610 Medizin, Gesundheit
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Programmable nano-bio interfaces driven by tuneable vertically configured nanostructures have recently emerged as a powerful tool for cellular manipulations and interrogations. Such interfaces have strong potential for ground-breaking advances, particularly in cellular nanobiotechnology and mechanobiology. However, the opaque nature of many nanostructured surfaces makes non-destructive, live-cell characterization of cellular behavior on vertically aligned nanostructures challenging to observe. Here, a new nanofabrication route is proposed that enables harvesting of vertically aligned silicon (Si) nanowires and their subsequent transfer onto an optically transparent substrate, with high efficiency and without artefacts. We demonstrate the potential of this route for efficient live-cell phase contrast imaging and subsequent characterization of cells growing on vertically aligned Si nanowires. This approach provides the first opportunity to understand dynamic cellular responses to a cell-nanowire interface, and thus has the potential to inform the design of future nanoscale cellular manipulation technologies.
Tumorzellen on the move : mikrosystem-basierter Assay zur Untersuchung der Tumorzellen-Migration
(2016)
Die Invasion von Tumorzellen in umliegendes Gewebe und die Bildung von Metastasen transformieren einen lokal wachsenden Tumor in eine systemische und lebensbedrohliche Krankheit mit schlechter Prognose. Dabei spielt die aktive Migration der Tumorzellen eine entscheidende Rolle. Tumorzellen gelangen durch die aktive Zellbewegung in das Lymph- oder Blutsystem und breiten sich im Körper aus. Bei der Invasion in ein neues Organ migrieren die Zellen ebenfalls wieder in komplexer Weise durch das Gewebe und können schließlich dort Metastasen bilden. Auf Grund der enormen medizinischen Relevanz der Tumorzell-Invasion, wird die Bewegung von Tumorzellen seit Jahrzehnten unter Laborbedingungen umfassend untersucht und ist ein wichtiger Marker für die Aggressivität der Tumorzellen. Zur Bewegungsanalyse gibt es mehrere experimentelle und auch kommerziell erhältliche in-vitro Untersuchungsmethoden. Ziel des interdisziplinären Projektes „MigChip“ ist die Entwicklung, Herstellung und experimentelle Validierung eines Mikrofludik-Chips zur verbesserten, detailgenauen in-vitro Untersuchung der Tumorzellen-Migration.
The physiology of vascular cells depends on stimulating mechanical forces caused by pulsatile flow. Thus, mechano-transduction processes and responses of primary human endothelial cells (ECs) and smooth muscle cells (SMCs) have been studied to reveal cell-type specific differences which may contribute to vascular tissue integrity. Here, we investigate the dynamic reorientation response of ECs and SMCs cultured on elastic membranes over a range of stretch frequencies from 0.01 to 1 Hz. ECs and SMCs show different cell shape adaptation responses (reorientation) dependent on the frequency. ECs reveal a specific threshold frequency (0.01 Hz) below which no responses is detectable while the threshold frequency for SMCs could not be determined and is speculated to be above 1 Hz. Interestingly, the reorganization of the actin cytoskeleton and focal adhesions system, as well as changes in the focal adhesion area, can be observed for both cell types and is dependent on the frequency. RhoA and Rac1 activities are increased for ECs but not for SMCs upon application of a uniaxial cyclic tensile strain. Analysis of membrane protrusions revealed that the spatial protrusion activity of ECs and SMCs is independent of the application of a uniaxial cyclic tensile strain of 1 Hz while the total number of protrusions is increased for ECs only. Our study indicates differences in the reorientation response and the reaction times of the two cell types in dependence of the stretching frequency, with matching data for actin cytoskeleton, focal adhesion realignment, RhoA/Rac1 activities, and membrane protrusion activity. These are promising results which may allow cell-type specific activation of vascular cells by frequency selective mechanical stretching. This specific activation of different vascular cell types might be helpful in improving strategies in regenerative medicine.
In vivo, cells encounter different physical and chemical signals in the extracellular matrix (ECM) which regulate their behavior. Examples of these signals are micro- and nanometer-sized features, the rigidity, and the chemical composition of the ECM. The study of cell responses to such cues is important to understand complex cell functions, some diseases, and is basis for the development of new biomaterials for applications in medical implants or regenerative medicine. Therefore, the development of new methods for surface modifications with controlled physical and chemical features is crucial. In this work, we report a new combination of micelle nanolithography (BCML) and soft micro-lithography, for the production of polyethylene glycol (PEG) hydrogels, with a micro-grooved surface and decoration with hexagonally precisely arranged gold nanoparticles (AU NPs). The Au-NPs are used for binding adhesive ligands in a well-defined density. First tests were performed by culturing human fibroblasts on the gels. Adhesion and alignment of the cells along the parallel grooves of the surface were investigated. The substrates could provide a new platform for studying cell contact guidance by micro structures, and may enable a more precise control of cell behavior by nanometrically controlled surface functionalization.