Silk scaffolds for neural tissue engineering.
Hopkins, Amy.
2013
-
Abstract: There is a critical need for therapies that promote neural
regeneration and target disease mechanisms of the nervous system. Neural tissue engineering
(TE) is in the early stages of development with research focusing on several aspects of
therapeutics including peripheral nerve repair, image processing analysis techniques, and
in vitro tissue systems. TE functional neural systems pre... read moresent unique challenges including
low tissue stiffness, high cell density, and complex neural network functions still being
elucidated in vivo. Silk biomaterials are attractive candidates for TE applications due to
their biocompatibility, aqueous-based processing, and robust and tunable mechanical and
degradation properties. The present work evaluated two silk scaffold platforms for neural
TE applications: (1) silk hydrogels, and (2) silk sponges. Mechanical stiffness and
biochemical functionalization of silk hydrogels were examined for promotion of neurite
extension for peripheral nerve guidance. One to 8% silk hydrogels exhibited low stiffness
of 4-33kPa as measured by atomic force microscopy. The structural integrity of the silk
gels was maintained throughout cell culture whereas fibrin and collagen gels decreased in
mass over time. Neurite extension was greatest on 2 and 4% silk hydrogels as compared to
softer or stiffer gels and gels loaded with neurotrophin-3 exhibited low release of <5%
and remained bioactive over 2 weeks. Functionalization of silk hydrogels with fibronectin
and laminin led to observations of differences in axonal bundling. Due to the lack of
quantitative image processing methods for analysis of fasciculation events, silk hydrogels
were employed for development of a semi-automated neurite directional distribution analysis
(NDDA) program, which quantifies fasciculation based on tortuosity of neurite extension.
Finally, a compartmentalized silk sponge scaffold with arrays of hollow channels was
characterized for development of 3D neuron cell culture systems. The silk sponge scaffold
allowed for localized, long-term co-cultures of vascular and neuronal cells and resembled
the 3D architecture of the neurovascular unit (NVU). The 3D NVU culture system has
potential for supplementing 2D cultures and animal models for CNS therapeutic development.
Collectively, this work exemplifies several neural TE applications with silk biomaterial
scaffolds offering promising in vitro systems for understanding nervous system mechanisms
and therapeutic development.
Thesis (Ph.D.)--Tufts University, 2013.
Submitted to the Dept. of Biomedical Engineering.
Advisor: David Kaplan.
Committee: Fiorenzo Omenetto, Barry Trimmer, Michael Whalen, and Cristian Staii.
Keyword: Biomedical engineering.read less - ID:
- js956s618
- Component ID:
- tufts:21966
- To Cite:
- DCA Citation Guide EndNote
