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Creators/Authors contains: "Eftekhari, Behnaz Sadat"

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  1. Abstract

    Electrical stimulation (ES) within a conductive scaffold is potentially beneficial in encouraging the differentiation of stem cells toward a neuronal phenotype. To improve stem cell‐based regenerative therapies, it is essential to use electroconductive scaffolds with appropriate stiffnesses to regulate the amount and location of ES delivery. Herein, biodegradable electroconductive substrates with different stiffnesses are fabricated from chitosan‐grafted‐polyaniline (CS‐g‐PANI) copolymers. Human mesenchymal stem cells (hMSCs) cultured on soft conductive scaffolds show a morphological change with significant filopodial elongation after electrically stimulated culture along with upregulation of neuronal markers and downregulation of glial markers. Compared to stiff conductive scaffolds and non‐conductive CS scaffolds, soft conductive CS‐g‐PANI scaffolds promote increased expression of microtubule‐associated protein 2 (MAP2) and neurofilament heavy chain (NF‐H) after application of ES. At the same time, there is a decrease in the expression of the glial markers glial fibrillary acidic protein (GFAP) and vimentin after ES. Furthermore, the elevation of intracellular calcium [Ca2+] during spontaneous, cell‐generated Ca2+transients further suggests that electric field stimulation of hMSCs cultured on conductive substrates can promote a neural‐like phenotype. The findings suggest that the combination of the soft conductive CS‐g‐PANI substrate and ES is a promising new tool for enhancing neuronal tissue engineering outcomes.

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  2. Abstract

    Incomplete regeneration and restoration of function in damaged nerves is a major clinical challenge. In this regard, stem cells hold much promise in nerve tissue engineering, with advantages such as prevention of scar‐tissue ingrowth and guidance of axonal regrowth. Engineering 3D and patterned microenvironments using biomaterials with chemical and mechanical characteristics close to those of normal nervous tissue has enabled new approaches for guided differentiation of various stem cells toward neural cells and possible treatment of neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's diseases. Differentiation of stem cells in a neurogenic lineage is largely affected by signals from the surrounding microenvironment (niche). The stem cell niche refers to a specific microenvironment around the stem cells, which provides specific biochemical (soluble factors) and biophysical signals (topography, electrical, and mechanical). This specified niche regulates the stem cells' behavior and fate. While the role of chemical cues in neural differentiation is well appreciated, recently, the cues presented by the physical microenvironment are increasingly documented to be important regulators of nerve cell differentiation. The single and synergistic effects of surface topography and electrical signals on neural differentiation of stem cells are reviewed.

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