Nanowire arrays combined with biological cells can serve as drug delivery systems as well as robust tools for advanced applications such as stimulation and sensing. In a paper published in the journal Advanced Materials Interfaces, the generation of neurons derived from induced pluripotent stem cells (iPSCs) on different nanowire arrays was demonstrated.
Study: Generation of neurons derived from human iPSCs in arrays of nanowires with variable lengths, pitches and diameters. Image credit: Jan Bruder/Shutterstock.com
Here, three different nanowire lengths, three array pitches, and two different nanowire diameters were combined for neuronal differentiation. Furthermore, the interactions between nanowires and cells range from fakir-like states to nanowire-encapsulated states based on the matrix characteristics.
After terminal differentiation of the cells on the nanowire arrays for eight to nine days, the cultures showed cells positive for neuronal markers in equal proportions. Furthermore, the developed neurons were similar in terms of functional action potential kinetics, specifying the equivalence of nanowire arrays for neuronal differentiation.
In addition, functionalized nanowire arrays can contribute to regenerative medicine and stem cell research to develop an understanding of mechanisms such as nanowire-based in vitro gene editing and intracellular delivery of biomolecules to regulate neural differentiation.
Technologies based on human iPSCs
Nanowire arrays can serve as cell culture substrates and play an important role in establishing new tools for cell interrogation and stimulation. Although previous reports mentioned the capabilities of nanowire arrays testing a variety of cell types, such as HEK293, GPE86, and HeLa cells, mesenchymal stem cells (MSCs), and primary neurons of rodents, the most sophisticated cells such as those derived from human iPSCs. may improve biomedical applications.
iPSCs are produced by co-expression of defined pluripotency-associated factors. Genuine iPSCs could develop into a whole embryo together with extraembryonic membranes. As the full pluripotency of iPSCs was previously demonstrated by several studies using the most stringent test, it is possible to derive truly pluripotent iPSCs from somatic cells. Because of these characteristics, iPSCs have numerous biomedical applications.
Technologies based on human iPSCs have greatly contributed to the field of research and preclinical applications. These technologies avoided the ethical and political controversies due to embryonic stem cells (ESCs) and helped generate major cell types, including brain organoids and blood-brain barrier models.
Passive nanowire arrays interact with the cell nucleus to measure the cell’s mechanical properties, stimulate the mechanotransduction machinery, or reorganize actin. The strong interactions between the substrate and the cell membrane help to improve the electrical recording and to stimulate the nanostructures equipped with microelectrode arrays.
The photoelectrochemical properties of nanowires, either in the form of arrays or in separate form (from the substrate), can be used to regulate neural or cardiac activities. In addition, nanowires can support intracellular delivery via endocytosis or via direct injection into the cell via electroporation in the case of a hollow nanowire.
Generation of neurons derived from human iPSCs
Although previous studies mentioned the possibility of generating neurons from human iPSC in nanowire arrays, the substrates used in these studies featured nanowires only 1 micrometer long, resulting in restricted deformational stress to the cells . Therefore, the effect of nanowire array geometry on neuronal differentiation remained unclear.
In the present study, we demonstrated the generation of human iPSC-derived neurons in nanowire arrays after 14–15 days of cell differentiation, with different combinations of three different lengths of nanowires, three different array steps, and two different diameters of the nanowire.
Varying interactions between the nanowire arrays and neurons resulted in substantial variation in the characteristics of the nanowire arrays. These cell-nanowire matrix interactions ranged from fakir-like encapsulation states to nanowires, in which the cell encapsulated the nanowires. While nanowire encapsulation was observed in short nanowires, large matrix pitches and thick diameters, fakir-like states were observed in long nanowires, small matrix pitches and thin diameters.
Nanowire arrays with 5-micrometer-long nanowires showed severe indentation and deformation of neurons, including their nucleus. The variable interaction of cells with nanowire arrays did not affect the neuronal marker-positive cells even after eight to nine days of cell differentiation on nanowire arrays.
Furthermore, the electrophysiological properties of the generated neurons determined the quality of neuronal differentiation in nanowire arrays. The culture substrates used for neuronal differentiation were equivalent, demonstrating the potential application of functionalized nanowire arrays for human iPSC-derived neurons.
conclusion
In conclusion, the present study demonstrated the generation of human iPSC-derived neurons in nanowire assays with multiple geometric specifications, such as different nanowire lengths, array pitches, and different nanowire diameters within 14–15 days of cultivation
Neuronal differentiation showed similarity to the flat control in terms of its electrophysiological properties and neuronal markers. Despite the topographical challenges, the equivalence in neuronal differentiation may aid future applications of the nanowire array by allowing tuning of its physical characteristics.
The results demonstrated the possibility of combining nanowire arrays with human iPSC-derived neurons that include the compilation of geometric features to facilitate various potential applications. Therefore, nanowire arrays are expected to contribute to regenerative medicine and stem cell research by improving cell interrogation and differentiation.
reference
Harberts, J., Siegmund, M., Hedrich, C., Kim, W., Fontcuberta i, A., Zierold, R., Blick, RH (2022) Generation of human iPSC-derived neurons in nanowire arrays with variable lengths, pitches and diameters. Adv. Mater. interfaceshttps://onlinelibrary.wiley.com/doi/10.1002/admi.202200806
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