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<p>Regenerative medicine holds the promise of providing relief for people suffering
from diseases where treatment has been unattainable. The research is advancing rapidly;
however, there are still many hurdles to overcome before the therapeutic potential
of regenerative medicine and cell therapy can be realized. Low in frequency in all
tissues, stem cell number is often a limiting factor. Approaches that can control
the proliferation and direct the differentiation of stem cells would significantly
impact the field. Developing an adequate environment that mimics in vivo conditions
is an intensively studied topic for this purpose. Collaboratively, researchers have
come close to incorporating nearly all biological cues representative of the human
body. Arguably the most overlooked aspect is the influence of electrical stimulation.
In this dissertation, we examined polyvinylidene fluoride (PVDF) as a new biomaterial
and developed a 3D scaffold capable of providing mechanical and electrical stimuli
to cells in vitro. </p><p>The fabrication of a 3D scaffold was performed using electrospinning.
To obtain highly aligned fibers and scaffolds with controlled porosity, the set-up
was modified by incorporating an auxiliary electrode to focus the electric field.
Highly aligned fibers with diameters ranging from 500 nm to 15 µm were fabricated
from colorless polyimide (CP2) and polyglycolic acid (PGA) and used to construct multilayer
scaffolds. This experimental set-up was used to electrospin α-phase PVDF into
the polar β-phase. We demonstrated the transition to the β-phase by examining
the crystalline structure using x-ray diffraction (XRD), differential scanning calorimetry
(DSC), fourier transform infrared spectroscopy (FTIR) and polarized light optical
microscopy (PLOM). We confirmed these results by observing a polarization peak at
80°C using the thermally stimulated current (TSC) method. Our results proved the
electrospinning process used in our investigation poled the PVDF polymer in situ.
</p><p>TThe influence of architecture and topographical cues was examined on 3D scaffolds
and films of CP2 polyimide and PVDF. Culture of human mesenchymal stem cells (hMSCs)
for 7 and 14 days demonstrated a significant difference in gene expression. The fibers
upregulated the neuronal marker microtubule associated protein (MAP2), while downregulation
of this protein was observed on films. Gap junction formation was observed by the
expression of connexin-43 after 7 days on PVDF films attributed to its inherent pyroelectric
properties. Connexin-43 expression on fibers showed cell-cell contact across the
fibers indicating good communication in our 3D scaffold. </p><p>A scaffold platform
was designed using PVDF fibers that allowed us to apply electrical stimulation to
the cells through the fibers. The electrically stimulated PVDF fibers resulted in
enhanced proliferation compared to TCPS as evidenced by a 10% increase in the uptake
of EdU. Protein expression revealed upregulation of neuronal marker MAP2. Our findings
indicate this new platform capable of delivering mechanical, electrical, topographical
and biochemical stimuli during in vitro culture holds promise for the advancement
of stem cell differentiation and tissue engineering.</p>
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