Abstract
The topography of a biomaterial regulates cellular interactions and determine stem cell fate. A complete understanding of how topographical properties affect cell behavior will allow the rational design of material surfaces that elicit specified biological functions once placed in the body. To this end, we fabricate substrates with aligned or randomly organized fibrous nanostructured topographies. Culturing adipose-derived stem cells (ASCs), we explore the dynamic relationship between the alignment of topography, cell shape and cell differentiation to osteogenic and myogenic lineages. We show aligned topographies differentiate cells towards a satellite cell muscle progenitor state - a distinct cell myogenic lineage responsible for postnatal growth and repair of muscle. We analyze cell shape between the different topographies, using fluorescent time-lapse imaging over 21 days. In contrast to previous work, this allows the direct measurement of cell shape at a given time rather than defining the morphology of the underlying topography and neglecting cell shape. We report quantitative metrics of the time-based morphological behaviors of cell shape in response to differing topographies. This analysis offers insights into the relationship between topography, cell shape and cell differentiation. Cells differentiating towards a myogenic fate on aligned topographies adopt a characteristic elongated shape as well as the alignment of cells.
Highlights
The topography of a biomaterial regulates cellular interactions and determine stem cell fate
A deeper understanding of the relationship between these properties will allow for the rational design of material surfaces capable of directing cell shape and differentiation. To this end we explore the dynamic relationship between alignment of topography, cell shape and cell differentiation
This study demonstrates that an aligned topography does not upregulate osteogenesis[27,28]
Summary
Random and aligned topographies were fabricated by coating glass coverslips with carbon nanotubes (CNTs) from an aligned drawable forest[29] (Figure S1), where uncoated glass coverslips served as the flat topography. Osteogenic gene expression is not altered when ASCs were cultured on flat, random and aligned topographies at either 14 or 21 days. In agreement with the qRT-PCR results, neither flat, random or aligned topographies alter mineral deposition when compared to flat-osteo conditions at day 21. We directly measured cell shape over 21 days using fluorescent time-lapse imaging (Incucyte ZOOM) We used this analysis to examine the effect that topographical cues impart to the shape of ASCs. We examined the cell shape metrics of cell area, circularity, major axis and minor axis. Cell shape remained most similar between aligned and flat topographies with similar (F-test, P > 0.05) area, circularity, major axis and minor axis for the first 1.5, 504, 1.25 and 0.5 hours respectively. This indicates that the effect of biochemical stimulus dominates those of topography when influencing cell shape
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