Development and assessment of drug-eluting and anisotropic silk fibroin scaffolds for applications in peripheral nerve regeneration.
Nectow, Alexander.
2011
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Abstract:
Currently, there is no satisfactory treatment for peripheral nerve injury. Despite the
plethora of research conducted in this field, there is still no clinically available
nerve guidance conduit, which has surpassed the efficacy of the field's gold standard,
the autologous nerve graft. The autologous nerve graft, however, is plagued with a
variety of clinical complications, such as ... read moredonor site morbidity, limited availability,
nerve site mismatch, and the formation of neuromas. Thus, the development of a nerve
guidance conduit (NGC), which could match the effectiveness of the autologous nerve
graft, would be beneficial to the field of peripheral nerve surgery. Design strategies
have recently included the development of biopolymers and synthetic polymers as primary
scaffolds with tailored mechanical and physical properties, luminal "fillers" such as
laminin and fibronectin as secondary internal scaffolds, surface micropatterning, and
controlled release of neurotrophic factors. Peripheral nerve regeneration is a complex
process. Recent research has suggested that a combination of the above strategies will
yield successful treatments for peripheral nerve injury. To encourage directional
neurite outgrowth in vitro, anisotropic silk fibroin films of varying dimensions were
created and screened for optimized alignment, using the P19 cell line. After determining
the optimal micropattern dimensions, the silk fibroin films were then seeded with
neuronally differentiated PC-12 cells and assessed for cellular alignment in an
automated process. Cellular alignment is traditionally assessed using manually drawn
vectors connecting the neurite's end to the source on the soma. We wanted to develop an
automated process, which would assess the orientation of the neuron soma, which has
eccentricity in the direction of neurite outgrowth. In order to objectively assess PC-12
cellular alignment on the silk films, the Gauss-Newton algorithm was used to solve a
nonlinear least squares problem, which approximates the neuron's soma and the proximal
portions of the neurites as an ellipse. We found that this algorithm could accurately
assess cellular alignment in the earlier stages of differentiation for the PC-12 cell
line. After developing anisotropic films for nerve regeneration applications, we were
interested in controlled drug release for optimized peripheral nerve response. In vitro
bioassays investigated the efficacy of different release profiles of glial cell
line-derived neurotrophic factor (GDNF). We found that this neurotrophic factor can have
long-term, controlled release profiles and that the neurotrophic factors retain their
bioactivity throughout this process. The goal of peripheral nerve repair is to promote
the robust regenerative response of the proximal nerve cable, so that it may eventually
grow through its distal end, and recover functionality through synapsing with its
original output. Nerve regeneration is a complex process that requires the presence of
numerous factors, signaling cues, and design parameters to be successful. The above
developments are a step forward in the development of a comprehensive nerve guidance
conduit, which could provide an alternative solution to the autologous nerve
graft.
Thesis (M.S.)--Tufts University, 2011.
Submitted to the Dept. of Biomedical Engineering.
Advisor: David Kaplan.
Committee: Misha Kilmer, and Lauren Black.
Keywords: Biomedical Engineering, and Neurosciences.read less - ID:
- 70795m28g
- Component ID:
- tufts:20949
- To Cite:
- TARC Citation Guide EndNote
