Highly Aligned Poly(3,4-ethylene dioxythiophene) (PEDOT) Nano- and Microscale Fibers and Tubes.

This study reports a facile method for the fabrication of aligned Poly(3,4-ethylene dioxythiophene) (PEDOT) fibers and tubes based on electrospinning and oxidative chemical polymerization. Discrete PEDOT nano- and microfibers and nano- and microtubes are difficult to fabricate quickly and reproducibly. We employed poly(lactide-co-glycolide) (PLGA) polymers that were loaded with polymerizable 3,4-ethylene dioxythiophene (EDOT) monomer to create aligned nanofiber assemblies using a rotating glass mandrel during electrospinning. The EDOT monomer/PLGA polymer blends were then polymerized by exposure to an oxidative catalyst (FeCl3). PEDOT was polymerized by continuously dripping a FeCl3 solution onto the glass rod during electrospinning. The resulting PEDOT fibers were conductive, aligned and discrete. Fiber bundles could be easily produced in lengths of several centimeters. The PEDOT sheath/PLGA core fibers were immersed in chloroform to remove the PLGA and any residual EDOT resulting in hollow PEDOT tubes. This approach made it possible to easily generate large areas of aligned PEDOT fibers/tubes. The structure and properties of the aligned assemblies were measured using optical microscopy, electron microscopy, Raman spectroscopy, thermal gravimetric analysis, and DC conductivity measurements. We also demonstrated that the aligned PEDOT sheath/PLGA core fiber assemblies could be used in supporting and directing the extension of dorsal root ganglia (DRG) neurons in vitro.

Combining topographical and genetic cues to promote neuronal fate specification in stem cells.

There is little remedy for the devastating effects resulting from neuronal loss caused by neural injury or neurodegenerative disease. Reconstruction of damaged neural circuitry with stem cell-derived neurons is a promising approach to repair these defects, but controlling differentiation and guiding synaptic integration with existing neurons remain significant unmet challenges. Biomaterial surfaces can present nanoscale topographical cues that influence neuronal differentiation and process outgrowth. By combining these scaffolds with additional molecular biology strategies, synergistic control over cell fate can be achieved. Here, we review recent progress in promoting neuronal fate using techniques at the interface of biomaterial science and genetic engineering. New data demonstrates that combining nanofiber topography with an induced genetic program enhances neuritogenesis in a synergistic fashion. We propose combining patterned biomaterial surface cues with prescribed genetic programs to achieve neuronal cell fates with the desired sublineage specification, neurochemical profile, targeted integration, and electrophysiological properties.

Electrospun fibers and tissue engineering.

Electrospinning is an exciting technique attracting more and more attention as a potential solution to the current challenges in the field of tissue engineering. This technique can be used to produce fibrous scaffolds with excellent biocompatibility and biodegradability, as well as suitable micro-/nanostructure to induce desired cellular activities and to guide tissue regeneration. In order to develop electrospun fibrous scaffolds for these applications, different biocompatible materials including natural polymers, synthetic polymers and inorganic substances and preparations have been used to fabricate electrospun fibers with different structures and morphologies. This review briefly describes the development of the technique, focusing on several typically electrospun materials, surface modification of electrospun fibers, and current applications in tissue engineering.

Stages of neuronal morphological development in vitro--an automated assay.

Following plating in vitro, neurons pass through a series of morphological stages as they adhere and mature. These morphological stage transitions can be monitored as a function of time to evaluate the relative health and development of neuronal cultures under different conditions. While morphological development is usually quite obvious to the experienced eye, it can often be difficult to quantify in a meaningful way. Morphology quantification typically relies on manual image measurement and can therefore be tedious, time consuming and prone to human error. Here we report the successful development of an automated process using the commercially available image analysis program MetaMorph(®) to analyze the morphology and quantify the growth of embryonic spinal motor neurons in vitro. Our process relied on the Neurite Outgrowth and Cell Scoring modules included in MetaMorph(®) and on analyzing the exported data with an algorithm written in MATLAB(®). We first adopted a series of stages of motor neuron development in vitro. Neurons were classified into these stages directly from the available output of MetaMorph(®) using the algorithm written in MATLAB(®). We validated the results of the automated analysis against a manual analysis of the same images and found no statistically significant difference between the two methods. When properly configured, automated image analysis with MetaMorph(®) is a rapid and reliable alternative to manual measurement and has the potential to accelerate the research process.

The culture of primary motor and sensory neurons in defined media on electrospun poly-L-lactide nanofiber scaffolds.

Electrospinning is a technique for producing micro- to nano-scale fibers. Fibers can be electrospun with varying degrees of alignment, from highly aligned to completely random. In addition, fibers can be spun from a variety of materials, including biodegradable polymers such as poly-L-lactic acid (PLLA). These characteristics make electrospun fibers suitable for a variety of scaffolding applications in tissue engineering. Our focus is on the use of aligned electrospun fibers for nerve regeneration. We have previously shown that aligned electrospun PLLA fibers direct the outgrowth of both primary sensory and motor neurons in vitro. We maintain that the use of a primary cell culture system is essential when evaluating biomaterials to model real neurons found in vivo as closely as possible. Here, we describe techniques used in our laboratory to electrospin fibrous scaffolds and culture dorsal root ganglia explants, as well as dissociated sensory and motor neurons, on electrospun scaffolds. However, the electrospinning and/or culture techniques presented here are easily adapted for use in other applications.