Browsing by Author "Zhao, Yiping"

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    Effects of Topography on the Functional Development of Human Neural Progenitor Cells
    (Biotechnology and bioengineering, 2010) Wu, Ze-Zhi; Kisaalita, William S.; Wang, Lina; Zachman, Angela L.; Zhao, Yiping; Hasneen, Kowser; Machacek, Dave; Stice, Steven L.
    We have fabricated a topographical substrate with a packed polystyrene bead array for the development of cell‐based assay systems targeting voltage‐gated calcium channels (VGCCs). Human neural progenitor cells (H945RB.3) cultured on both flat and topographical substrates were analyzed in terms of morphological spreading, neuronal commitment, resting membrane potential (Vm) establishment and VGCC function development. We found, by SEM imaging, that arrayed substrates, formed with both sub‐micrometer (of 0.51 µm in mean diameter) and micrometer (of 1.98 µm in mean diameter) beads, were capable of promoting the spreading of the progenitor cells as compared with the flat polystyrene surfaces. With the micrometer beads, it was found that arrayed substrates facilitated the neural progenitor cells' maintenance of less negative Vm values upon differentiation with bFGF starvation, which favored predominant neuronal commitment. Almost all the progenitor cells were responsive to 50 mM K+ depolarization with an increase in [Ca2+]i either before or upon differentiation, suggesting the expression of functional VGCCs. Compared to the flat polystyrene surfaces, microbead arrayed substrates facilitated the development of higher VGCC responsiveness by the progenitor cells upon differentiation. The enhancement of both VGCC responsiveness and cell spreading by arrays of micrometer beads was most significant on day 14 into differentiation, which was the latest time point of measurement in this study. This study thus rationalized the possibility for future substrate topography engineering to manipulate ion channel function and to meet the challenge of low VGCC responsiveness found in early drug discovery. Biotechnol. Bioeng. 2010;106: 649–659. © 2010 Wiley Periodicals, Inc.
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    Interfacing SH-SY5Y human neuroblastoma cells with SU-8 microstructures
    (Colloids and Surfaces B: Biointerfaces, 2006) Wu, Ze-Zhi; Zhao, Yiping; Kisaalita, William S.
    Microwell structures were fabricated using SU-8 photoresist for engineering a quasi-three-dimensional (quasi-3D) microenvironment for cultured neuronal cells. SH-SY5Y human neuroblastoma cells were successfully integrated into microwells of a nominal diameter of 100 μm, with or without 10-μm wide microchannels connecting neighboring microwells, in an aspect ratio (ratio of structure depth over width) of approximately 1. With the help of polyethylene glycol stamping and laminin coating, a neuronal-like network was achieved by integrating populations of SH-SY5Y cells with a microwell network pattern. Resting membrane potential establishment was evaluated with confocal microscopy and the potentiometric fluorescent dye tetramethylrhodamine methyl ester. It was found that the intra/extracellular fluorescent intensity ratio (R) was 2.4 ± 1.4 [n (number of cells measured) = 112] for SH-SY5Y cells on flat SU-8 substrates on day 5 into differentiation, which was not significantly different from the ratio on day 13 into differentiation, 2.0 ± 1.8 (n = 104) (P > 0.05). For cells in the microwell network structures, R was 4.8 ± 4.7 (n = 51) and 3.9 ± 3.2 (n = 62) on days 5 and 13 into differentiation, respectively (P > 0.5). Cells within the network structures had higher R ratios than on flat substrates, for either day 5 or 13 into differentiation (P < 0.01). These results demonstrated that the well network structures, or topographically patterned substrates, were more suitable formats for promoting SH-SY5Y cell resting membrane potential establishment than flat substrates, suggesting the potential to control cellular function through substrate topography engineering.
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    Microstructured Topography Enhanced the Responsiveness of Voltage-gated Calcium Channels in H945RB.3 Human Neural Progenitor Cells
    (International Conference on Bioinformatics and Biomedical Engineering, 2009) Wu, Ze-Zhi; Kisaalita, William S.; Wang, Lina; Zhao, Yiping
    A topographical substrate with a packed polystyrene microbead (1.98 plusmn 0.20 mum in diameter) array was fabricated for the development of cell-based assay systems targeting voltage-gated calcium channels (VGCCs). We found that the microbead arrayed substrates enhanced the attachment and spreading of the cultured human neural progenitor cells (H945RB.3) as compared to the flat polystyrene surfaces. Microbead arrayed substrates also facilitated the development of higher VGCC responsiveness upon neuronal differentiation than flat substrates. The enhancement of both VGCC responsiveness and cell spreading were most significant until day 14 into differentiation.