Electroconductive nanoscale topography for enhanced neuronal differentiation and electrophysiological maturation of human neural stem cells

Abstract

Biophysical cues, such as topography, and electrical cues can provide external stimulation for the promotion of stem cell neurogenesis. Here, we demonstrate an electroconductive surface nanotopography for enhancing neuronal differentiation and the functional maturation of human neural stem cells (hNSCs). The electroconductive nanopatterned substrates were prepared by depositing a thin layer of titanium (Ti) with nanograting topographies (150 to 300 nm groove/ridge, the thickness of the groove - 150 μm) onto polymer surfaces. The Ti-coated nanopatterned substrate (TNS) induced cellular alignment along the groove pattern via contact guidance and promoted focal adhesion and cytoskeletal reorganization, which ultimately led to enhanced neuronal differentiation and maturation of hNSCs as indicated by significantly elevated neurite extension and the upregulated expression of the neuronal markers Tuj1 and NeuN compared with the Ti-coated flat substrate (TFS) and the nanopatterned substrate (NS) without Ti coating. Mechanosensitive cellular events, such as β1-integrin binding/clustering and myosin-actin interaction, and the Rho-associated protein kinase (ROCK) and mitogen-activated protein kinase/extracellular signal regulated kinase (MEK-ERK) pathways, were found to be associated with enhanced focal adhesion and neuronal differentiation of hNSCs by the TNS. Among the neuronal subtypes, differentiation into dopaminergic and glutamatergic neurons was promoted on the TNS. Importantly, the TNS increased the induction rate of neuron-like cells exhibiting electrophysiological properties from hNSCs. Finally, the application of pulsed electrical stimulation to the TNS further enhanced neuronal differentiation of hNSCs due probably to calcium channel activation, indicating a combined effect of topographical and electrical cues on stem cell neurogenesis, which postulates the novelty of our current study. The present work suggests that an electroconductive nanopatterned substrate can serve as an effective culture platform for deriving highly mature, functional neuronal lineage cells from stem cells.

Nano-Architectural Approaches for Improved Intracortical Interface Technologies

“…Cells are signaled to release expression factors and non-soluble ECM molecules that are necessary for cell adhesion, proliferation, morphology, and phenotypic changes ( Selvakumaran et al, 2008 ; Jang et al, 2010 ; Yoo et al, 2015 ; Schulte et al, 2016a ; Yang et al, 2017 ). Likewise, a nano-architecture substrate will allow cells to sense structural cues, which triggers a similar cellular response observed when cells are in their natural environment surrounded by the ECM ( Selvakumaran et al, 2008 ; Yoo et al, 2015 ; Schulte et al, 2016a ; Yang et al, 2017 ). The nano-architecture surfaces provide cues to initiate the production of ECM molecules necessary for initial cell attachment to surfaces ( Cui et al, 2018 ).…”

“…NSC on the nano-architectures exhibited higher ratio of differentiation into dopaminergic and glutamatergic neurons compared to NSC cultured on flat substrates. Scale bar is 50 microns ( Yang et al, 2017 ). Reproduced in part from Yang et al (2017) with permission of The Royal Society of Chemistry.…”

Piezoelectric Nanotopography Induced Neuron‐Like Differentiation of Stem Cells

“…Previous studies have confirmed that stripe arrays with ridge/groove in the range of 200 to 1000 nm can provide assistance for the neural differentiation of stem cells . To clarify the structure effect of the stripe assays, two kinds of PVDF films with distinct stripe arrays and identically structured polyvinyl chloride (PVC) films are replicated from homostructural silicon molds: one with a repetition period of 400 nm (ridge, groove, and height were all 200 nm, denoted as PVDF‐200), whereas the other has a repetition period of 1000 nm (ridge, groove, and height were all 500 nm, denoted as PVDF‐500).…”

Engraving the Surface of Electrospun Microfibers with Nanoscale Grooves Promotes the Outgrowth of Neurites and the Migration of Schwann Cells

“…[29] It was shown that the nanostructures with asmaller dimension (e.g., grooves with width at 300 nm versus 600, 900, 1200, and 1500 nm) were found to be more effective in enhancing focal adhesion of neural stem cells for their differentiation toward neurons.Although these flat and often rigid substrates are convenient for in vitro studies,t hey cannot be adapted for the fabrication of NGCs. [29][30][31] In this regard, electrospun fibers offer an immediate advantage because the mat of fibers can be easily rolled up to obtain NGCs with tunable diameters to match the sizes of various types of nerves.B esides,t he groove-engraved microfibers developed in this work can be made with controlled biodegradability by varying the formulation of the core solution. Thef ibers can also serve as carriers for the encapsulation and controlled release of proteins and/or growth factors.…”