Einfluss einer Nanosäulentopographie und deren Variation in geometrischen Parametern auf zellbiologische Funktionen humaner mesenchymaler Stromazellen

Abstract

Cells embedded in extracellular matrix are surrounded by various topographical dimensions, whereby nanostructured topographies play a pivotal role in influencing cellular behaviour. Consequently, an exposition of nano topographies on biomaterials could optimize tissue integration.

The presented thesis should analyse the effect of nano-scaled changes of geometries by using highly defined, hexagonally ordered 3D nanopillars on the cell behaviour of human mesenchymal stem cells (MSC). The nanostructured SiO2-surfaces with defined pillar diameter (30 nm, 10 nm), height (20 nm, 50 nm) and pillar-to-pillar distance (50 nm, 100 nm) were produced lithographically by the Institute for Solid State Physics, University of Ulm. A whole-genome microarray analysis from topographies with a pillar height of 20 nm and 50 nm revealed mainly a significant downregulation of several cell cycle regulating genes in MSC on the 50 nm height when compared to the control surfaces. Also, DKK1 and TNFAIP3, both involved in regulating differentiation processes, were affected. In contrast, only few significant changes in cellular responses were detectable on the 20 nm pillar height. However, when analysing the expression of selected cell cycle genes with higher case numbers in confirmatory qPCR-analysis, cells showed on both pillar heights significant downregulations. Variations in gene expression could also be observed on specific topographies with reduced diameter and partly in addition with downsized pillar distance. Furthermore, the results showed specific cell responses depending on the topography. Besides downregulation of DKK1, a significantly reduced secretion of Dkk1 could be shown on both pillar heights. On 50 nm height additionally a downregulation of TNFAIP3 was observed, suggesting a possible osteogenic capacity of this topography. Furthermore, consistent with downregulated cell cycle genes, a reduced proliferation of MSC was measured depending on the topography. Also, cell-spreading and vinculin synthesis were found to be influenced by the nanopillars. Finally, a pillar-induced modulation of cell migration was measurable in live cell imaging experiments.

In conclusion, this work showed that specific nanopillar topographies led to different cell responses in terms of gene expression, proliferation, cell morphology, and migration.