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Maximizing cell growth per passage using polystyrene fibers
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Maximizing cell growth per passage using polystyrene fibers

Nazmiye Celik
Master of Science (M.S.), Drexel University
Sep 2017
DOI:
https://doi.org/10.17918/etd-7572
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Abstract

Polystyrene Biomedical Engineering Cell Culture
Tissue-engineering strategies often demand a large number of stem cells and cells passaging, which is usually achieved cell expansion on a two-dimensional (2D) substrate, such as a Petri dish or culturing flask. Stem cells on these 2D systems become confluence in about one or two weeks, reaching 3 to 5-fold maximum proliferation, and must be trypsinized, detached and re-plated to continue cell expansions. However, trypsinization exposes stem cells to biochemical and biophysical stresses that are known to accelerate cell senescence, phenotype changes, and the loss of stemness and multipotentiality. In this study, I hypothesized that a cell-expanding strategy that maximize the folds of cell proliferation before trypsinization may promote the phenotype stability of stem cells. A three-dimensional (3D) cell-expansion system using ribbon-shapes polystyrene was developed, which is the same material used for making culture flasks. In contrast to traditional cell expansion, these micro ribbons (500 micron wide and 50 microns thick) provide a gradually increasable surface area per weight to support high cell proliferation, enabling a maximum cell number per passage that is higher than the traditional system (by more than 10 folds). Cells reaching confluence were re-suspended by trypsin following the similar protocols for the 2D cell expansion. Human mesenchymal stem cells (hMSCs) were used as the model cell type to compare the differences between the results of my 3D cell expansion and that of the 2D cell expansion. These results include the MSC proliferation rate on, change of gene expression post passaging on the both 3D ribbon-based and 2D traditional groups. In addition, the capacity MSCs expanded by traditional 2D method to differentiate into bone and fat-like cells phenotypes was evaluated with increasing re-plating and passaging the cell culture. The result of my study showed that the PS-ribbons provide a 3D environment for cell expansion with enabling continual cell proliferation, in the absence of the traditional cycles of trypsinization, cell detachment, and re-plating cycles. With this study, the efficacy of using PS ribbons was evaluated in terms of the performance of cell proliferation rates, and the maintenance of MSC phenotype.

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