Biomedical Engineering Reference
In-Depth Information
Coaxial electrospinning has also been investigated as a method of growth factor
delivery. In this method, two solutions are pumped through concentric needles to
form fibers containing an outer shell and inner core of different components. Placing
the solution containing the growth factor on the inside of the fiber reduces the
potential for denaturation by the organic solvent used to dissolve the outer polymer.
One study compared the release of bFGF from electrospun fibers that were prepared
by direct blending the bFGF into the polymer solution and by coaxial electrospinning
with bFGF in the core of the fiber.
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Both methods resulted in increased attachment,
proliferation, and differentiation of seeded bone marrow stem cells compared with
cells on fibers without bFGF. However, coaxial electrospinning resulted in a slower
release profile of bFGF compared with the blended method. Another study showed
that the protein release rate from a coaxial electrospun fiber could be increased by
increasing the feed rate of the core solution or by adding a polymer with a faster rate
of degradation (i.e., PEG) to the outer shell solution.
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The ability to tailor both the
mechanical and degradation properties of the scaffold as well as control the release
rate of growth factors from the scaffold makes this an attractive method for use in
future tissue engineering studies.
1.5 CONCLUSIONS
The ultimate goal in regenerative medicine and tissue engineering is to develop
technologies to repair or replace tissues without the complication of chronic immuno-
suppression and dependence on organ donors. The key to success is understanding of
how native tissues function and applying this information to establish the proper
combination of cellular, structural, and chemical components that will allow for
functional tissue development. Although perfect mimicry of the complex tissue
structure found in nature is unlikely to be reached soon, it is critically important to
gain a fuller understanding of how cells receive the signals needed to achieve the
appropriate phenotype and to form functional tissues once implanted in vivo.Itis
increasingly apparent that such investigations will need to transcend the tissue, or even
the cellular level, and take into consideration nanoscale phenomena that control
interactions between cells, scaffolds and bioactive substances. Significant advances
have beenmade both in deciphering the biology behind cell-matrix interactions aswell
as generating artificial ECM and controlling stem cell fate in the laboratory; however,
significant improvements remain necessary to make regeneration of tissues a wide-
spread clinical option. This chapter provides an abbreviated overview of the exciting
developments and conceptual and practical challenges in cell-nanomaterial biology
and engineering that is explored in depth in the chapters of this topic.
ACKNOWLEDGMENTS
Supported in part by NIH T32 HL076124 Cardiovascular Bioengineering Training
Program (ACB) and the Commonwealth of Pennsylvania Department of Health.
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