility of using FDM-fabricated
PCL scaffolds as a platform for cell-based tissue engineering and a
delivery system for rh-BMP-2. In this study rhBMP-2 was not incor-
porated into the scaffold during manufacture as the FDM process
involves high heat; rather rhBMP-2 was loaded directly on the scaf-
foldafterfabrication.Inaseparatestudydemonstratingthemechan-
ical properties of FDM-fabricated PCL scaffolds, honeycomb-shaped
scaffoldswithacompletelyinterconnectedporestructureweresub-
jected to compressive testing.
8
The scaffolds were shown to have
a yield strength of 2.3 MPa and a compressive stiffness of 29.4
MPa at physiological conditions. The mechanical properties were
showntochangebasedonthelay-downpatternofthescaffold.Scaf-
folds were seeded with human fibroblasts and osteoblast-like cells
to evaluate the e
cacy of using the scaffolds in cell-based tissue
engineering strategies. Immunohistochemistry analysis and confo-
cal microscopy revealed the cells had proliferated throughout the
scaffolds and deposited an extracellular matrix. This study demon-
stratedthatFDMcouldbeusedtodevelopatissueengineeringscaf-
fold suitable for cell seeding and that the scaffold had su
cient
mechanicalpropertiestoserveasabonetissueengineeringscaffold.
Like many other SFF techniques, FDM is limited by the materi-
alsthatcanbeused,asthepolymermustbemeltedandresolidified.
Because of the high heat associated with the polymer melting, bio-
molecules cannot be directly incorporated into the scaffold. FDM is
abletoachievehigherporositiesthanSLSand3DP,butasporesizeis
decreased it becomes technically di
cult to maintain high porosity.
Like SLS, FDM does not require the use of a binding agent or sol-
vent, which is advantageous in avoiding toxic contamination in the
scaffold. However, some scaffolds may require a secondary support
material, which could potentially be harmful to cells. Several cell
studieshavedemonstratedtheabilityofFDM-fabricatedscaffoldsto
support osteoblastic cell phenotype, verifying that FDM represents
a promising tool for the development of scaffolds with a controlled
architecture.
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