Papers by Keyword: Cell Spreading

Abstract: Force-directed placement method for large scale integration physical design is a very effective and fast method to spread the cell uniformly in the placement region. But this kind of method also create large amount of cell overlap in initial placement. In this paper, we present an effective method to cope with cell spreading and add additional force without damaging the wire length. It mainly takes the following method: Firstly, in the prior period of iteration n we keep limit the cell moving distance using a rectangle structure .Because the prior iteration play a decisive role in the final placement quality. Secondly, after the cell relative order determined we can use a new method to compute the weight of additional force to accelerate converge. Thirdly, a strategy called iterative local refinement is added in the well-distributed placement to further reduce the total wire length.

Abstract: The osteoblast adhesion to the substrates are recognized to play a fundamental role in osteoconduction process. The purpose of this study was to evaluate the in vitro behavior of osteoblasts cultured on polarized hydroxyapatite (HA), having the enhanced osteobonding abilities. Osteoblast-like cells were seeded onto the polarized HA and investigated the adhesion and motility. The polarization had no effects on the percentage of the number of the spreaded cells against all the adhered cells, but had significant effects on the elongation of adhered cells from fluorescent observation and on the cell motility showed by the wound healing assay. The charges induced on the HA surface accelerated the cytoskeleton reorganization of the adhered cells cultured on HA specimens. The acceleration was emerged as the cells shape, actin filament pattern such as stress fiber formation, and the prolongation of the cell movement distances.

Abstract: The response of osteoblast-like cells cultured on blasted and/or acid etching surfaces and the influence of surface texture or microtopography on cell attachment, cell proliferation, and the gene expression of the osteoblastic phenotype using ROS 17/2.8 cell lines were evaluated. The blasted and/or acid etching surfaces were significantly rougher in comparison to machined and etched surfaces (p < 0.05). On X-ray diffraction analysis, titanium hydride (TiH2) was observed on the surface etched with a mixture of HCl-H2SO4 solution, whereas TiH2 was not observed on machined and blasted surfaces. After 24 h incubation, most of the cells of all the groups had a flattened, polygonal shape and were fully spread, exhibiting the onset of proliferation. The MTT assay showed a significant decrease on the blasted surface compared to the machined surface at 7 day culture (p < 0.05). The expression of osteopontin mRNA, α1 (I) collagen mRNA, and alkaline phosphatase mRNA on rough surfaces was higher than on the machined surfaces, and was highest on the blasted surface at day 7.

Abstract: A new technique for micropatterning surfaces for cell growth support is described and characterized. This technique allows covering of large three-dimensional surfaces at low cost with controllable micropatterns. This method takes advantage of the random properties of aerosols and the principles of liquid atomization. Parameters of interest were the pressure of atomization air, the flow rate and volume of the atomised liquid, and the distance between the spray nozzle and the surface of the sample. The experimental setup permitted to obtain mean diameters of spots between 10 and 20 microns with a maximum surface coverage of 20%. In an initial step, polytetrafluoroethylene (PTFE) films were treated with ammonia plasma to insert amino groups on the surface. The ammonia plasma treated films were immersed in a solution containing sulfosuccinimidyl 4-(N-maleidomethyl)cyclohexane-1-carboxy-late (SSMCC) to permit the introduction of maleimido groups on the PTFE surface to subsequently conjugate peptides through a sulfhydryl containing N-terminal cystein residue. Plasma/S-SMCC pretreated surfaces were then sprayed with peptide sequences CGRGDS and CWQPPRARI. Our data showed that spots of CGRGDS peptides over a background of CWQPPRARI peptides were the most effective combination to enhance endothelialization.