Alginate-based hydrogel promotes neuronal survival and axon outgrowth of neuron-like cells

Abstract

Alginate is a natural polymer preferred for biotechnological applications due to its properties, such as biocompatibility, biodegradability, and low toxicity. However, neurons do not possess surface molecules interacting with alginate; therefore, alginate-based materials have limitations for neurodegenerative applications. Thus, increasing neuronal survival and promoting axonal outgrowth in the alginate-based hydrogels are the primary purposes of this study. We also aim to study the performance of alginate extracted from bioresources to that of commercial alginate. Cell-embedded alginate-based hydrogels were formed with CaCl2 and were either mixed with collagen type I or supplemented with differentiation protocols such as the addition of growth factors NGF or FGF, as well as serum withdrawal and retinoic acid (RA). Cells were observed by fluorescence imaging with acridine orange and propidium iodide, and upon dissolving the hydrogel with EDTA, cells were counted with trypan blue staining. In this study, both commercial alginate as well as alginate extracted from seaweed were compared for their performance and were found to be comparable. We determined that the addition of collagen to the alginate hydrogel increased neuronal survival but not axon outgrowth. NSC-34 cell differentiation with NGF and FGF was successful in both commercial and extracted alginate, with both growth factors increasing neural survival as well as axonal outgrowth, in spite of the clustering of cells immediately after treatment. However, the SH-SY5Y differentiation protocol using serum withdrawal and RA treatment did not yield good results. Both extracted and commercial alginates showed comparable performance in terms of neuronal survival in our study, which was further increased upon collagen addition. We also showed that NGF and FGF differentiation protocol in alginate hydrogels resulted in successful axon outgrowth in NSC-34 cells.

Keywords

• Alginate
• Nerve growth factor (NGF)
• Fibroblast growth factor (FGF)
• hydrogel
• NSC-34 motor-like neuron cell line
• SH-SY5Y human neuroblastoma cell line

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