What is it about?
Engineered nanomaterials are often used in tissue engineering applications to influence and manipulate the behavior of cells. Recently, a number of tungsten-silicon oxide nanocomposite devices containing equal width (symmetric) tungsten and silicon oxide parallel line comb structures were developed and used by our group. The devices induced over 90% of seeded cells (Vero) to align within ±20° of the axes of 10 µm wide tungsten lines. Furthermore, a mathematical model was successfully developed to predict this alignment behavior and forecast the minimum width of isolated tungsten lines required to induce such behavior. However, the mechanism by which the widths of the symmetrical tungsten and silicon oxide lines induce the alignment behavior is still unknown. Furthermore, the model was never tested on more complex asymmetrical structures. Herewith, experiments were conducted with mammalian cells on complex asymmetrical structures with unequal tungsten and silicon oxide line widths. Results showed that the model could be extended to more complex pattern structures. In addition, cell morphology on the patterned structures reset during cell division because of mitotic rounding, which reduced the population of cells that elongated and aligned on the tungsten lines. Ultimately, we concluded that it was impossible to achieve a 100% alignment with cells having unsynchronized cell cycles because cell rounding during mitosis took precedence over cell alignment; in other words, internal chemical cues had a stronger role in cell morphology than external cues.
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Why is it important?
it is our hypothesis that even under the most favorable experimental conditions, the reshaping of cells during mitosis is one of the reasons a small population of cells remains misaligned. This is thought to be the direct result of cells maintaining a near spherical shape during the cell division process. Hence, it is statistically unlikely, at any time during the experiment, to have all cells aligned in the desired direction, if the cells are incubated for longer than the cell doubling time and have not had their cell cycle synchronized. Therefore, the third objective of this work is to demonstrate that mitotic rounding can be a limiting factor for cell manipulation on engineered surfaces. Vero cells are from an industrially relevant adherent cell line that require surfaces to grow. They are commonly used in virus infection [22] studies and were chosen for their ease of culture. It is also believed that, although they are transfectable [23], the cell line, and its transfectability, can be enhanced by manipulating the cells’ morphologies.
Perspectives
The abilities of the newly developed W-CMP asymmetrical line nanocomposite device to manipulate the alignment behavior of cells were studied. Results demonstrated that the preferential alignment and adhesion behaviors of Vero cells were silicon oxide line width dependent. Moving forward, this will be an important design parameter to consider when designing new tungsten and silicon oxide based nanocomposites. Designing such devices will be easier given that a simple model was shown to predict the propensity of cells to orient themselves based on line width and overall cell size. It should be noted, however, that prior to this study, our hypothesis was that cell division interfered with complete population alignment. Fluorescence confocal micrographs showed that mitotic rounding during cell division reset the cell morphology to an isotropic shape. This provided a possible explanation for why it was difficult to manipulate the entire population of cells to align and elongate in a preferential direction even under the most ideal pattern design and incubation parameters and conditions. Future studies should now be focused on utilizing oriented cells for a specific purpose. In the case of Vero cells, the transfectability of the cells will be further probed. Concomitantly, fully synchronized cultures will be examined to ensure a uniform effect on all cells in the culture.
PhD Hassan I. Moussa
Conestoga College Institute of Technology and Advanced Learning
Read the Original
This page is a summary of: Limitation in Controlling the Morphology of Mammalian Vero Cells Induced by Cell Division on Asymmetric Tungsten-Silicon Oxide Nanocomposite, Materials, January 2020, MDPI AG,
DOI: 10.3390/ma13020335.
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