Substratum effects of micro- and nano-structures on cellular behavior

Abstract

Substratum effects of micro- and nano-scaled structures on mammalian cell lines have experienced rapid developments during past decades. Tremendous studies have shown that micro- and nano- scaled surface morphology has great influences on cellular behavior and has great potential application in medical device design and organs regeneration. Although a variety of cell types have been used in cell-substrate studies for different purposes, information about how the cellular response of hepatic cells to the nanoporous and microgrooved structures is still insufficient The effects of groove/ridge width of the microgrooved structures on the mammalian cell culturing is usually overlooked. In this thesis, the cellular response of hepatic cells to the nanoporous and microgrooved is studied, including the cell spreading, cell elongation, cell alignment, and cell motility. Also, the effects of groove/ridge width are addressed on three mammalian cell lines (BEL-7402, MIHA, and HeLa). Three experiments were performed. Firstly, the effect of nanoporous surface on hepatic cell line, BEL-7402, was studied. The nanoporous surface (140 nm) was fabricated by anodize alumina membrane and microcontact printing techniques on PDMS surface. Cellular behaviors were analyzed with scanning electron microscope and time-lapse imaging. The results showed that cell projected area was reduced with cell migration speed was promoted on porous surface when compared with flat control surface. Secondly, the effect of microgrooves surface (10 μm, 30 μm and 50μm, with equal ridge and groove width) on hepatic cell line, BEL-7402, was studied. The microgrooved surface was fabricated by microcontact printing on PDMS. Cellular behaviors were analyzed with scanning electron microscope and time-lapse imaging. The results showed that cell elongation, alignment and directional migration was promoted by the groove structure when comparing with flat surface. Thirdly, the effect of microgrooved PDMS surfaces with varied ridge width and groove width on three mammalian cell lines (BEL-7402, MIHA, and HeLa)was studied. Microgrooved PDMS surfaces with nine combination of ridge width (5 μm, 10 μm and 30 μm) and groove width (5 μm, 10 μm and 30 μm) were fabricated using photolithography and soft lithography. The results showed that all grooved structures have almost same affection on the cellular response, independent of the cell type. Also, our result showed that the cell elongation displayed same pattern on all micrgrooved surfaces, independent of the groove/ridge width changes. In addition, our result showed that microgrooved surface that contained 10 μm ridge or groove were less effective in aligning cells. On the other hand, microgrooved surface 5×5, 5×30, 30×5 and 30×30 showed most effective in aligning cell when compare with other grooved surface and flat control surface. Our result provide information on how cell response to surface morphology at nano-scale and micro-scale. These informations are highly conducive for the liver regeneration, cancer metastasis study, and other tissue engineering research.