TY  - GEN
A1  - Schulz, Simon Daniel
N2  - Microstructured interfaces such as micropillars made of polydimethyl-siloxane (PDMS) provide a novel approach both as topologically defined, force sensing substrates in cell culture as well as scaffolds for biomimetic protein assays. This work is divided into two parts. In the first part, PDMS micropillar arrays functionalized with fibronectin, are applied as a biomechanical microenvironment for immortalized human gingival keratinocytes (IHGKs) and gingival connective-tissue fibroblasts (GCTFs). IHGKs and GCTFs show successful adhesion and growth on the pillar heads and exert forces up to about 110 nN in the case of IHGKs and about 174 nN for GCTFs. Varying the interpillar distances affects the early keratinocyte differentiation and morphology. At decreasing inter-pillar distances the IHGKs show an increased keratin 1 (K1) extension in the cytoplasm, increased mRNA transcription of keratin 1 and a shape change from a more linear to a more round form. A novel GCTF-IHGK co-culture system is developed as a model of the epithelial tissue, to study explicitly the role of the GCTFs in the morphogenesis of the derived epithelial equivalents. The epithelial equivalents, cultured for 7 and 14 days on GCTF-populated pillar arrays, are found more similar to the in vivo phenotype than the GCTF-free cultures. These findings are confirmed by following the mRNA transcription levels for keratin 1. A novel, transparent microfluidic platform, based on PDMS pillars is developed in the second part of this work. It is designed to investigate actin cortex models and to provide control over the physicochemical environment, allowing simultaneous high resolution fluorescence microscopy. The formation of crosslinking networks is observed using various crosslinkers, such as filamin, myosin II, alpha-actinin and magnesium ions. Dependent of the geometric configuration of the actin filaments anchored to the pillar tops, so-called zipping crosslinks are observed. The zipping velocity is both influenced by the flow speed, as well as the number and the configuration of the filaments involved in the process. It is found to range between 2 - 15 µm/s. To further quantify the crosslinking process, the flow-cell is combined with an optical tweezers system. The unzipping forces are measured for the crosslinkers alpha-actinin and magnesium ions. Forces of about 17 - 20 pN are derived for magnesium ions and about 30-45 pN for alpha-actinin.
AV  - public
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/9485/
TI  - Application of Micropillar Interfaces: A Study on Human Periodontal Cells and Actin Biomimetic Systems
Y1  - 2009///
KW  - Biofunktionalisierung
KW  -  Mikrosäule
KW  -  Epithel
KW  -  MikrofluidikBiofunctionalization
KW  -  Force Sensor
KW  -  Biomechanics
KW  -  Actin Networks
KW  -  Micropillar
ID  - heidok9485
ER  -