Article pubs.acs.org/Langmuir
Successful Differentiation of Neural Stem/Progenitor Cells Cultured on Electrically Adjustable Indium Tin Oxide (ITO) Surface ̂
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Kin Fong Lei,*,†,‡,∥ I-Chi Lee,*,§,∥ Yung-Chiang Liu,§ and Yu-Chieh Wu§ †
Graduate Institute of Medical Mechatronics, Chang Gung University, Taoyuan, Taiwan Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan § Graduate Institute of Biochemical and Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan ‡
S Supporting Information *
ABSTRACT: In order to control differentiation of neural cells and guide the developed neurites to targets, polyelectrolyte multilayer (PEM) films were used because of their capability of modulation of electrical charged characteristics, thickness, and stiffness. In this work, we suggested that indium tin oxide (ITO) is an alternative surface to achieve the above-mentioned objectives. A microfluidic system with four culture chambers was developed and each chamber consisted of parallel ITO surfaces for the application of adjustable electrical field. Neural stem/progenitor cells (NSPCs) were respectively cultured on the ITO surfaces with and without PEM film, constructed by alternate adsorption of poly(L-lysine) (PLL) and poly(L-glutamic acid) (PLGA). Analyses of cell morphology, cytotoxicity, process outgrowth, differentiated cell types, and neuron functionality were compared between both surfaces. In this study, NSPCs successfully differentiated on ITO surface with electrical stimulation. The optimal electrical potential was found to be 80 mV that could stimulate the longest process, i.e., >300 μm, after 3 days culture. Cell differentiation, process development, and functionality of differentiated neuron on ITO surface were shown to be strongly controlled by the electrical stimulation that can be simply adjusted by external equipment. The electrically adjustable cell differentiation reported here could potentially be applied to neurochip for the study of neural signal transmission in a wellconstructed network.
1. INTRODUCTION With mature development of microfluidic technology, cells can be manipulated and cultured in a closed volume environment for the study of cellular behavior.1,2 Moreover, an electronic circuit was demonstrated to be integrated into the microfluidic chip for electrical stimulation and recording of cellular responses.3−5 The opportunity for the combination of microelectronics and neural cells has attracted a great deal of attention because it opens up an avenue for research on brain chips and neurocomputers.6 However, the interface between electronic circuits and synaptically connected neurons is a major challenge in the assembly and manufacture of the hybrid circuits. To promote the adhesion of neural cells on the circuit, protein and peptide molecules were used as the coating materials, such as fibronectin protein7 and Arg-Gly-Asp (RGD) peptide.8 Better cell attachment was demonstrated on these immobilized surfaces. Moreover, development of new coating materials was recently focused to improve cyto-compatibility, i.e., environmental suitability for cell culture, through extracellular matrix (ECM) components and microstructures. Layer-by-layer assembly of polyelectrolyte multilayer (PEM) films has been demonstrated for improvement of the cytocompatibility of neural cells.9−14 Self-assembled polycations and polyanions are alternatively deposited on a solid surface to form a PEM film. This method provides adjustable film properties in © 2014 American Chemical Society
terms of thickness, morphology, and internal molecular structure.15,16 For example, the surface morphology of a hyaluronic acid (HA)-based PEM film (bilayer number
