Electroporation of cells is a widely-used tool to transport molecules such as proteins or nucleic acids into cells or to extract cellular material. However, bulk methods for electroporation do not offer the possibility to selectively porate subpopulations or single cells in heterogeneous cell samples. To achieve this, either presorting or complex single-cell technologies are required currently.
View Article and Find Full Text PDFContinuous flow cell sorting based on image analysis is a powerful concept that exploits spatially-resolved features in cells, such as subcellular protein localisation or cell and organelle morphology, to isolate highly specialised cell types that were previously inaccessible to biomedical research, biotechnology, and medicine. Recently, sorting protocols have been proposed that achieve impressive throughput by combining ultra-high flow rates with sophisticated imaging and data processing protocols. However, moderate image quality and high complex experimental setups still prevent the full potential of image-activated cell sorting from being a general-purpose tool.
View Article and Find Full Text PDFWe present a method for label-free imaging and sorting of cancer cells in blood, which is based on a dielectrophoretic microfluidic chip and label-free interferometric phase microscopy. The chip used for imaging has been embedded with dielectrophoretic electrodes, and therefore it can be used to sort the cells based on the decisions obtained during the cell flow by the label-free quantitative imaging method. Hence, we obtained a real-time, automatic, label-free imaging flow cytometry with the ability to sort the cells during flow.
View Article and Find Full Text PDFWith the advent of single-cell technologies comes the necessity for efficient protocols to process single cells. We combine dielectrophoresis with open source computer vision programming to automatically control the trajectories of single cells inside a microfluidic device. Using real-time image analysis, individual cells are automatically selected, isolated and spatially arranged.
View Article and Find Full Text PDFIn vitro cultured neuronal networks with defined connectivity are required to improve neuronal cell culture models. However, most protocols for their formation do not provide sufficient control of the direction and timing of neurite outgrowth with simultaneous access for analytical tools such as immunocytochemistry or patch-clamp recordings. Here, we present a proof-of-concept for the dynamic (i.
View Article and Find Full Text PDFA major challenge in the field of optical imaging of live cells is achieving rapid, 3D, and noninvasive imaging of isolated cells without labeling. If successful, many clinical procedures involving analysis and sorting of cells drawn from body fluids, including blood, can be significantly improved. A new label-free tomographic interferometry approach is presented.
View Article and Find Full Text PDFUnderstanding the dynamics of signal transduction processes that are induced by cell-cell or cell-surface interactions requires the physical stimulation of the cells of interest on a single-cell level and without any ill-defined contacting of their cell membrane. However, standard cell culture techniques are inapplicable for this task as they do not provide cell and particle handling at sufficiently high spatial and temporal resolution and are limited to ensemble measurements. Here, we present a novel process line for the individual stimulation of single cells with bioactive surfaces, like other cells or particles, and the simultaneous analysis of the induced cytosolic calcium signals.
View Article and Find Full Text PDFWound repair is a quiescent mechanism to restore barriers in multicellular organisms upon injury. In chronic wounds, however, this program prematurely stalls. It is known that patterns of extracellular signals within the wound fluid are crucial to healing.
View Article and Find Full Text PDFBefore undergoing a reconstructive procedures of the nose most patients ask how they will look postoperatively. Anthropometric measurements of the nose described by Farkas represent standard values. A comparison of pre- and postoperative anthropometric measurements may help to double-check the correctness of intraoperative "eye-balling" measurements with regards to postoperative appearance.
View Article and Find Full Text PDFThe prospect of novel therapeutic approaches has renewed the current interest in the fusion of rare cells, like stem cells or primary immune cells. While conventional techniques are only capable of mass fusion, lab-on-a-chip systems often still lack an acceptable method for making the cells available after processing. Here, we present a microfluidic approach for electrofusion on the single-cell level that offers high control over the cells both before and after fusion.
View Article and Find Full Text PDFIntroduction: The purpose of this study was to investigate the adhesion and invasion of periodontopathogenic bacteria in varied mixed infections and the release of interleukins from an epithelial cell line (KB cells).
Methods: KB cells were co-cultured with Porphyromonas gingivalis ATCC 33277 and M5-1-2, Tannerella forsythia ATCC 43037, Treponema denticola ATCC 35405 and Fusobacterium nucleatum ATCC 25586 in single and mixed infections. The numbers of adherent and internalized bacteria were determined up to 18 h after bacterial exposure.
In order to elucidate the dynamics of cellular processes that are induced in context with intercellular communication, defined events along the signal transduction cascade and subsequent activation steps have to be analyzed on the level of individual cells and correlated with each other. Here we present an approach that allows the initiation of cell-cell or cell-particle interactions and the analysis of cellular reactions within various regimes while the identity of each individual cell is preserved. It utilizes dielectrophoresis (DEP) and microfluidics in a lab-on-chip system.
View Article and Find Full Text PDFThe quantity of therapeutic gene products released from genetically engineered cells can be controlled externally at different levels. The widely used approach of controlling expression, however, generally has the disadvantage that chemical substances must be applied for stimulation. An alternative strategy aims at controlling gene products at posttranslational levels such as secretion.
View Article and Find Full Text PDFThe gentle and careful in vitro processing of live cells is essential in order to make them available to future therapeutic applications. We present a protocol for the activation of single-T cells based on the contact formation with individual anti-CD3/anti-CD28 presenting microbeads in a lab-on-chip environment. The chips consist of microfluidic channels and microelectrodes for performing dielectrophoretic manipulation employing a.
View Article and Find Full Text PDFImplicit Association Tests (IATs) are supposed to measure associations between concepts. In order to achieve that aim, participants are required to assign individual stimuli to those concepts under time pressure in two different tasks. Previous research has shown that not only the associations of the concepts with each other, but also the stimuli's cross-category associations influence the observed reaction time difference between these tasks (i.
View Article and Find Full Text PDFWe present a simple lab-on-chip device for handling small samples of delicate cells, e.g. stem cells.
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